US1370815A - Pavement and process of making the same - Google Patents

Description

G. A. HENDERSON. PAVEMENT AND PROCESS, or MAKING THE SAME.

APPLICATION FILED JAN-15 9]8- 7 1,370,815. Patented Mar. 8, 1921.

4 SHEETS-SHEET G. A. HENDERSON. PAVEMENT AND PROCESS OF MAKING THE SAME. APPLICATION men jAN. 1s.191a.

G. A. HENDERSON.

PAVEMENT AND PROCESS OF MAKING THE SAME.

APPLICATION FILED JAN. 15, I918.

1,370,81 5. Patented Mar. 8, 1921.

4 SHEETS-SHEET 3 mum- Q in all G. A. HENDERSON.

PAVEMENT AND PROCESS OF MAKING THE SAME.

APPLICATION FILED JAN- l5| I918.

Patented Mar. 8, 1921'.

4 SHEETS-SHEET 4.

UNITED STATES.

PATENT OFFICE.

GEORGE A. HENDERSON, OF ST. ALBANS, WEST VIRGINIA, ASSIGNOR TO THE BITU- CONCRETE COMPANY OF AMERICA, OF CHARLESTON, WEST BATION OF WEST VIRGINIA.

VIRGINIA, A CORPO- PAVEMENT AND PROCESS OF MAKING THE SAME.

Specification of Letters Patent.

Patented Mar. 8, 1321.

Application filed January 15, 1918. Serial No. 212,194.

To all whom it may concern:

Be it known that I, GEORGE A. HENDER- soN, a citizen of the United States, residing at Highland Villa, at St. Albans, in the county of Kanawha and State of West Virginia, have invented certain new and useful mlplrovements in'Pavements and Processes of aking the Same, of which the following is-a specification.

My invention relates to a combination of the two types of pavements characterized and known to the trade as bituminous macadam, having a wearing course of broken stone with some interstitial spaces filled by penetration methods with a bituminous binder, and as bituminous concrete, composed of stone, gravel, sand, shell, slag, or other aggregate, or combinations thereof, and bituminous materials, incorporated together by mixing methods; and relates to substantial departure from the ordinary methods and from the apparatus heretofore used in such construction, in various particulars which will be more fully exemplified and set forth in the subjoined detailed specification.

The invention particularly relates to resurfacing macadam roads to a substantial thickness of mixed and bonded material, the major portion of the mineral aggregate in which is composed of the old road, with which a comparatively small quantity of new material is mixed in cases where traflic has left a sufiicient quantity of metal over an adequate sub-base for the purpose of increased traflic to be attracted by the improved structure, and the object of my invention is the economical correction of conditions in the prior art relating to paving structures, the sanitary removal of dust from the surface of a highway, as well as from its internal structure, to be reincorporated and retained therein suspended in bitumen.

In carrying out my invention a roads surface is broken, then scarified, and, during heating of the surface to a substantial depth, the surface and internal dust is removed and the remaining aggregate, in its loose, ridged, heated and dustless condition, is coated, during turning, with bitumen uniformly distributed, under pressure, suflicient to also cause penetration of the remaining aggregate on the roadway, to which surface is immediately added new material consistmised however, that various changes may be made in the apparatuses by which the same may be operated and the rocess carried out, without departing from t e spirit and scope of the appended claims.

Figure 1 is a view partly in side elevation and partly in vertical section of apparatus adapted for carrying out the invention; Fig. 2 is a cross sectional front end view, and Fig. 3 a cross sectional rear end view thereof. Fig. 4 is a top cross sectional view of the machine and of a roadway under its treatment; Fig. 5 illustrates a pavement in vertical section before reconstruction, in which a is dust,-b is stone and c is earth; Fig. 6, a similar section after it is scarified and the interstitial dust removed, in which a is dust, 6 stone, and c earth; Fig. 7 a similar section after a bituminous compound has been added thereto, inwhich a is dust, 1; stone, 0 earth and d bitumen; Fig. 8 a simllar section of pavement reconstructed in accord with this invention, in which a' represents relatively small sizes of stone coated with bitumen and mixed with bituminized dust, b'- is the bitumen coated stone shown in Fig. 7, cis earth, and a is unremoved dust in the lower section of.the pavement penetrated with bitumen. Fig. 9 1s a cross sectional view, representing the entire width of a highway reconstructed in accord with this invention, in which F is the material shown in Fig. 8, G G shoulders thereto constructed by the ordinary penetration method, or added stone aggregate, and C, C earth.

