US3432321A - Methods for improvement of asphalts and oil emulsions useful therein - Google Patents

Description

March 1l, 1969 F. s. ROSTLER 3,432,321

METHODS FOR IMPROVEMENT 0F AsPHALTs AND OIL EMULsIoNs USEFUL THEREIN Original Filed April 19, 1963 Sheet of 5 GROUP 1 GRQUP O (com gw a1-lad) ssc-l Nousvzlv @avais/w' O/o WQ/TZ .5. Ros-n.512 INVENTOR.

ATTRN EY.

March 11, 1969 F. s. ROSTLER 3,432,32 l METHODS FOR IMPROVEMENT OF AsPHALTs AND OIL EMULSIONS USEFUL THEREIN Original Filed April 19, 1963 A? of5 Sheet HQDONFU H n nodnu ND RDON .RQ/.T2 .5. 22057152 INVENTOR.

ATTO R EY March 11, 1969 F. s. RosTLER 3,432,321

METHODS FOR IMPROVEMENT OF ASPHALTS AND OIL EMULSIONS USEFUL THEREIN original Filed April 19. 196s sheet 3 of s SAMPLES l-l7 LOSS AFTER SOO HES. WEATHERING GMS LOSS/[OOO GMS SHOT ABEASION (OLLVZI) fm N FQ/TZ S HOST/ EQ NVENTOR.

March ll, 1969 F. s. ROSTLER METHODS FOR IMPROVEMENT OF ASPHALTS AND OIL EMULSIONS USEFUL THEREIN Original Filed April 19, 1963 Sheet 04m, b. Q. mA

.w m V N 0h D@ Om OV om O- ov om om 0h om om oo.

INVENTOR. Jriz/TZ 5. 72057152 BY i/n ATTORN EY March 11, 1969 F. s. RosTLl-:R 3,432,321

METHODS FOR IMPROVEMENT OF ASPHALTS AND OIL n EMULSIONS USEFUL THEREIN Orlglnal Flled April 19, 1963 Sheet 5 of 5 cn Y D 1 o J C Q0 .20o soo CURVE DEFORMATION INCHES x10-3 A 4B PEN. ASPHALT WEATl-IEIZED I4 DAYS B 48 PEN. ASPHALT UNWSATHERSD 27E/TZ S RIOIVETR c 48 PEN. ASPHALT ral-:Acres: wrrH MALTENES SMuLsloN AND wem-Henao I4 DANS D 20o-Boo PEN. ASPHALT uNwSA'r-HSQED l E 4B PEN. ASDHALT TRSATSD WITH MALTENSS BY IN KenoSaNE. AND WSATHSQSD 14 DAVS ATTORN EY.

United States Patent O Claims ABSTRACT OF THE DISCLOSURE A cationic aqueous emulsion of petroleum oil, which oil is substantially free of asphaltenes, and contains nitrogen bases, irst acidatiins, second acidafins, and paraflins, with N, A1, A2 and P denoting respectively the percent by weight of the nitrogen bases, tirst acidatiins, second acidaiiins and paraiiins in the petroleum oil. The quantities of the components of the petroleum oil, expressed in the ratio N -l-Al/P-l-Az give a value in the range from about 0.01 to about 19.0 and the petroleum oil has an initial boiling point at 10 millimeters of mercury absolute of about 160 C. and is substantially free of fractions boiling below about 200 C. at that pressure. The aqueous emulsion is a balance emulsion and contains a cationic emulsifier in the range of about 0.5% to about 1.5% by weight of the oil in the emulsion and also contains a nonionic emulsitier in the range of 0.5% to 2.0% by Weight of the oil in the emulsion. The emulsion is particularly suited for the treatment of weathered asphalt to improve its properties.

This invention relates to methods for improving the durability of asphalts, both weathered and unweathered, by adjusting the components of the asphalt other than the asphaltenes content, to provide a favorable balance of the concentrations of these several components other than asphaltenes, and to improve the bonding power of the asphalt and the abrasion resistance of asphaltic compositions formed of asphalt and mineral aggregates, for example, sand and rock.

This invention is a result of extensive and continuing research into the chemical constitution of asphalts and into the chemistry of the weathering process of asphaltic pavements and other asphaltic compositions.

This application is a division of application Ser. No. 274,193, filed Apr. 19, 1963, now Patent 3,162,101, which is a continuation-in-part of application Ser. No. 497,397, tiled Mar. 28, 1955, Ser. No. 45,023, led July 25, 1960 and Ser. No. 254,399, iiled Ian. 28, 1963.

Asphalts are generally understood to comprise nondistillable and high-boiling residues of petroleum fractions, consisting of asphaltenes, that is, components which are insoluble in n-pentane and of maltenes, i.e., fractions soluble in n-pentane.

Asphalts also include natural asphalts found as such, as deposits in the earth or produced from petroleum crude oils by distillation, or from cracked petroleum fractions. Asphalts are also produced by blending such residues with liquid petroleum oil fractions and also by blending such 'ice petroleum oil fractions with residues precipitated from the above asphalts by solvents, such as liquid propane.

Asphalts come in various grades, classiiied according to their penetration values, as is well known in the asphalt art. Paving grade asphalts are understood to include those asphalts usually produced by reduction of petroleum fractions, by steam distillation or vacuum distillation, or blending oils with natural, precipitated or reduced asphalts from petroleum oils, which have a penetration value of 32 or more, for example, 200-300 (5, 100 gm.) [Test T49-49, American Association of State Highway Oiiicialsl.

Other grades include rooting asphalts and other well recognized grades of asphalts derived from petroleum or from similar natural deposits.

The pentane soluble components, i.e., maltenes, have been identified and named as follows: The nitrogen bases, symbolized by the letter N; the Group I unsaturates, called iirst acidatiins, identified by the symbol A1; the Group II unsaturates, also known as second acidafins, identified by the symbol A2, and the saturated fraction, also known as the paraiiins fraction, identified by the letter P. The asphaltenes are identified by the letter A.

The method of analysis by which each one of these groups may be determined is described in Compounding Rubber with Petroleum Products, by Rostler and Sternberg, published -in Industrial and Engineering Chemistry, vol. 4l, at pages 598-608, of March 1949. The method has been further described in Composition and Changes in Composition of Highway Asphalts, -100 Penetration Grade, published in proceedings of Association of Asphalt Paving Technologists, vol. 3 l, January 1962, at pages 7279. This method of analysis and the terminology have been adopted in Governmental specifications of high boiling oils, as recorded in the report of the work done in the Government laboratories in the University of Akron, Ohio, in the article entitled, Oil Types in the Program for Oil Extended Rubbers, by Taft, et al., Industrial and Engineering Chemistry, 1955, vol. 47, pages 1077-1090. The method has further been adopted as an A.S.T.M. Procedure under the designation D-2006-62T.

The discussion of the method is also described in the article entitled, Iniiuence of Chemical Composition of Asphalts on Performance and Particularly Durability, by Rostler and White, in the American Society for Testing Materials Special Publication No. 277, at pages 64-88.

This method identities the components of asphalts and petroleum fractions having an initial boiling point not lower than C. at l0 mm. Hg. absolute pressure, previously described: asphaltenes, nitrogen bases, rst acidaiiins, second acidafiins and paraflins.

Throughout this application, whatever the terms asphaltenes, nitrogen bases, tirst and second acidaiiins, also identified as Group I or Group II unsaturates, and paratiins are used, it will be understood that they refer to the fractions as determined by the above analytical procedure.

In application Ser. No. 497,397, I grouped the nitrogen bases and the Group I and Group II unsaturates in the term resinous components of the asphalt.

Application Ser. No. 497,397 reports the discovery that the weathering produces an increase in the asphaltenes content, and that the total percentage of the resinous components decreases. The change appears explainable by the fact that the Group I unsaturates and nitrogen bases change into asphaltenes with a reduction in the bonding power of the asphalt. The result of weathering is to cause an unbalance as between the saturated fractions, on the one hand, and the resinous components, on the other hand. The application also describes the discovery that weathered asphalts may be rejuvenated by establishing the proper balance between the resinous components and the paraffins in the rejuvenated asphalt.

The process of the above application rejuvenated the weathered asphalt by reestablishing the balance of components, as it existed in the original asphalt before weathering. This is accomplished by adding fractions of maltenes which modify the composition of the weathered asphalt by the addition of sufficient resinous material to raise the content of the resinous component of the weathered asphalt so that the balance of components found in the original asphalt may be reestablished. The maltenes added contain the resinous components, that is, the nitrogen bases, and first and second acidaf'lins, in amounts of at least 50% by weight of the maltenes. The added maltenes may also contain saturated components, i.e., the paraffins.

The maltenes are preferably added to the weathered asphalt in emulsion form. The amount of maltenes added to the weathered asphalt is sufficient to materially improve the properties of the asphalt which, by weathering, has had its usefulness markedly reduced, as evidenced by the low penetration value and brittleness of the weathered asphalt. The maltenes added to the weathered asphaltic pavement may be in amounts to lbring the asphalt content of the pavement up to 1.3 to 1.4 times the amount specified for that pavement, for example, about 4% to 8% by weight of the asphaltic aggregate composition constituting the pavement.

The aforesaid application is herewith incorporated by this reference.

Subsequent to the filing of the above application, my continued research into the subject developed further discoveries, including the effect of the composition on the durability of asphalts, as indicated by the abrasion resistance, using test procedures adopted by the Materials and Research Department of the California Division of Highways, as described by F. N. Hveem in the Proceedings of the Association of Asphalt Paving Technologists, Technical Section, Dec. l, 1943, vol. 15, page 111, et seq.; and by John B. Skog, A.S.T.M. Special Technical Publication 212, page l, et seq. The test consists of mixing two parts of asphalt with 100 parts of Ottawa sand at various temperatures and determining the abrasion loss by impinging a stream of steel shot against a compacted specimen. Additional samples are made in the same manner and exposed in a weathering machine to infrared heat for various times, and weathered samples withdrawn at various intervals and likewise tested. The parameter reported is grams loss per 1,000 gram shot. This test is herein referred to as the shot abrasion test.

Experience with this test has shown that the higher the abrasion loss by this test, after weathering, the inferior is the life expectancy of the road produced from these asphalts. (See the Skog article, page 8.) It is thus a measure of the durability of the asphalt, i.e., its resistance to loss of Ibonding properties and other characteristics which are useful in pavements.

Discoveries made in connection with this continued research are disclosed in my application, Ser. No. 45,023. Data are reported as a result of this continued investigation by the applicant upon 200 to 300 penetration grade asphalt produced from California crude oils derived from the Los Angeles basin, Valley and Santa Maria fields in California. Thirteen such asphalts are reported in the aforesaid application. Additional data are reported for asphalts produced from California crude oils and from blends produced from gilsonite and various oil fractions. The asphalt blends had peneration values in the range of 200-300, and the gilsonite asphalts had penetrations ranging from 85 to 25,7, y

These asphalts were subjected to the above tests, and the data showed that the abrasion resistance measured by the shot abrasion test increases with an increase in the paraftns content (P) of the asphalt in a regular manner. The results of these experiments showed that, in order to obtain an asphalt of penetration from about 30 to about 300, having a loss of under 3 grams in the above shot abrasion test after 500 hours weathering, the percent parafns in the asphalt should be above about 15%, and up to about 50% g and the higher the percentage in this range, the more abrasion resistant the asphalt.

The effects of weathering have been Shown in application Ser. No. 45,023 to result from an unbalance in the asphaltenes and saturated fractions on the one hand, and the unsaturated and nitrogen bases components on the other. The effect of unbalance is the lesser, the greater the percentage of saturated fractions in the asphalt originally employed.

The application Ser. No. 45,023 taught that asphalts may be rejuvenated by adding the parains fractions to obtain the required balance to produce an asphalt of desirable properties. The percent of resinous fractions has, however, to be high enough to prevent syneresis. It is to be observed that maltenes employed may also contain the unsaturated fractions and may also contain nitrogen bases.

With some weathered asphalts, which are relatively uncommon, which are unusually high in peptizing fractions, to wit, the nitrogen bases and other resinous fractions, to wit: first and second acidans, the maltenes may be substantially all parafns, i.e., higher than and even In the cases which are normally encountered, I found that a weathered asphalt which has deteriorated may be suitable for the purpose of the structure in which it is used, if the weathered asphalt is replasticized by adding thereto the selected fractions of maltenes, containing a suitable concentration of the components in which the asphalt is deficient. Such fractions may be produced from petroleum oils by removing asphaltenes and wax of the oil, if the oil is a waxy oil, to produce fractions containing about 20% to 85% saturated components, the remainder being reactive components, to wit: nitrogen bases and first and second acidaffins.

The application, Ser. No. 45,023, further discloses data which show that the durability of rejuvenated asphalt is the greater the greater the percent paraflins (P), and that by increasing the parains content of the original asphalt employed in the road construction, the durability, as measured by the shot abrasion test, at various stagesl of weathering was above that of the original asphalt, the abrasion loss being markedly reduced.

The results of the discoveries as reported in application Ser. No. 45,023, therefore, showed that the addition of maltenes containing sufficient paraffins fractions (P), in amount suicient to raise the parafns content of a weathered asphalt, could produce an asphalt of bonding power and durability even better than that of the unweathered, original asphalt.

As disclosed in the said application, Ser. No. 45,023, the fractions of maltenes are used in emulsion form, preferably as a cationic emulsion, and preferably also as a balanced emulsion containing both cationic and nonionic emulsifiers.

The aforesaid application, Ser. No. 45,023, is herewith incorporated by this reference.

Continued research and investigation in this field resulted from the opportunity afforded applicant to investigate 119 asphalts obtained from crude oils produced in various states of the United States and in Venezuela, in Canada and in Mexico, and produced by various methods, including steam distillation, air blowing, blending, propane fractionation, and fluxing with heavy oils. The details of the test data upon these various asphalts and 'their origins are given in Public Roads of August 1959, vol. 30, No. 9, issued by the Department of Commerce, United States Government, pages 197-207, and also in the Proceedings of the Association of Asphalt Paving technologists, vol. 28, January 1959, pp. 242-279.

Samples of these asphalts were secured, and the samples were analyzed according to the analytical procedures tion ratio from about .3 to above 2, and have abrasion losses by the above pellet tests ranging from no loss, or zero loss, to about 100%. These asphalts may be classied into various groups, according to their loss on abrasion by the above pellet tests, taken as the average of the 5 glven 1n the above method by Rostler and Sternberg and abrasion loss before and after aglng, as shown 1n Table I.

TABLE I Durability N -I-Ai/P-l-Azl Average Average Group Percent Abrasion 2 Durability Rating Range Average Parans 1 0 0.4 0.28 39.8 50 Decreasing durability with decreasing parameter value.

0. 82 13. 8 5. 7 Superior.

l. 09 11. 5 8. 9 Good.

1. 34 9. 9 29. 6 Satisfactory.

1. 58 8. 9 45. 4 Fair.

1. 84 9. 0 52. 7 Inferior.

1 Composition of original (nonaged) asphalt. 2 Average o percent abrasion (Pellet Method) before and after 7 days aging.

by a weathering and abrasion test method reported in the article entitled Influence of Chemical Composition of Asphalts on Performance, Particularly Durability, by Rostler and White, published in American Society for Testing Materials, Special Technical Publication No. 277, pages 64-88, 1959. The abrasion test method, which, as shown in the article (see infra) Composition and Changes in Composition of Highway Asphalts, 85-100 Penetration Grade, correlates with the shot test, will herein be referred to as the pellet test.

This investigation confirmed the results reported in application Ser. No. 45,023, and showed that as a general rule, the asphalts show greater abrasion resistance and durability to weathering, the higher the parafnc content, provided the parains content is not so high as to destroy the suitability of the asphalt as a bonding agent. It also explains and reconciles the results of the two previous applications, and shows that while in each case an improvement in the asphalt is obtained by following the procedures of the aforesaid applications, they are each a special case of a more general principle which makes it possible to improve the durability of asphalts, both weathered and unweathered.

The reason that this is so, as now appears from my further investigation, is that, as the parains content (P) of the asphalt increases, so is there an increase in the sum of the parains and second acidains (A2), and that the controlling factor is the ratio of the sum of the nitrogen bases and the rst acidains (N+/11) to the sum of the parains and the second acidains (P4-A2), expressed as the ratio of the percentages present in the asphalt. It thus appears that the reason that the asphalts of higher parafns 'content show a greater abrasion resistance and increased durability is that this ratio decreases as the concentration of parat-line increases. However, the parafins content is not as sensitive as indicator for durability of many asphalts with parains contents in excess of about to 15%. The above maltenes composition ratio N-l-Al/P-l-AZ, is thus a better and more sensitive index of the durability of the asphalt than the content of the component P.

Asphalts investigated by means of the pellet test, including the 119 asphalts and two other asphalts of 85 to 100 penetration grade (Samples No. 19 and 20 of Table III) which were blended to have an excessively low ratio, showed that the asphalts vary in their maltenes composi- FIGURES 1-5 are plots of data given in this specication.

FIGURE l shows the average abrasion loss by the -pellet test plotted against the composition ratio of the original unaged asphalt. The average abrasion loss is calculated as the average of the. abrasion loss of the unaged mixture of Ottawa sand and asphalt, and the sarne mix, after aging seven days as described in the above article by Rostler and White in the article in vol. 31 of the Proceedings of the Association of Asphalt Technologists, supra and A.S.T.M. Special Technical Publication No. 277.

The solid curve is drawn as a `best t to the ydata obtained from the above -100 penetration grade asphalts, and the dotted line gives the trend line for asphalts of composition ratios in the various groups.

The marked points where the ratio is .4 and less are for asphalts Sample Nos. 19 and 20, as above. All other points are the averages as given in Table I. The asphalts fall into six groups. Group O, with composition ratios less than 0.4, represents compositions which are of consistency of a cheesy and putty-like character rather than asphalts. At about 0.4 the compositions attain the desirable characteristic of paving grade asphalts.

The asphalts of Groups I to V may be rated as stated in the table, based on their durability. The lower the abrasion loss initially, and also the less abrasion loss after aging, the better is the asphalt, i.e., the lower the above average, the better the asphalt in its weathering characteristics. On top of FIGURE 1 is indicated the boundaries of the groups corresponding to values of the ratio for each group, plotted as abscissa.

Line D on FIGURE 4 and the same data plotted as a curve on FIGURE 2 plot the paraiins content of the groups of Table I against the same average abrasion loss.

The above tests show that, for the 85-100 penetration asphalts produced by various procedures from petroleum crude oils of various types and diverse geographic origins, the following conclusions may be drawn:

For asphalts with parafns content ranging from about 7% to about 40%, and asphaltenes content ranging from about 11% to 36%, the abrasion loss is a function of the ratio of N +A1/P-I-A2 as Well as of the parains content. It also appears that, for abrasion loss in excess of about TABLE II Initial Composition N -l-Ai/ .Abrasion Percent Percent P+A2 Loss1 parafiin .Asphaltenes 1 Determined by the shot abrasion test; on samples after weathering or 500 hours in the weathering machine.

The asphalts of Samples 1-13 were all 200-300 penetration grade asphalt. The table gives the percent parafns (P), the percent asphaltenes (A), and the ratio Samples 14-18 were all made by blending 32 penetration asphalt with various oil fractions to give a 200-300 penetration asphalt as follows:

Sample No.: Percent oil 14 (83% asphalt) 17 15 (73% asphalt) 27 16 (73% asphalt) 27 17 (45% asphalt) 55 18 (20% asphalt) 80 The 32 penetration asphalt had the following composition:

Percent Asphaltenes 13.4 Nitrogen bases 41.7 First acidaflins 13.9

Second acidans 19.3

Parains 11.7

N-I-A1/P-l-A2 1.82

The oil employed in Sample 14 was 50 S.A.E. heavy rafiinate which had the following composition:

Nitrogen bases 3.4 First acidafns 6.5

Second acidaflins 28.0

Paraflins 62.1

N-l-Al/P-i-Az .11

It had the following distillation range at mm. Hg pressure:

Sample was formed using S.R. stock, 154 Universal Saybolt seconds at 210 F.

8 The SR. stock had the following composition:

Nitrogen bases 14.6% First acidains 14.3% Second acidiflins 35.4% Paraftns 35.7% N-l-Al/P-l-Az 0.41

It had substantially the same distillation range as the S.A.E. 50 used in Sample =14.