In instances where the highway is completely reconstructed fourteen feet or more shown in Figs. 1 and 3 constitute two sides of the furnace hereinafter described, the

half feet of metal shoulders shall be added.

V to each side) multipedal or caterpillar .J and front pivot 'andrear axle supports ,s eed traction units are designed to constitute such furnace sides and support the rear of the machine in lieu of its side wheels S, S in Fig. 3.

The entire machine is designed to travel over the surface under reconstruction at a predetermined and automatically xed by moving members operating the machines internal mechanism consistent with its capacity and the area of the pavement under construction. To illustrate, on the basis of a machine whose capacity is 1000 sq. 'yds. of 2"v compressed new material per eight-hour day, (passing out of the drum hereinafter described), which material, representing substantially one-third of the bituminous-concrete surface constructed in the operation, is pressed into said interstices of the remaining two-thirds of material left on the road on the basis of approximately Q" of thickness of such added material, the machine, in constructing a strip of highway seven feet wide by 3428 feet long in eight hours shall travel at the rate of approximately 428 feet per hour, and subject all parts of such surface to the hot blasts hereinafter described for the period of approximately two minutes, the length of the furnace and drum being approximately fifteen feet.

In reconstructing a country road, with main trafiic center seven feet in width, widened to from ten to fourteen feet in wearing surface, width, in the manner hereinafter described; the old surface is not necessarily brought to crown or otherwise treated except to provide adequate side drainage; the added center material, shaped off by penetration method shoulders has been found to be adequate in this regard. Substantial depressions are completely filled with untamped, cold stone preferably of the character of which the old road was constructed; the roadway is not swept, the-dust being handled by the machine which simultaneously burns the combustible material therein as well as that leached to the interstices. Freshly deposited manure and the larger particles of foreign matter that may be present on the road shall be removed, ahead of the machine, manually. A Referring, now, to Flgs. 1 and 2, .I-beam In such inj j constitute the frame work of the machine, properly braced, front supporting roller 1' having a spiked tread the width of which is that of the machine and designed to partially break the old surface of the highway. The sufiicient Weight of the end (l supplied under sufficient air pressure 'with oil from forward auxiliary equipment,

through supply ipe d, are designed to throw downward y and backwardly a blast of flame (w w) equivalent to approximately 1500 cu. ft. per minute capacity, later augmented by (a) like burners of approximately 1000 cu. capacit per minute, which may be faced downwardly and forward, and connected with the supply pipe d extending through the longitudinal center of the furnace, and (b) the sheet blast of hot air from drum Z hereinafter referred to.

The furnace consists of a bottom, to-wit: the roads surface; the furnace top consists of the bottom of the bitumen tank is; its sides consists of said multipedal units or temporary curbing anchored to the pavement by spikes f designed to be removed after compression of the completed pavement, and relaid ahead of the machine, such sides havingoverlapping members e 6 with lateral springs e, which overlapping members 0 e and curb f are designed to carry no part of the weight of the machine, or to guide it, but are designed to eliminate lateral suction of cold'air to the furnace, and to retain the elevated surface caused by scarifying.

The dust and fine particles, in quantity exceeding fifteen-per cent. of the aggregate, ranging from those that willpass a 80-holes to the linear inch screen to thosesubstantially smaller than those that pass a screen of 200 mesh to the linear inch, are loosened by (a) the forward roller spikes, (b) the scarifiers and (0) the aforesaid hot blasts, as well as b suction through fans C C C and C Fig. 2% revolved by belt and pulley connections C shown in detail in Jig. 3. Such dust and fines are thereby lifted from the surface of the highway, through screens (shown in 4) at the mouth" of fines f 7'' (shown in g. 1) penetrating bitumen tank In and passed through continuation of ,flues f to-wit: flues f and f, then through fan C, ina cloud to and within mixing drum 1 anits ends) with hot bitumen, which. from an auxiliary supply tank, is, in said tank k further heated after reaching it, throu h intake p (preferably asbestos covere under pressure, which heat in tank is is supplied by the furnace at its bottom and through flues f aforesaid. An approved thermometer, anchored in sight of the operator, is set within the metal of tank is and the temperature of the bitumen therein is regulated by adjusting the supply to fuel oil burners d aforesaid. The bitumen in tank It is designed to be constantly agitated by suction through pump 0 with indicator 0' through intake pipe n and outlet pipe 723, which is designed to supply the flow of bitumen to and within the forward end of drum Z, through cook a and indicator n in predetermined quantity under control of an operator there seated,

which quantity is fixed consistent with the.