The asphalt composition of the asphalt yin Sample 15 Sample 16 was made using 27% medium lubricating extract having the following composition:

Nitrogen bases 17.3% First acidains 17.3% Second acidafns 53.0% Parans 12.4% Nawal/1421Z .53

It had the following distillation range at 10 mm. Hg pressure:

C. Initial boiling point 205 50% point 263 End point 295 The blended asphalt in Sample -16 had the following composition:

Asphaltenes 8.4% Nitrogen bases 35.2% First acidaflins 19.5% Second acidains 25% 1.48 Parains 11.9%

Sample '17 was made using 55% heavy lubricating oil extract having the following composition:

Nitrogen bases `28.7% First acidans 21.2% Second acidaffins 41.3% Parains 8.8% N-l-Al/P-l-Az 0.99

It had substantially the same distillation range as the S.A.E. 50 used in Sample 14.

The blended asphalt in Sample 17 had the following composition:

Asphaltenes 4.0% Nitrogen Ibases V36.4% First acidaflins 18.7% Second acidans 30.5% Parafins 10.4% N+A1/P-l-A2 1.35

Sample 18 was made by blending with a concentrate of nitrogen bases having the following composition:

Nitrogen bases 84.6% First acidafhns 7.3% Second acidains 6.7% Parains 1.4% N-|-A1/P+A2 11 The blended asphalt had the following composition: Asphaltenes 1.5 Nitrogen bases 77% First acidaflins 7.8% Second acidans 9.1% Parains 4.6% N-f-Al/P-l-Az 6.12

The above distillation range and boiling points are determinad by A.S.T.M. Test 9341160.

FIGURE 4 shows, in addition to line D discussed above, the relation of percent paraflins to abrasion loss given in Table II for the asphalt Samples l1 to 13 and also for Samples -14 to 18. The lines are given only to indicate the trend of the dependence of abrasion resistance on percent parains and are not intended to imply a mathematical law.

FIGURE 3 shows the relation of the composition ratios of the asphalts of Table II Ito the abrasion loss by the shot abrasion test atfer weathering for 500 hours.

As in the case of 85-100 penetration grade asphalts, whose averages are plotted on FIGURE 1, the asphalts of 2004300 .penetration grade also show the dependence of abrasion loss on the composition ratio. Notwithstanding the differences in the methods of testing the abrasion loss and resistance to weathering, both tests show that an increase in the ratio N l-AI/P-l-A2 results in a decrease in durability of the asphalt as measured by either test.

Asphalts produced by blending gilsonite with an oil also show a reduction in abrasion loss with increasing paraflins content and decreasing N+Al/P-i-A2 composition ratio. They illustrate, however, the additional fact that an excessively low ratio, substantially below a ratio of about v0.4, indicating an excessively high concentration of paraflins and second acidatlins, reduces the lbonding power and results in a relatively high abrasion loss.

The following table illustrates this phenomenon:

10 just its ratio of N +A1/P+A2 to be within the desirable range. For asphalts of lower than about 100 penetration, the said desirable range is above 0.4 and less than its original ratio, if above about 1.5.

Experience has shown that, for 85-100` penetration paving grade asphalt, it is desirable for superior performance in the tield that the abrasion loss by the shot abrasion test be not over 50 grams/ 1000 grams of shot after weathering for 500 hours, and preferably should be much lower; and that the lower the abrasion loss by this test, the more durable is the asphalt. Pavements made of asphalt of 210 grams loss or less will last longer than those which show grams loss or higher, since the bonding power of the asphalts of 30 grams loss appear impaired as compared with the asphalt of 20 grams loss.

As will appear from FIG. 3, for 200-300 penetration grade asphalts, asphalts of ratio less than 1.35 will have an abrasion loss of less than 10 grams for the shot abrasion test after aging for 500 hours, and asphalts of ratio less than 1.7 will have an abrasion loss of less than 20 grams by the shot abrasion test after aging for 500 hours. From Table II (see Sample 18) the ratio may be substantially higher and give abrasion losses under 50 grams, and, as will be seen in the case of the gilsonite blends of Table III, ratios of as high as 1l for the ZOO-300 penetration grade also gave abrasion loss of under 50 grams.

Thus, asphalts of superior abrasion resistance are those whose composition ratios are more than about 0.4, and the upper limit of ratio for asphalts with good abrasion TABLE III Composition Percent by Wt. Abrasion Loss Gilson- N-l-Ar Shot Pellet ite Oil P A P+A2 Penetration Agrailon Average 2 38. 5 61. 5 39. 8 26. 1 0. 29 85 1 50 41 59 7. 1 29. 9 0. 4 85 27 11 16. 5 83. 5 1. 9 9. 9 10 87 86 100 65 43. 4 24. 3 24 134 0 50 37 63 7. 9 25. 7 37 132 10 1 11 89 l. 5 6. 7 11.8 149 57 100 3l. 5 68. 5 44. 5 20.1 22 229 0 0 34 66 8. 7 21. 8 32 249 4 1 3 97 1. 5 1. 6 l1. 257 37 49 1 Specimen aged in weathering machine before test. 2 Average of abrasion before and after 7 days' aging.

The data confirm the observations discussed above that for unweathered asphalts (asphalts containing 40% or less of paraiiins and having ratios of `0.4 or higher), the durability, as measured by either the shot abrasion test or the pellet test, as abrasion loss, increases with increase in the percent parains, and that asphalts with ratios of from 0.4 to 1.15 have abrasion losses by the pellet test of under 10%, and the abrasion loss increases rapidly with increase of ratio beyond 1.15.

The data show that, as a conservative measure, until `further research xes the effect of parains content in excess of 40% and ratios N +A1/P-I-A2 of less than 0.4, the desirable composition of unweathered asphalts to give superior durability, I conclude, are those having parafiins content of less than about 40% and ratios N -i-Al/P-l-Ag of more than about 0.4, and the asphalts of ratios from about 0.4 to about 1.5 will all have satisfactory durability. Asphalts of the 85-100 penetration grade with ratios above about 1.5 rapidly lose in abrasion resistance as the ratio increases.

It is, therefore, one object of my invention to improve asphalts, which are produced from a petroleum crude or a fraction thereof by distillation or blending an asphalt of relatively low penetration with maltenes, and which asphalts show a high abrasion loss and low durability, by adding to the asphalt a petroleum fraction which will adresistance depends on the penetration grade of the asphalt. For asphalts of or less penetration, the upper limit is suitably about 1.5, and for softer asphalts the ratio may be higher. Thus, in the penetration grade 200-300, the ratio is suitably less than 10. Also, the parains content is preferably below about 40% of the asphalt.

The abrasion loss of asphalts may be improved by incorporating, into the asphalt of relatively high ratio aud relatively high abrasion loss, fractions in quantity and amount to adjust the ratio to the desired value. Since this will cause some increase in the penetration value of the asphalt, it may be necessary, if the attained penetration :is undesirable, to either start with a low penetration asphalt, or employ as the blending oil an oil which has a high value of its P-i-Az fraction, minimizing the total amount of maltenes which is introduced.

The following illustrates the eifect of the concentration of the above fractions in the asphalt to be improved and of the oil used for the improvement.

If N+A1 and P-l-A2 are the concentrations of these fractions in the asphalt to be improved, and Ra is their ratio N-I-Al/P-i-A2; and N'+A'1 and P'l-A'2 are the concentrations of these fractions in the oil to be added, and Rf, is their ratio N\-A1/P'l-A2 in the oil employed;

R is the desired ratio which is to be attained for the asphalt to be improved.

The composition of the oil to be added will depend on the amounts of maltenes which may be added to obtain the desired penetration grade. This depends on the penetration value of the asphalt which it is desired to improve and the penetration value which is desired in the improved asphalt. It appears from the foregoing that the higher the concentration of the fractions P+A2 the less of the oil is necessary to obtain the reduction of the ratio R to a target value. The composition and the amount employed are regulated so as to produce an improved asphalt of desired penetration value, with a parafns content less than about 40% and a ratio R of more than about 0.4.

The previous examples illustrate the nature and amount of the maltenes which may -be employed for the 85-100 penetration grade asphalt.

Using the above equations, the amount of maltenes to be added may be calculated, if the composition of the asphalt to be improved and the composition of the maltenes to be added are known, and the desired value of R is specified.

It is an object of my invention to shift the composition ratio to a value closer to 0.4 than the value of the asphalt to be improved, which should be suiliciently reduced or raised in value to result in a substantial increase in the abrasion resistance.

Where the asphalt to be improved has a ratio substantially less than 0.4, I employ an oil having a ratio substantially higher than the ratio of the asphalt, preferably a ratio of 0.4 or higher. Where the asphalt to be improved has an excessively high ratio, I employ an oil having a substantially lower ratio.

By using maltenes of a ratio of about 0.4, I may improve asphalts of higher or lower ratio without rst determining the ratio of the asphalt, since if the ratio of the asphalt is in excess of 0.4, the oil Will reduce the ratio but not to or below 0.4. In treating asphalts of excessively low ratios, the 0.4 ratio maltenes will raise the ratio of the asphalt towards 0.4 and thus also improve the asphalt.

an R0 value less than that of the asphalt to -be improved, and preferably the lower this value the better; but the amount employed, and the parainic content, and the R0 value of the oil should not raise the parafnic content and lower the R value to undesirable limits, as stated above.

The oils should also be relatively high boiling petroleum fractions and substantially free of fractions boiling below about 160 C. at 10 mm. Hg absolute pressure, and preferably should have a distillation range whose initial value is about 200 C. at 10 mm. Hg absolute pressure (A.S.T.M. Test D-1160). It has been found that employing the lower boiling oils (notwithstanding they be of composition and be used in amounts to produce the desirable parans content, R ratio and penetration) produces asphalts of inferior durability according to the above tests. This is illustrated by the following data.

Sample 28 was made by blending the 32 penetration asphalt used in producing Samples 14-18. It was 'blended with a light spray oil extract in the following ratios by weight: 87.5% of the asphalt and 12.5% of the light spray oil extract. The spray oil extract had the following composition:

Percent Nitrogen bases 5.9 First acidans 14.6 Second acidans 58.8

Paralins 20.7 N-l-Al/P-l-AZ 0.258

The oil had the following distillation range:

Initial 170 229 End point 253 The blended asphalt had the following composition and properties:

Percent Asphaltenes 11.0 Nitrogen bases 38.7 First acida'lns 15.6 Second acidaflins 21.5

Parans 13.2

N-t-Al/P-t-AZ 1.56 Abrasion loss, shot abrasion test 41.8

This may be compared with Sample 16 above, in which a medium lubricating oil extract was employed to give an asphalt of similar composition, both as to parains content as well as R value, and vboth having a ratio of about 1.5.

A similar result is obtained by employing a technical white oil (98% unsulfonated residue) of 100 Saybolt seconds at 100 F.

Sample 29 was produced by blending 89% by weight of TABLE IV 32 Pon. Asphalt Maltencs Improved Asphalt;

Composition Composition Composition Shot abrasion test P Ra P R0 P R loss after 500 hrs.

The above Table IV illustrates the effect of the R0 the above 32 penetration asphalt with 11% by weight of value of the oil. It is apparent that the oil should have the above technical White oil.

The white oil had the following composition:

treated with the maltenes a (Method I); Bb is the IB asphalt treated with the maltenes b (Method II). The

Percent Nitrogen bases asphalts. so treated were again aged for 650 hours 1n the First acidafns 0 1 weathering machine and tested by the shot abrasion test. Second acidamns 3 5 The Compositlon of maltenes a employed in Method I Paramus 94.6 andh tleumaltenesblb employed in Method II are given N A P inte oowingta e:

1/ LAZ 0'01 Table v1 The -distillation range was the same as for the spray oil Maltenes a (Method I): Percent extract of Sample 28. N 17 The resultant asphalt had the following composition A1 17 and abrasion loss by the shot abrasion test: A2 54 Percent P 12 Asphaltenes 10.4 'R 0.52 Nitrogen bases 38.4 15 Maltenes b (Method II) First acidatiins 12.7 N 3.5 Second acidafiins 18.2 A1 6.5 Paraffins 20.3 Az 28 N-l-A1/P|-A2 1.33 P 62 Abrasion loss 23.5 R 0.11

TABLE V Maltenes Asphalt Shot Composition Distillation Range l Composition baintrsr P R Initial, o. 50%, o. E P., o. P n e o. 2s 17o 229 253 13. 2 1. 56 42 o. 53 205 263 295 11.9 1. 43 3 0.01 17o 229 253 20.3 1. 3a 24 o. 41 244 322 325 19. 1 1. 24 5 1 At 10 mm. (Hg) absolute pressure.

This may be compared with Sample 15, which resulted in an asphalt of similar composition, both in paraflns content and ratio. These results are tabulated above.

It thus appears that, even though the oil to be employed has snicient concentrations of parafiins and also second acidafns to have the desirable R ratio so that one may obtain the desired R ratio in the blanded asphalt and give the desired penetration, it will not achieve the same low value of the abrasion loss if it contains volatile components so that its initial boiling point in the above tests is substantially below 160 C., at 10 mm. Hg pressure absolute. Itshould be preferably substantially free of fractions boiling below about 200 C. at such pressure. By substantially free, as used in this connection in the specification and claims, I mean that the oil should not contain fractions boiling below about 200, in Vamounts sufficient to result in an undesirable increase in abrasion loss.

The above observations were all related to the effect f of the chemical composition of unweathered asphalts on the properties of the asphalt, particularly their durability when exposed to weathering as measured by the test procedures described above.

Studies in the behavior of asphalts during weathering and the changes which occur in chemical composition, and the beneficial effects of blending weathered asphalts with maltenes, have produced the following surprising results.

Two asphalts, identified as asphalt A (same as Sample 18) and asphalt B (same as Sample 16) were Weathered, and the weathered asphalt was blended each with two different maltenes having different compositions.

The asphalt, after being subjected to weathering for 650 hours in the weathering machine, was tested for abrasion loss b-y the shot abrasion test and analyzed. The weathered asphalt from A is given below as A', and the weathered asphalt from B is B'.

One portion was treated with an aqueous emulsion of maltenes containing 60% by weight of maltenes a (Method I), and another by a different maltenes b (Method II). This gave four asphalts. Asphalt Aa is the weathered A asphalt treated with the maltenes a (Method I); Ab is the weathered A asphalttreated with the maltenes b I(Method II); Ba is the weathered B asphalt The emulsier was a fatty quaternary ammonium salt 0.7% by weight (cationic emulsiiier) and a nonionic emulsier (alkylphenylethylene oxide condensation product)0.5% by Weight of the emulsion.

The results are tabulated below.

1 Weathered for 650 hours, shot abrasion test. 2 Aged an additional 650 hours after treatement.

Comparing asphalt A, which on aging had an abrasion loss of 37 by the shot method, with the asphalt B, which showed 8, reveals the influence of the parafns content and the R ratio, as previously explained.

This is also revealed by comparing the percent paraffns and the R ratio 4of the asphalts Aa, Ab, Ba and Bb with their abrasion values. It also reveals that the asphalt with the higher R ratio and lower paraftlns content shows the higher abrasion.

The low Values of the abrasion losses for Ab, -B'a and B'b are surprising. Thus, the improvement obtained em ploying maltenes b (asphalt Ab) gave an asphalt with an abrasion value of 4. The increase in the durability of the asphalt reflects the increase in the paraflins content and reduction in the R ratio, although the increase in the durability is in excess of what would be expected for an unweathered asphalt. The same phenomenon appears with the B series. The reclaimed asphalts Ba and Bb both have relatively low values of R and show lower abrasion loss, the treated asphalt showing a better durability, i.e., lower abrasion loss, after treatment compared with the original asphalt.

I may rejuvenate weathered asphalts by incorporating into the asphalt petroleum fractions of such composition and amount as to reduce the R ratio of the asphalt and can thus rejuvenate a weathered road and obtain a pavement having an even greater durability than when the road was freshly laid.

Field experience confirms this result. A roadl which had been Weathered for two years was divided into three sections; one was as is, the second was treated with 0.11 gallon/square yard with the cationic maltenes emulsion described below, and the third was treated with 0.22 gallon/square yard of the same emulsion. The untreated section and the treated sections were cored to a 3/8" depth, i.e., top or surface section; a second core was taken to a further depth of about 1, i.e., the middle section of the road. The cores were then extracted by the following procedure.

A sample of asphaltic paving material is first heated to a temperature of approximately 140 F. by any convenient means, as in an oven or over a steam plate. At this temperature most samples can be crumbled by hand. Extremely hard samples may require the use of pliers or a hammer. The sample should be reduced to about BA" pieces or to the size of the largest pieces of aggregate, whichever is larger. Care should be taken not to break up the rocks and stones of the aggregate, so that the grading of the aggregate can be determined by sieve analysis on the sample after extraction.

The crumbled material is iirst weighed and then is placed into extraction thimbles of a Soxhlet extraction apparatus and covered with a loose plug of absorbent cotton to retain the aggregate. A thimble found suitable is a Whatman single thickness 43 123 mm. thimble. The asphalt is extracted in the Soxhlet apparatus with benzol until the benzol in the extraction chamber is colorless. The benzol extract is filtered as some of the liner aggregate passes through the single-thickness extraction thimbles. One may employ a 6-inch funnel using Whatman #1, 24 cm. filter paper or any other suitable iilter. The benzol is distilled oit from the extracted asphalt by heating the iiask of the distilling apparatus in an electrically heated wax bath or oil bath at 150 lC. Last traces of benzol are removed by carefully applying vacuum to the distilling apparatus while continuing to heat the flask in the wax bath at 150 C. The weight of the asphalt in the ask may be determined. This asphalt is herein referred to as extract asphalt.

The maltenes in the emulsion employed contained about 26% parains and had an R0 ratio of about .4. They were employed in a 2:1 ratio of concentrate to water. The emulsion concentrate contained 60% by weight maltenes and 0.9% of a cationic emulsitier (fatty amidoamino amine propionate, Promeen 2115, Process Chemical Co.) and 0.9% of a nonionic emulsier (dodecyl phenol polyethoxy ethanol, Pronon 280, Process Chemical Co.), and the balance water. This emulsion was employed in the tests hereinafter referred to, unless otherwise specified.

The results are tabulated in Table VI-LI.

to increase the paraffins content, and particularly by adjusting the R ratio of the bonding asphalt.

It is thus an object of my invention to improve the weathering resistance of asphalts, whether originally weathered or unweathered, by treating the asphalt with a petroleum fraction to adjust the R ratio of the asphalt to reduce the R ratio if the R ratio is excessively high, for example, substantially above 1.5, or increase the R ratio if it is less than about 0.4, to a value in the range of about 0.4 to about 1.5.

The improvement attained in the road described above resulted from the reduction in R ratio by the treatment.

Where a weathered road contains weathered asphalt of excessively low R ratio, it may be reclaimed by treating the road by the application of a maltene-s emulsion of a higher R ratio than that of the weathered asphalt. A road so treated was successfully reclaimed by this process, as illustrated by Example 6 given below.

As a rule, paraiiins content is also increased by the treatment, but should not exceed about 40% of the asphalt.

I may employ any petroleum oil fraction, substantially free of asphaltenes, containing parains and containing members chosen from the group of the nitrogen bases, first acidatiins, and second acidafiins that is, with or without the presence of one or more than one of the following: first acidaiiins, second acidaiiins or nitrogen bases. I may also employ oils containing second acidaiins with or without paraliins, first acidatlins or nitrogen bases. As a practical matter, petroleum oils will usually contain both paralfins and second acidains, and may also contain nitrogen bases and first acidafiins or one of the latter two members.

Such maltenes fractions may be produced from petroleum oils by removing the asphaltenes and wax of the oil (it the oil is a waxy oil) from the oil thereof to produce fractions which have about 5% to about 95% of parafiins components, with or without second acidaffins, the remainder being the more reactive components, to wit, the nitrogen bases and the iirst acidaiiins, and having a R ratio of from less than 0.01 to about 19. Since the purpose of my invention is to add components chosen from the group of paratiins and second acidaiiins and, if necessary, enough of the more reactive components, to wit, components chosen from the group of the nitrogen bases and first acidaflins, to peptize and dissolve the asphaltenes, I prefer to employ, as described above, a petroleum fraction which has the required concentrations of these components.

The composition of the oil will be determined by the considerations previously described. Examples of suitable oils which may be employed are given above. The following further examples of oils are given as illustrations of oils for use in emulsion form for reclaiming weathered TABLE VIII Core Identification Section Untreated Treated (0.11 g.s.y.) Treated (0.22 g.s.y.)