uantity of clean, cold stone which passes m hopper Q through gate Q (Fig. 1), which gate is automatically revolved by cogged wheels M (Fig. 1) anchored to main motor-driven shaft m, at a speed fixed consistent with the capacity of drum Z, as determined by its size and the speed at which material therein may be manipulated by agitators Z set at angles to form a perfect screw therein, to agitate and 'push the material from the forward to its rear end, while mixing, and out at gate Z, automatically revolved by connection at the rear end of main shaft m with cogs m Bitumen agitating pi e n extends to and within the bitumen tan k near its forward end and on the reverse side of drum Z from its intake n, and interposed between the pump 0 and mouth is and operated cock N and con-- nections for withdrawing'bitumen for said prescribed purposes.

The hot bitumen surrounding drum Z is designed to heat drum Z externally, and to thereby heat its contents in addition to the heat thereto applied directly internally through flues g and f aforesaid, for the purpose of su jecting the mixture therein to sustained heat suflicient in duration and temperature, consistent with the capacity of the machine to not only, during agitation and mixing, coat the clean stone screenings with hot bitumen, but to evaporate in the form of steam, any moisture contained in such stone, to be removed from drum Z as hereinafter described.

In this connection be it remembered that moisture becomes steam at a temperature of n 212 degrees Fahr., and at that temperature is exceeding 1000 times its volume as water; that in ordinary paving mixtures bitumen is deposited on preheated stone at a temperature of from 300 to 350 degrees F ahr. and that in this process, as in the prior art, it is designed that the mixture shall be deposited on to the road at an average temperature of 250 degrees Fahr. I, accordingly, have discovered that by entrapping a limited moisture content in cold stone surrounded by hot bitumen such moisthe aggregate during elimination of themoisture content. I have discovered that the moisture, acting as a carrying agent of the bitumen, during ebullition thereof, not only coats the particles with the carried bitumen, during evolution of the moisture into steam, but that the aggregate is thoroughly dried and uniformly coated without danger of burning it or the bitumen, especially when this is done in a drum, the heat surrounding and within which is so perfectly regulatable as by the means herein disclosed.

Before the mass has been agitated by the forwarding blades or agitators Z, anchored to driven shaft M revolved by motor connection at the bearing M at front of the machine, to the extent that such mass has gone midway between the front and rear of drum Z, each particle of such dustless aggregate is thoroughly dried and uniformly coated with bitumen in the absence of dust. Without the circumferential area of the revolving agitators, and alternating dodge fashion about the top of the rear half of drum Z, bitumen atomizing nozzles n spray in the drum a predetermined quantity of bitumen from supply pipe n passing through the hot bitumen in tank is from the auxiliary supply pumped thereto through cock d and indicator d under control of the operator.

Detritus and extraneous matter being removed by destructive distillation in the manner described, the remaining dust from the interstitial spaces and surface of the loosened stone on the road is hot before it reaches the inside of drum Z at its rear end in hot air suspension, and in such suspension bafiied in said drum by plates practically anchored therein for the purpose; such impalpable dust and small particles passing the 80-mesh to the linear inch screen at the mouths to flues f shown in Fig. 4, is, in said drum entrapped by the atomized bitumen sprayed thereon in such hot air suspension, the air thereby freed from the dust, being then sucked, with steam and fumes from the heating mixture in said drum, through the front end thereof by two powerful suction fans C C, shown in Fig. 2, operated by belt and pulley connections operating rear suction fans shown in Figs. 2 and 3.

The steam laden hot air may then be exhausted into thefree air and discarded, or, at the front of the machine as shown in the drawings, this hot air may converge intoa sheet blower C C C G, faced downwardly and backwardly, thereby creating a circular current of air in sheet form mixed with the flame blasts, hereinabove described, on to the surface of the highway, back, up and then forward and down again during the machines forward movement.

In instances where one strip is designed to be laid in the center of the highway, this sheet blower may have attached to its either side, laterally, an oflF-setblower, designed to be extended adjustably forward of the machine, for the purpose of blowing from the surface to the sides, of the reconstructed avement, all dust to and within the vacuum mfluence of the furnace, in order that such sides surface may be dustless for the purpose of receiving bitumen designed to penetrate it at the rear and to the sides of the machine, and of thereconstructed pavement,

' through laterally adjustable nozzles, connected with the pressure distributer of hot bitumen, which will now be described.