Top Middle Top Middle Top Middle Asphalt content, by Soxhlet Extraction, percent aggregate weight 3.8 4. 4 5. 2 4. 9 5.0 5. 0 Viscosity, megapoises 37. 3 14. 3 14.0 24. 3 2. 7 22.0 Penetration Value, 0.1 11u11 17 26 26 20 56 22 Chemical Composition (Rostler Method); Percent by Weight:

Asphaltenes 25. 8 20. 6 25. 5 21. 9 24. 9 22. 8 Nitrogen Bases-- 31. 9 35. 3 29. 7 34.6 28.1 34. 7 10. 2 12.8 10. 9 12. 7 10. 4 11. 9 18. 3 17. 2 18. 7 16. 7 19. 9 16. 2 13. 8 14. 1 15. 2 14. 1 16. 7 14. 4 Pellet Abrasion Test Percent Loss in Vl gh As Recovered 64 27 8 42 1 42 Aged 1 100 72 39 88 4 90 Ratio (R), N-I-Ar/P-l-A2 1. 31 1. 64 1. 20 1. 54 1. 05 1. 52

1 i.e., after weathering as reported in Rostler and White article.

The road surface after treatment was in excellent live condition.

The road test confirms the above results that a weathered asphalt may be improved and `a weathered asphaltic structure may be reclaimed by adding petroleum fractions l 7 Parafns.-From about 20% to 85 by weight; Second acidaflins.-Balance to make up 100%.

Another example of a suitable oil is one containing: Nitrogen bases.-Not more than about 35% by weight; Paraffinic fractions-From about 20% to 85% by weight;

18 A further observation is that, if the asphalt to be improved has a ratio Ra in excess of .4, the value of R is taken as less than Ra; and if the value of Ra be less than .4, the value of RD should be greater than Ra.

In treating roads or other asphaltic structures, it is First and second acidaffins.-Balance to make up 100% 5 desirable to employ the maltenes in an emulsion form, as

by weight. will be described below. Another example of a suitable oil is one having: The signicant importance of an emulsion form of a Nitrogen bases and first acidains.-Not more than about reclaiming agent for weathered asphaltic pavement arises 35% by weight; 10 from the effect of the emulsifier to condition the asphaltic Paraffinic and second acidains.-Balance to make up structure and the asphalt phase of the structure, as well 100% by weight; as the oil phase of the emulsion, to permit the incorporaprovided that the paraffinic fraction is in the range of tion of the maltenes phase into the asphalt. about 20% to 85% by weight of the oil. Two different phenomena Iare to be distinguished. One Another example of a suitable oil is one containing: is the flow of the emulsion fluid through the pores of the Nitrogen bases and first acidaffins.-Not more than 20% asphaltic concrete, i.e., the voids between the aggregate' by weight; particles bonded by the asphalt, and the other the absorp- Parafiins and second acidainsr-More than 80% by tion of the maltenes phase from the emulsion into the weight; asphalt phase to change the chemical composition of the the total forming 100%, provided the parainic fraction 20 asphalt. is within the range of to 80% by weight. One of the controlling factors is that the emulsion pene- Other suitable oils are as follows: trates the surface of the asphaltic structure and passes TABLE IX into the pores of the asphaltic structure -but not through the structure before the emulsified maltenes are stripped Specific Gravity, Q0" F./60 F 1. 015 .997 1.028 .966 .957 25 by the asphalt from the emulsion. isslicqry:"jjj:j: 237g l igz) 423g 133?) d In ttrieat-ing road tsurfaces for 1lpurpises I cf f econontrgl, it is sp atenas esire to treat t e top Wea ere su ace so at its gruilm-Hs-j f j 45j? gjl 194,913 plasticity may be restored. The surface, on rolling either Ratio N+A1/P+A2 .55 .36 1.1 .41 .28 by rollers or by traflic, is thus ironed out and cracks 1 At atmospheric pressure. 30 sealed. This preserves the underneath structure2 It is unh b h b 1, desirable and wasteful to use a treatment which either AS a @O nvement rule of t um dt eb Og 01111; at makes a superficial glaze or runs through the road strucatmospherlc Pressure may be assugnel to e a Ove ture from top to the base. Usually it is suficient to. rethat at 10 mm' (Hg) Presure a Sg um f b juvenate about the first 1A to 1 inch of the road surface. The R00 Value of the Q11 may t us range mm a out 35 This effectively rejuvenates the road and does not waste 0.01 to about 10, the ratlo R0 chosen dependlng on the the emulsion muohof tg@ aphaltdtne miproggnarii tonhthe rlulot If the pavement is badly weathered and cracked, the Sqlllg t to de o 'me efam) Od 0 thelas? i; emulsion will penetrate to the region of weather damage w1 l depen ont e penetration gra e o e asp at 0 e and rejuvenate the weathered asphalt portion of the asimproved and the penetration of the improved asphalt 40 phaltic Structure which 1S deslri Thusl lf Ra Ofddtll asplaltztc? be nglflvid The preferred practice is to use an amount of emulsion 1S known. an. s c Osen an e ra lo 1S es a 1s e of the above concentration, i.e., about 40% oil phase, in the equauon at least an amount per square yard which the road will Z: (P -i-z) (Rf-R) I absorb in about fifteen minutes. In cases where early re- (Pl-A2) (R-R0) 45 sumpt-ion of trafiic is not a requirement, larger amounts l may be used. Will establish the Ro 0f the 011 Whlch may be USd- This phenomenon is not entirely a viscosity effect, al-

The addition of the maltenes to the asphalt w1ll reduce though visgsity does affect the penetration through the the PCHeUaOH 0f fh@ asphalt, and thus The ratio Z S (16 pores of the structure. The viscosity of the emulsion, pendent on the penetration of the asphalt and on the penewhich is substantially that of water, does not control the tration desired for the improved asphalt. absorption of the maltenes from the emulsion phase by In the usual case, this ratio Z will be such as to estabthe asphalt phase of the structure. lish the required penetration grade, to wit, usually, for The following Table X illustrates the effect of the emulpaving asphalts, in the -100 grade or 20G-300 grade. F sion type on the absorption of the maltenes into the as- However, `where special asphalts are desired, other pene- 5U phalt as it enters the asphaltic structure. It also shows the trations may be required, and the value of Z is suitably difference in the effect of other fluids, as named incolunm adjusted. 2 of the table.

TABLE X Time for Treating Fluid Depth of permeatlon Time of penetration for 10 ml. 0i penetration oi 10 ml. Test No. Description Viscosity treating fluid of treating Aerosol OT m cp. ud in solution into inches treated briquet 1 Control 12 sec.

0.89 18min. 0.88 16 min. 0.89 18 min. (3) 19 min. 0. 22 min. None 48 min.

o. 45 0.83 Smin. Kerosene 0. 97 2 min. Oil in kerosene-.. 0.84 4min. 12 Tap water (4) 2l sec.

1 Treating fluid in these tests have same diluent concentration.

3 Ran through briquet and out bottom.

tration of fluid.

4 Not measurable.

2 Briquet collapsed after 11 to 12 hrs., before complete pene- The specimens used in the tests summarized in Table X were molded briquets, 2.5 inches in diameter, 1.6 inches high, with a 2-inch diameter, 0.318-inch deep reservoir pressed into the top side. The mixture used to form the briquets consisted of 90 parts by weight of 20-30 mesh Ottawa sand (ASTM C-l09), 10 parts portland cement, and 7.5 parts asphalt of lit-penetration.

The cationic emulsion was formed using the cationic and nonionic emuls-ifiers as described above. (See Table X.) The nonionic emulsions `were formed using only the nonionic emulsifier (.8% by weight). The anionic emulsions were formed using only anionic emulsifier (1.2% by weight of a sodium petroleum sulfonate).

The test procedure employed was to place the test fluid in the reservoir on the top of the briquet and to split the briquet after 24 hours, to determine the depth of penetration by inspection under ult-ra-violet light. The portions of the briquet reached by the treating agent fluoresce when illuminated with ultra-violet light.

It is evident from the test results reported in Table X that a -relatively rapid rate of penetration was obtained with all forms of emulsion systems, except the asphalt emulsion (grade SS-l, diluted 2:1 `with water), which did not penetrate but formed an asphalt skin at the surface when the water phase evaporated. This notwithstanding that the asphalt emulsion had the same viscosity as the oil emulsions. Further, the anionic emulsion penetrated so easily that it ran through the briquet, and thus the contained oil was not utilized. This is in contradistinction to the cationic and nonionic emulsions.

The fact that viscosity is of minor consequence for peneration may further be seen by comparing 11 with 3, in that both fluids had the same viscosity and depth of penetration, but the kerosene-oil mixture penetrated much more slowly.

The oils or cut-back asphalts which are not diluted but are used directly are also not suitable in such form for rejuvenating of weathered roads, since their penetration into the asphalt structure is limited. The same may be said of asphalt emulsion. At -best they act merely as a surface coating in the form of a paint. This is illustrated by 7 and 9.

For purposes of comparison, results are also lgiven for kerosene by itself, MC-70 liquid asphalt cutback, and tap water.

It is interesting to note that the briquets were relatively impervious to plain tap water but that, with the wetting agent added, water penetrated the briquets readily. The Water with the wetting agent even penetrated the briquets that were treated, but at a much slower rate. This serves as a measure of the relative effect on pavement permeability of the various listed treatments, as shown in the last column in Table X.

The duplicate briquets, each separately treated as in the above series, were weathered for 7 days as for the pellet abrasion test. The test method employed consisted of placing the l milliliters of the Aerosol OT solution (dioctyl ester of sodium sulfo succinic acid) into the reservoir on top of the briquet and measuring the time for the penetration of the liquid into the briquet. The results reported in Table X show that all emulsion systems tested are more effective in decreasing the permeability of a weathered asphalt-aggregate mixture to the water containing the OT surfactant than are the kerosene cutbacks. Moreover, although the SS-l asphalt emulsion formed a membrane, water still managed to permeate the structure.

Control 1 is untreated. The permeability of the briquet to the iluid is evidenced by the time of penetration of the fluid through the briquet. Thus, for the untreated briquet (l) the penetration time' was 12 seconds, using the Aero- 20 sol OT water solution. The briquet treated with water required 21 seconds. The time for the weathered asphalt treated with the oil emulsions varied from 16 to 22 seconds, that for the nonionic emulsions being slower than the cationic emulsion containing also the nonionic emulsifier.