On to the loosened, scarified, dustless and heated stone aggregate of sizes larger than 80 to the inch mesh, remaining on the roads surface, illustrated in Fig. 6 hot bitumen from forward auxiliary bitumen heater, passes through cock g and indicator 9 in predetermined quantity under control 'ofthe operator, and through su ply pipe 9 extending within and backwar y through the fire box or furnace to penetration and spraying nozzles g at the rear of the machine, where, under pressure from the supply tank forward, this bitumen penetrates the surface of such road material in its heated, dust cleared loose condition, to an extent substantially greater than is possible by methods known to the prior art. The nozzles g are preferably set dodge fashion oncross pipe 9 (Figs. 2-3) extending the width of the surface under treatment; and, between such nozzles turning tines 6 shown in Fig. 1, harrow and again turn the stone during the bitumens contact therewith, to further facilitate coating of all sizes uniformly.

At this point it is notable that the new clean stone screenings that go into the drum I through hopper Q, are coated with bitumen without interference of any dust mixed with them and that the interstices are filled with particles ranging from 80 mesh size to those substantially finer than 200 mesh size,

(ground to such impalpability by previous traflic on the road and from time to time leached therein) which dust is before reaching the drum preheated in the flame and ing agency, (such as dust in its interstices,

and the chilling influence of cold stone) it being designed that the interstitial spaces between such road stone shall be filled by compression of the mixture from the drum, added thereto while such road stone is in an uncompressed condition, and the mass then pressed into shape.

.It is notable at this point that three different kinds of bitumen may be used in the process, although I do not limit myself to the following advantages of this practice, to-wit: (a) the filler stone screenings may be coated with a hard bituminous cement mixed with a softer ingredient colloidally interposedthrough stiffening dust to act as a filler between such filler-stone screenings in the interstitial spaces of the largerfstone precoated with a different bituminous compound, such operation being economically advantageous in reducing costs of various bitumens, more practically and efficiently usable for the designed purposes than the use of a single ingredient for different purposes.

As the material from drum Z emerges in a continuous flow onto the heated and bituminized road surface in its loose, ridged, condition, it is immediately raked by hand to a depth notexceeding one inch in thickness over the bituminized stone on the road, steam roller compression being relied upon to (a) compress and incorporate the smaller aggregate mixture within the interstices ofthe larger stone on the surface, and (b) to compact such scarified stone into a mass su erior in density to any structure of which have knowledge.

Upon removal of the temporary curbs the completed strip ,may be painted at its proper edges, with bitumen, and other strips added, or shoulders constructed, as shown in Fig. 9 of the drawings.

I claim:

1. The process of treating a worn highway, in a continuous operation, consisting 'in breaking, then scarifying its structure and loosening the bond between the aggregate; then applying thereto hot air and flame blasts under pressure to remove the relatively small particles and dust from the giterstitial spaces of the scarified, material,

tillation removing extraneous matter from simultaneously heating, while turning, the; same, and sucklng, in an suspens on, the

the old structure; then by pressure distribu= ters causing a bituminous compound to penetrate the scarified dustless heated stone remaining in the structure to a substantial depth thereof during turning of said stone, at the same time preparing additional material consisting in clean stone screenings containing atmospherically absorbed moisture, which screenings are then treated by mixing and coating them with preheated bitumen in predetermined proportions of each; then during suction and agitation of the mass, subjectlng the same to sustained heatsuflicient to remove all moisture from and to heat the particles; then mixing the coated stone, while hot, with the small particles and dust removed from the roads surface after coating such dust with atomized bitumen in said drum, and agitating the same therein under sustained heat sufficient in duration and temperature to bring the temperature of the mass'to approximately 250 deg. Fahr; then depositing the same, in quantity merely suflicient to fill the voids between the larger particles when compressed, onto said previously prepared surface'while the latter is hot, then raking and compressing the same into shape, substantially as described.

2. The process of making a pavement consisting in heating a roads surface and removin the dust therefrom by suction thereof to a drum in which it is incorporated within new aggregate after being coated with atomized bitumen therein and then mixed with stone of larger sizes coated in the absence of dust with hot bitumen under sustained heat suflicient to raise the temperature of the mass to approximately 250 degrees Fahn, then depositing the mass onto the heated surface, after sprav ing such surface with hot bitumen, and ra ing and compressing the same into shape.

3. The method of treating a worn surface of mineral matter, consisting in breaking it, then scarifying it, then creating a circular draft of hot air thereover by applying thereto flame under pressure, sucking such flame and hot air through flues into a drum above the surface under treatment by means of fans operated by the mechanism of the self-propelled machine treating such surface, there being provided a plurality of such flames, fiues and fans, which latter also conduct such hot air from the drum back to the roads surface and within the influence of said suction. during movement of the machine over the surface, thereby creating a sheet of flame and hot air of which the plurality of flames form a part; simultaneously heating the surface while removing therefrom mineral matter of sizes smaller than those that pass a screen containing 80 mesh to the linear inch;

eiitrapping the latter in atomized bitumen in the drum and mixing the same with precoated stone under sustained heat sufficient to raise the temperature of the mass to approximately 250 degrees Fahn, and to drive off all moisture therefrom; then depositing the same onto said dustless, heated stone on the road, pre-penetrated by heated bitumen, and pressing the same to substantial density, substantially as described.

4. The method of heating a bituminous mixture for road'paving purposes, consisting in first mixing cold'aggregate with preheated bitumen; then mixing preheated impalpable dust with preheated bitumen, and mixing the ingredients together in a drum heated externally by hot bitumen surrounding it, and the coated mixture directly under sustained heat from the supply thereof that heats the bitumen surrounding the drum; then agitating the mass under such sustained heat until it reaches a uniform temperature of approximately 250 deg. F ahr.

5. The process of forming a paving structure in which the major portion of the aggregate is that of a worn structure of which 1t forms a part, consisting in first scarifyin the latters worn surface to a substantia depth thereof, then directing, in a closure, hot air and flame under pressure thereagainst; then harrowing the surface, and then blowing a plurality of flames from the rear of the machine forward of such surface in said closure durin movement of the machine over such sur ace; then sucking the loosened and heated dust from the surface and interstitial spaces of such structure to and within a preheated drum, and mixing the same with preheated bitumen-coated mineral particles; then forcing'into said surface a predetermined quantity of hot bitumen; then depositing the mixed material thereon, and compressing-the same into shape, substantially as described.

6. The method of treatin a wearing surface of a worn roadway by eating the same with a blast of flames and hot air, simulta-.

neously removin by vacuum suction, the

dust from its sur ace and interstices between its aggregate, and then forcing hot bitumen into suchinterstices by power distribution of said bitumen, entrap ing the dust'in a drum therefor provided: and mixing the same with preheated bitumen, and then mix- .ing the mass with bitumen-coated particles of relatively small size com ared with those of the old surface on whic they are to be spread; then s reading the same onto said surface while t e latter is hot and then compressing the same into shape. I

7 A new paving structure comprising relatively large sizes of stone coated in the absence of dust with bitumen and then bound with a mixture of mineral particles coated with bitumen ofdifierent consistency, in the absence of dust, mixed with bitumen-coated dust acting as a filler colloidally interposed inall interstitial spaces between the coated particles, and compressed into shape.

8. The process of producing a filler for pavement aggregates consisting in mixing preheated impalpable dust in agitated air suspension with mineral matter and preheated bitumen in a drum while dehydrating the aggregate under the influence of suction and sustained heat during agitation ofthe mass, substantially as described.

9. The rocess of producing a bituminized stone an dust aggregate for paving purposes consisting in mixm moist stone particles of relatively small sizes in the absence of dust with a hard bituminous compound which has been reduced to a temporary liquid; then subjecting the mixture to sustained heat during agitation of the mass in an'open ended vat, to convert the moisture in the stone into steam and to impregnate the stone with the bitumen during elimination of the steam from the vat by suction; simultaneously spraying impalpable dust in air and steam suspension in said vat with atomized bitumen of relatively low penetration and then agitating all of the ingredients together within said vat; then removing the same from the vat and spreading the same a over, and then compressing the same within,

interstices between loosened stone of relatively large sizes reheated and bituminized in the absence of ust, while all of the ingredients are hot.

10. The process of making a pavement consisting in scarifying, heating, and removing impalpable dust from the surface and interstices of, stone constituting macadam paving structures; then coating the aggregate thereof in situ with a heated bituminous compound; then spreading thereover a matix consisting of approximately thirty three per cent. by volume of the completed structure, composed of bituminized stone screenings containing in excess of fifteen per cent. of impalpable dust precoated with bitumen, and then pressing the matrix down and within the o n interstices of the macadam structure an consolidating the same by rolling, while all of the ingredients are hot.

n testimonyl whereof I have afiixed my si ature in t e presence of two witnesses this fourteenth day of January, 1918.

GEORGE A. HENDERSON.

Witnesses:

F. L. Amonn, R. C. Swear.

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