In addition to the tests reported in Table X, a number of other fluids were tested to check on the importance of the emulsification system. One of these tests was the use of a straight cationic emulsion, i.e., an emulsion the same as used in test 3 but not containing a nonionic emulsifier, only the cationic. The viscosity was substantially the same (14 centipoises), but the time of penetration for l0 ml. of the treating fluid into the briquet was 162 seconds. The depth of penetration was 0.81 inch. The time of permeation of 10 ml. of Aerosol OT solution in the aged treated briquet was 21 minutes. A comparison of these figures with those shown in Table X for test 3 demonstrates the difference between a cationic-nonionic emulsiiication system and a straight cationic. Depth of penetration was slightly less for the straight cationic system, but the time of penetration was about 3 times that of he nonionic-cationic system. The slower permeation of the Aerosol OT solution into the briquet treated with the straight cationic emulsion can be explained by the more eflicient stripping of the maltenes from the emulsion by the asphalt, as evidenced by the lower depth of penetration into the briquet and thus increased density of the treated portion of the briquet.

The above data is further evidence that the effect of the oil emulsion on asphaltic concrete is not a viscosity eifect, but is strongly affected by the nature of the systems, the oil emulsion system showing a markedly different and more rapid penetration than do other systems of similar viscosity, resulting in less permeable structures.

This effect is further demonstrated by actual `field test experience. A weathered road was treated with a cationic emulsion containing additionally a nonionic emulsifier similar to that employed in the test shown in Table X.

A weathered asphaltic road was treated in sections with a 2:1 dilution of a cationic maltenes emulsion containing nonionic emulsifier, such as described in connection with Table X, employing 0.06 gallon/square yard, 0.14 gallon per square yard, and an excess quantity, approximately 0.25 gallon per square yard. Another section was treated with conventional ashalt emulsion SS-lh (slow setting emulsion containing 60 penetration asphalt), with a dilution of approximately 3:2 at the rate of 0.1 gallon per square yard. A section was left untreated.

From visual observations during application, it was evident that the diluted maltenes emulsion penetrated into 4the Ve-year-old pavement quite readily, with complete penetration being accomplished within five to twenty minutes, depending on the rate of spread. Since this pavement had not previously `been sealed, and since there were no accumulations of grease drippings, no sanding was required. On the other hand, the asphalt emulsion did not penetrate, and sanding was required for safety reasons and to prevent pick-up of the asphalt by trafc.

Two months after application, cores were taken from the various sections `and cut horizontally at 1/z-inch intervals. Viscosities of the asphalt recovered from each slice were -then determined using the sliding plate microviscometer, manufactured by Hallikainen Instruments, Berkeley, Calif. See articles by Labout and Van Ort in Anal. Chem., vol. 28, 1147-1151 (1956) and Griffen, et al., in Road and Paving Materials (A.S.T.M.) Special Technical Publication 212 (1957), pages 36-50. Table XI is a tabulation of the viscosities measured and the penetration (given in parentheses) derived from the viscosities. (See Pfeiffer, The Properties of Asphaltic Bitumens, published by Elsevier, New York, 1950, p.

TABLE XI.-VISCOSITY OF RECOVERED ASPHALT,

MEGAPOISES Cationic Maltenes Emulsion, Asphalt diluted 2:1 Emulsion Depth,

in. Untreated SS l-h,

0.06 g.s.y. 0.14 g.s.y. 0.25 g.s.y. dilution (approx.) 2:1

0.1 g.s.y.

No'rE.-Numbers in parenthesis are penetration values of asphalte obtained by conversion. See text.

It is quite apparent from Table XI that the treatment with the maltenes emulsion has caused a significant change in asphalt viscosity present in the pavement to a depth of at least lz inch, with a possible eifect of the added maltenes to a depth 0f 1% inches for the heavier treatments. Since these results were from cores taken relatively soon after application (approximately two months), it is possible that the maltenes had not yet had sufficient time to reach a state of equilibrium with the asphalt. In the case of the asphalt emulsion of substantially the same viscosity, no such effect is observed.

The cationic emulsion of the maltenes produces asphaltic structures of improved cohesiveness as compared to other dilution systems. They have improved load-penetration characteristics. Tests were run on the same type of briquet used in comparing rates and depths of liquidpenetration. (See Table X.) An apparatus was used which would apply load to the treated end of the briquet through a 1.128 in. diameter (1.0 sq. in.) piston at a strain rate of 0.25 in. per minute to a total deformation of 0.250 in. The data obtained from this test are relative but valid for the series of briquets tested. Resulting load vs. deformation diagrams were obtained and are shown in FIG. 5.

In order to establish reference points on the chart, two load-deformation curves are shown for freshly mixed briquets made with 71/2 percent by weight of 48 penetration and 200-300 penetration asphalts. All other curves represent various treatments of a reference briquet made with 48 penetration asphalt at various states of aging. The aging of the briquets was accomplished in the infrared oven described in the article by Rostler and White, supra. The oven is automatically controlled so that the temperature within the briquets themselves is maintained at 140 F. during the specified aging time.

From FIG. 5 it is evident that kerosene used as a carrier destroys the cohesiveness of asphalt binder and that proper cohesion cannot be regained even after 14 days of exposure at 140 F. in the infra-red oven because the kerosene has dislocated the asphalt cement located between the points of aggregate contact. In contrast, the emulsion system used for introducing the maltenes does not displace the asphalt providing the bonds between aggregate particles in the briquets, as evidenced by the fact that in all cases the briquets have resistance to load penetration exceeding that of 200-3 00 penetration asphalt, although the consistency of the binder (asphalt) has been lowered.

From laboratory studies similar to those described above and from field experience in applying various emulsions to pavements, it has been con-eluded that the best method for incorporating the maltenes into the weathered asphalt concrete, as in road pavement, is in the form of a fine particle size, cationic emulsion, containing a nonionic emulsiiier, as described. Although a dilution rate of two parts of emulsion concentrate to one part of water (40%. oil content) is preferred to get the best combination of penetration rate and economy, the dilution rate to lt each particular job should be chosen on the basis of job conditions.

The importance of the emulsion system as affecting the particle charge is shown by the following.

One series of tests was designed to determine the importance of particle charge, as related to the adhesion characteristics of the asphalt-aggregate system. The test consisted of placing 2 g. pellets made by mixing 100 parts Ottawa sand and two parts -100 penetration asphalt, aged for seven days in the infra-red oven at F., into beakers containing 50 ml. distilled water and heating the water to the boiling point. For this test several pellets were prepared and tested after treatment with 0.06 g. of the maltenes. The oil was applied as a cationicnonionic emulsion, described above, and as a nonionic emulsion, undiluted, and as a solution in kerosene. The pellets, after aging for seven days in the infra-red oven at 140 F., were immersed in 50 milliliters of water, the water heated to boiling, and the contents of the beaker filtered through a No. 1 Whatman filter paper. The stripping etfect was evaluated by observing the amount of asphalt floating at the water surface and clinging to the beaker walls, as well as by noting the area of exposed aggregate surfaces on the Ottawa sand at the bottom of the beaker.

The relative effect of the test on stripping of the asphalt could be readily observed visually. Most of the asphalt was stripped off the sand grains in the untreated control pellet and all of the other treated pellets, except the one treated with the cationic emulsion of the maltenes, where very little stripping was noted. The stripping that was observed in the cationic sample was due to asphalt stripped from the bottom of the pellet where the treatment did not reach.

Another test consisted in examining under a microscope fragments of the treated pellets in order to observe the effect of the treatment and aging procedure on the asphalt cementing the sand grains in the pellets. Improvement in the bonding accomplished by the cationic emulsiiication system, which causes the oil to wet preferentially the asphalt portion of the asphalt-sand mixture, Was readily observable.

This microscopic examination showed that the nonionic emulsion system does little to increase the bond because there is no preferential wetting of the asphalt portion. The undiluted maltenes result in droplets of uncombined oily material attached to the sand grains.

With kerosene as a carrier for the oil, the asphalt films are washed from the sand grains and are accumulated in the voids between them, resulting in loss of bond at the points of contact.

The advantageous results obtained from using the above combination of emulsitiers is additionally shown in the following tests.

Abrasion test pellets were prepared in accordance with the pellet test procedure referred to above, using a 48- penetr-ation `asphalt and 20-30 mesh Ottawa sand. Duplicate pellets without treatment, and also duplicate pellets treated with aqueous emulsions of the maltenes in the same concentration of maltenes but differing only in the emulsion system, were subjected to the following tests. The cationic emulsion was that previously described containing nonionic emulsiiier. The nonionic emulsion was made from the noniomc emulsiiier alone, and the anionic emulsion contained only an anionic emulsifier. The pellets were then aged in the infrared cabinet for seven days (see Rostler and White, supra). After exposure in the infrared oven employed in the above procedure, the weathered pellets were subjected to an abrasion test by tumbling them in a 16-oz. French square bottle for 500 revolutions, as in the above pellet test.

Table XII summarizes the results obtained in this abrasion test.

TABLE XII.-PELLET ABRASION TEST RESULTS Abrasion loss, percent Anionic Emulsion It will be seen from the above results that the cationic emulsion showed a considerably greater improvement in the abrasion loss after 7 days as compared with the other emulsion systems, the cationic emulsion showing a 62% reduction, the nonionic emulsion a 44% reduction, and the `anionic emulsion a 35% reduction in the abrasion loss.

The effect of the maltenes in the cationic-nonionic emulsion form in modifying the asphaltic phase of an asphaltic pavement is further illustrated by Table XIII, showing waters. The emulsion is stable in the sense that it will not break when stored for long periods in clean, closed containers at ordinary atmospheric temperature above freezing. Additional water may be introduced into the emulsion prior to time of application.

I have found that the best results are obtained by using a balanced type emulsion, as described above. The emulsifiers to be employed are preferably surfactants which are stable under the conditions employed in making the emulsion, and which will not break immediately when applied l0 the effect of this treatment on the permeability of the to the road or other asphaltic structure being reclaimed, road pavement to water. so as to penetrate the asphalt and release the oil phase,

TABLE XIII Water Permeability, Station Mls./Min.

OWT BWT IWT Section treated with A.

emulsion.

Test Section.

catiomc-noniome-Maltenes Control Section. Rolling consisted 0l breakdown with 12 T tandom+3 c0verases with 26 T pneumatic followed with 8 T tandem. Section 2.

Ave 93 Total Ave OWT=outer wheel tracks.

BWT=bctwcen wheel tracks.

IWT=inner wheel tracks.

Tests were made by treating a road to ascertain the effect of the emulsion on the Water permeability of a newly compacted aspalt pavement. In Table XIII are given water permeability results from tests conducted on the pavement immediately after final compaction. All water permeability tests were run on the surface course using the method described in California Test Method 34l-A.

As seen in Table XIII, the test section with the maltenes emulsion treatment has had its water permeability reduced to about 53 percent ot the untreated control section. This is an extremely important feature of the maltenes emulsion treatment, particularly when one considers the cornpaction effort required to reduce the permeability to a similar degree. Moreover, the decrease in permeability has been achieved in a finite depth of the pavement, and not by a skin coating which can readily be worn away by weather and traffic.

The superiority of the balanced emulsions containing the blend of the cationic emulsitier and the nonionic emulsier, as shown by the above tests, is confirmed by actual field experience.

These cationic emulsions have the additional superiority that they are stable and may be mixed with hard water and even sea water without breaking the emulsion.

I have found that, for the purposes of my invention, the emulsion should preferably have the following characteristics: It should be free-liowing, preferably within the range of 57 to 63 parts of the oily component by weight, and water as the continuous phase not less than about parts by weight and preferably in the range of 37 to 43 parts by weight, and also an emulsiiier. .Water employed may be distilled water, or ordinary soft or hard i.e., the maltenes, within the asphalt structure, to become incorporated into the Weathered asphalt.

The surfactant compounds having properties previously described are listed in standard textbooks in this art, for example, the Encyclopedia of Surface Active Agents, by Sisley and Wood, published by the Chemical Publishing Company, Inc., New York. The cationic emulsifying agents employed may be, for example, Cetylpyridinium chloride, or other quaternary ammonium salts and other cationic surfactants listed in the above publication and other standard books on the subject. These include the aliphatic fatty amines and their derivatives, the homologues of the aromatic amines having fatty chains (see pages 35, etc., -104l of the 1952 edition of the above publication). Nonionic emulsifying agents such as are described above, and others which have the properties previously described, may be employed, such as are listed in the above textbook, at pages 119-123 and page 163, etc.

Suitable nonionic emulsiers which have been employed are nonionic surfactant sold by Process Chemical Company as Pronon 280, and as Oronite NI-W by the Oronite Chemical Company, and believed to be dodecyl phenol polyethoxyethanol. Suitable cationic emulsifiers are the fatty quaternary ammonium salts, fatty amido-aminoamine salts of the lower fatty acids sold by Process Chemical Company as Promine 2118, and believed to be a fatty amido-aminoamine acetate, and also the propionate salt sold as Promine 2115.

This list is not intended t0 be exhaustive, and is but suggestive of the emulsifying agents which may be employed. Many agents useful for emulsifying petroleum oils are effective in various concentrations.

In addition to the emulsifying agent, stabilizers may be used to stabilize the emulsion against electrolytes which may be present in the water used for making or diluting the emulsion.

The emulsion has the surprising result discussed above, in that it causes a rapid penetration of the reclaiming agent into the weathered structure, such as a weathered road. The rate of penetration depends also on the porosity of the road. This depends on the density, i.e., the compaction of the road when laid down, the grading of the aggregate, the original asphalt content of the road and the degree of weathering. Depending on these factors, the emulsitied maltenes of my invention will be absorbed from almost instantaneously up to about 2 days, depending upon the volume per unit area of road. Unemulsied maltenes applied in equivalent volume rate calculated as oil, on a like road surface, will, experience has shown, take from several hours to a week or more, and in some cases will not be absorbed at all. During all this period the road is slick and unsafe for trac.

Highway regulations in California require two lanes to be opened by Sundown, and for many roads this is not possible, using unemulsified oil; whereas with an emulsion used according to my invention, such penetration is achieved.

When using an emulsion made with a nonionic emulsication system on processed roads which had a large amount of dirt and dust incorporated by the breaking up process, the emulsion appeared to preferentially wet the unoiled aggregate and dirt and acted as a dust-layer and did not penetrate the asphalt very well. When the emulsion is made with a cationic emulsier, the weathered asphaltcoated surfaces are preferentially wetted, but a mixed cationic-nonionic emulsication system is preferred because it provides a balance of desirable properties, to wit: ease of emulsiication; stability in storage and application; rapid penetration; preferential wetting of asphalt rather than of aggregate; and a water-repellant surface on the reclaimed structure.

I have found that materially improved results may be obtained by employing a balanced emulsion. By a balanced emulsion I mean an oil and water emulsion stable against electrolytes present in hard water and containing nonionic surfactants and cationic surfactants in amounts suflicient to form an emulsion of cationic character, i.e., one in which the oil phase will deposit on the negative electrode if the emulsion is subjected to electrophoresis. Thus, the preferred emulsion will contain in parts by weight, based upon the oil phase of the emulsion, nonionic surfactants from 0.5 to 2% and cationic surfactants from 0.5% to 1.5%. Preferably the surfactant should be employed in the emulsion in an amount, based upon the oil phase, such that the nonionic surfactants are preferably about 0.7% or more by weight and cationic surfactants of 0.5% or more. Such an emulsion system will wet the asphalt portion of the road surface preferentially over the wetting of the aggregate and penetrate into the capillaries of the wetted asphalt at a more rapid rate than if no nonionic surfactant were employed.

For the purpose of convenience, I prepare the emulsion in the above concentrations. Before applying the emulsion to the road, I may dilute the emulsion, for example, with an equal amount of water, although higher or lower dilutions may be employed.

The amount of maltenes to be added to the weathered asphalt depends on the nature of the weathered asphalt. In the case of an asphaltic pavement, the amount of the maltenes to be added should be not so great as to make the pavement unstable and should not exceed the safe asphalt content of the road, nor be used in an amount such as to cause syneresis, i.e., oil exudation. Additionally, the amounts added should be sufficient to improve the quality of the road or other asphaltic structure above that of the weathered road or structure, but not in such large quantity as to exceed, in the case of a road or other asphaltic structure, the capacity of the road or other structure to absorb the fluid applied, as will be described below. The amount of the total asphalt should not exceed the safe holding power of the aggregate. If it is exceeded, the asphalt will exude as a separate phase and not be incorporated into the asphaltic structure. Various authorities specify the particular composition of asphalt pavement, and thus determine the quantity of asphalt to be contained in the asphalt pavement.

Standard Specifications issued by the Division of Highways, Department of Public Works, State of California, dated August 1954, gives at page 321, etc., the properties of various asphalts which were acceptable to the -State of California. See also Asphalts and Allied Substances, by Abraham, 5th ed., vol. l, page 643, published by D. Van Nostrand & Co. The particular penetration grade asphalt found acceptable for any specic road job is usually specified by the engineer on the job or by contract. Thus, the required penetration grade for a good structure acceptable lto the owner may be determined.

The concentration and amount of emulsion to be applied to the road surface is further controlled by the requirement that the emulsion be absorbed into the road surface without wasteful run-olf. The quantity of emulsion to be employed on the road depends thus also on the permeability of the road. Road permeability, measured as milliliters of water absorbed per minute by the road, may be determined by the test procedure `California 34l-A, issued January 1960, by the Materials and Research Department, Division of Highways, Department of Public Works, State of California. To determine the rate of application of the emulsion to the road in treating either freshly laid or weathered roads, the following modification of the above California 34l-A procedure, known as the grease ring test, may be used.

The above emulsion concentrate, diluted with half its volume of water, is applied to the road within the six-inch diameter grease ring, formed as described in California Test 34l-A. The time to absorb meaured incremental volumes of the diluted emulsion is measured. This is continued until, as in the lCalifornia test, the surface remains wetted after prolonged standing. From this data the volume applied per square yard of the top surface of the road, required to be absorbed in a given time, e.g., l5 minutes, is determined.

In addition to rejuvenating weathered asphaltic roads, it has been found that the treatment also acts as a seal in depth. After penetrating into an asphalt pavement, it combines with and expands the asphalt. Permeability of the pavement to water is reduced. In some instances, where initial shrinkage cracks had developed, the treatment reverses the shrinkage process and closes the cracks. Moreover, when placed between successive layers of asphalt pavement, it provides an excellent bond by promoting a fusing of the the asphalt layers at the interface.

Because of its ability to act as an asphalt replasticizer, as a seal in depth and as a bonding agent, the maltenes emulsion described can be used on all types of asphalt paved surfaces not only in preventive and corrective maintenance but also is construction and reconstruction operations.

In preventive maintenance, the emulsion is applied to a str-ucturally sound asphalt pavement as soon as it begins to show signs of aging or brittleness through the symptoms of dryness, surface pitting, ravelling or shrinkage cracking. Generally, these conditions develop in a period of two to ten years after construction, depending on such factors as mix design, asphalt durability, pavement permeability and climatic conditions. Here the object is to penetrate the asphalt pavement and replasticize the asphalt before deterioration of the pavement due to brittleness has progressed too far.

Pavements that have developed a traic glaze from high density trac and grease drippings sometimes require removal of this seal to facilitate penetration.

In corrective maintenance, the oil emulsion is used in conjunction with other procedures to improve an asphalt pavement which is structurally sound but is extensively pitted or badly cracked. Usually the surface requiring treatment must be scraped or loosened in some convenient way and the loose material discarded or sprayed and recompacted. It may also be desirable to incorporate a new mixture of sand and asphalt in the loosened treated surface, in order to provide a proper balance of aggregate and asphalt.

In reconstruction, the oil emulsion may be used to replasticize existing asphalt paved surfaces prior to a resurfacing operation or as an aid in breaking up and reworking an old, weathered asphalt paving while simultaneously replasticizing the asphalt in the mix. In the latter case, the treatment may be suthciently effective to make the mix reusable again as a surface course.

In new construction the treatment, which is applied after the asphalt paving has been spread and compacted, serves two purposes. The maltenes penetrate the surface and combine with the asphalt to restore the properties lost in the mixing cycle at the hot plant. The maltenes also combine with the asphalt to cause the asphalt to expand and close the pores of the pavement, thereby sealing the pavement to the depth of penetration of the oil.

By far the simplest method of bringing together the maltenes and the aged asphalt is by spraying a predetermined quantity of emulsion on the pavement surface and allowing it to soak in. This procedure is always effective in preventive maintenance, in new construction seals and in priming and tack coating operations. Conventional calibrated asphalt spreader trucks may be used.

It has been found that all newly laid asphalt paving and the majority of weathered asphalt pavements, Whether asphalt concrete, plant mix or road mix, are sufficiently permeable to respond to this simple spray and penetrate approach, provided a seal coat has not previously been applied. The grease ring test described above provides a method of determining the amount of the emulsion to be applied in one operation.

If the pavement has had a so-called asphalt emulsion fog seal, there is usually no diiculty in getting penetration, as this type of seal weathers rapidly and wears off in a short time. However, the fog seal does present a problem calling for special precautions, as the weathered remnants of the fog seal will combine with and hold a certain amount of maltenes at the surface, causing a slippery condition. In such instances, a light sanding is necessary, about 1 to 2 pounds of ne, dry sand per square yard, before trac can be allowed on the pavement. It is preferable, however, that sanding not be done before the emulsion has had at least minutes and preferably 45 minutes to penetrate into the pavement.

The following examples illustrate the use of the emulsions for pavements in various stages of distress requiring treatments ranging from preventive maintenance to cornplete reconstruction.

EXAMPLE l The California Standard Specifications previously described give the quantity of asphalt to be applied to a road structure. Examples taken from the California Standard Specifications will illustrate this.

Thus, at page 143, for asphalt concrete pavement the requirement is:

Course asphalt, percent based on total mix:

Percent Leveling 4-5.5 Base 4-5.5 Surface 4-6 I may add sufficient maltenes to bring the total of asphalt, including the added fraction, based on the sample extracted, up to about the maximum percentage permitted by the specification for the road; thus, 6% for the specifications given above. I may, however, exceed this maximum percentage allowed by such specifications by about 2%, increasing the asphalt content to about 8% instead of 6%, i.e., increase the asphalt content to about 1.2 to about 1.3 times the specication requirement, particularly when determining the desirable asphalt content to be established in reclaiming, in place, a weathered road or asphalt pavement.

Reference may also be had to the manual on Design and Construction of Asphalt Roads and Streets, issued by the Asphalt Institute Pacific Coast Division, page 66, Section H(6e), 1952 edition, for methods of determining the allowable percentage of asphalt to be present in various asphalt structures.

The formula for the percentage by weight of asphalt to be used in the mixture with the aggregate, in producing a fresh asphaltic pavement mix from asphalt and aggregate, is given by the formula:

P=the percentage by weight of asphalt to be used in the mixture with the aggregate;

R=the decimal percentage of rock in the mix;

S=the decimal percentage of sand in ythe mix;

F=the decimal percentage of silt in the mix;

C=circumstantial factor, which normally is l.

In order to determine the amount of maltenes to be added, according to the procedures of this invention, I may proceed in the following manner.

A core taken from the weathered road was treated to extract the asphaltic content of the road, and the extract asphalt determined by the method previously described on pages 31-32 of this specification.

The sieve analysis of the recovered aggregate is performed according to the above Asphalt Institute reference. Due to the fact that the weathered asphalt partakes somewhat of the nature of an oxidized asphalt, I have found that the reclaimed road will tolerate an amount of asphalt up to about 30% in excess of the amount specified according to the above formula, i.e., to a value equal to about P-{-.3P. Knowing the weight of the asphalt in the core as determined above, and the top surface area of the core, the weight of the maltenes in emulsied form to be added per square yard of the surface of the road may be readily calculated.

Since the addition of maltenes is limited by the amount which the road can tolerate and be stable, i.e., form a homogeneous body without exudation of oil as a separate phase, it has been found that a practical application without a preceding core analysis may be made. This procedure depends on the nature of the surface.

The following examples illustrate the methods applied to the above cases. They are given as illustrations of, and not as limitations of, my invention.

EXAMPLE 2 This procedure for relaying completely deteriorated road surfaces consists of three steps:

(l) Breaking up the road to give pieces exposing sucient fractured surfaces for the emulsion to penetrate the aged asphalt, e.g., pieces with no dimension substantially over 4 inches.

(2) Spraying the broken-up pieces with 1A to '1/2 gallon of the emulsion per square yard per inch depth. (In most cases dilution of 4 parts of the above emulsion with 1 part of water before application is recommended to reduce the viscosity of the emulsion and thus to facilitate penetration.)

(3) Regrading and compaction-this operation can be carried out with standard road building equipment. If the asphalt to be reclaimed is from an abandoned pavement, then the product after step (2) can be kept in a stock pile for later use.

The machinery used is (l) a grader equipped with scaritier teeth and a blade; (2) a grader equipped with 29 a set of discs and a blade; and (3) a road oil truck equipped with spreader bar and pump to deliverthe emulsion in required amounts.

The surface is first broken up by means of the scarifier teeth of the grader, then further broken by the discs of the other grader, set to reach down to the base. The blades are used -to turn and mix the broken pieces. After running this equipment back and forth several times to break up the road surface, the surface is leveled by the blade. The spreader truck is then driven over the brokenup surface and a suitable dilution of the emulsion is sprayed on the mix; for example, a 1:1 concentrated emulsion-to-water mix, at the rate of 11/2 gallons per square yard. The emulsion quickly penetrates the brokenup material, coating each individual particle of the mix and depositing a film of the emulsion on the base. The treated mass is then mixed back and forth several times by the blade, and is then graded with a blade. The surface is then compacted by the wheels of the graders. (In some cases a properly graded, reworked surface can be left to automobile and truck traffic for compacting.)

Even in cases where the road shows considerable embrittlement and large cracks, it often suiiices to scarify the road surface slightly, to spread the required amounts of the emulsion onto the surface and let capillary action carry the reclaiming agent into the pavement. If the surface is uneven and badly cracked, it is advisable to till the cracks with an asphalt-sand mix and to cover the whole road with a thin layer of this mix in order to form an even surface.

EXAMPLE 3 Procedure of Example 2 is to be use-d with asphalts which have deteriorated to a stage of embrittlement which needs drastic measures for repairing the damage. Although much more economical and much more effective than other methods of repairing deteriorated asphaltic pavements, this procedure may be considered to be only a salvaging operation. Considerable more economy can be achieved by revitalizing asphalt pavements in a planned preventive maintenance program consisting of regular inspections of roads and corrections of damage due to natural aging at its onset, by application of the emulsion of this invention in the process of this invention.

lPreferably the procedure of Example 3 is started as soon as the road is constructed and should take place not later than when the first stage of lhardening is evidenced by the appearance of hair cracks. At this stage of the aging process, spraying of the surface with small amounts, for example, 0.05 to 0.15 gallon per square yard per inch depth (sometimes followed with a light application of sand), reverses the aging process and gradually restores the asphalt to its original plasticity. It can be expected that such maintenance, started soon after completion of the road and repeated when needed, will prolong the life of flexible pavements far beyond their original life expectancy. This is the type of operation recommended as preventive maintenance.

Many roads are, however, already in existence and in need of maintenance. Some of the existing roads will be in a condition between the two described under Example 2 and Example 3 and will consequently require maintenance measures between the two methods suggested. This is illustrated by Example 4.

EXAMPLE 4 The operation may include scarifying the road surface by means of discs or heater-planers, removing loose dirt, cleaning out larger cracks in the pavement, filling the cracks with repair material (asphalt reclaimed by use of the emulsions described herein, taken from a stock pile, is highly suitable), and spraying the emulsion with a spreader truck onto the surface. The amounts of emulsion to be -used are usually between about 0.1 to about 0.2 gallon per square yard per inch depth of pavement.

30 EXAMPLE 5 The composition of the emulsion described herein has been designed to be usable for all three procedures of Examples 2-4 and with all asphalts. The difference in degree of aging of different asphalts is taken into account in the recommendation of the amounts of the emulsion to be used. For areas large enough to warrant individual consideration, it is suggested that cores be taken from the pavement, the asphalt extracted and analyzed. From this analytical data a special emulsion and application can be devised.

In designing a revitalizing procedure exactly tailored to fit a particular asphalt, one of the principal precautions to observe is to add the right amount of reclaiming agent, in order not to exceed the total amount of asphalt permissible for the particular mix, i.e., to stay within the stability limits prescribed for the pavement. As shown by laboratory tests and field trials, reclaimed pavements can tolerate (as can constructions made with artificially oxidized, i.e., air blown-asphalt) 20% to 30% more asphalt than aggregate-asphalt mixes made with regular steam reduced asphalts.

The precaution not to exceed the permissible amounts of asphalt in the mix is automatically taken care of, in the produce of each of the Examples 2-4, by adding in small increments, observing the workability of the mix after each addition, and stopping when the desired degree of plasticity has been obtained. The following example is an illustration of a specially devised application.

A core taken from a weathered road was extracted with benzol by the method previously described. The recovered extract asphalt was analyzed to determine its composition. The silt from the filter was combined with the aggregate from the extraction thimble, dried, and sieved to determine the grading of the aggregate. The extraction gave the following results:

Percent by weight of core Recovered extract asphalt 4.6 Recovered aggregate 94.

Loss (water and dust) 1.1

Analysis of recovered asphalt:

Percent Asphaltenes (A) 31.3 Nitrogen bases (N) 28.7 First acida-ffins (A1) l0.l Second acidaiiins (A2) 13.1 Paraffins (P) 16.8 N-l-Al/P-l-AZ 1.3

Sieve analysis of recovered aggregate (according to procedure given in Design and Construction of Asphalt Roads and Streets, issued by Asphalt Institute, Pacific Coast Division, 1952 edition, p. 66, Section H (6e)):

Percent Rock portion, retained on 4 mesh screen 68.2 Sand portion, passing 4 mesh and retained on 200 mesh 26.2

Silt portion, passing 200 mesh screen 5.6

The formula for maximum allowable asphalt content given in the above reference is applied as follows:

P=percentage of Iasphalt to be used;

Rzdecimal percentage of rock;

S=decimal percentage of sand;

F=decimal percentage of silt;

C=circumstantial factor, which has been found to be 1.2 to 1.3 for reclaiming of weathered asphalts;

= 12.5 (5.23 6.54% maximum permissible asphalt content.

Images