US2395996A - Production of a road joint sealing composition - Google Patents

Description

Patented Mar. 5, 1946 was ii I PRODUCTION orsnoanrom'r same 1 t COMPOSITION 1 John '1'. 'Doyle, deceased, late of Anne Arumilel County, Md.; by Mary Doyle, administratrix,

j Baltimore, Md.

No Drawing. Application May 1942, a "Serial No. 444,935

icamw -The invention relates to the construction of" concrete and similar pavements which in order. to prevent ,or reduce cracking due to'expansion and contraction with changes-oftemperature are cast inisections which-are spaced incorrespond- Y ence with the degreeof contraction and expansion' expected. These spaces or;joints between the sections are bridged at a level below the road surface by load transfer members cast in the concrete and are usualiyfllled below the surface l0 with a precast asphaltic or other resilient filler which :is placed in position before pouring the V concrete. The joints'may extendlongitudinally of the roadway as well as transversely,

An extremely important consideration is theeir- .15,

clusion of moisture the entrance of which into the joints and through the joints into the subgrade causes disruption due to alternate freezing and thawing, hencethe necessity for 'p the moisture proof seal, which is the subject oftheinvention.

In the process of construction the precast filler plates or such filler asmay. be empioyed are set on the iinesiof the joints, each inupright position, with itstopedge below-the road. surface.

This leaves. a rabbet or groove which in cross sec- .ticn is customarily about. three quarters of flan inch b three quarters of aninch orthereabouts; overlying the filler-at the top oi-the joint. This a b t groove or r b at is subject to can motion and 39 of these Joint sealing composition's also lack the expansion transversely of its'iength as the .concrete sections or slabs between which it islocated expand and contract. When the pavement is set these grooves :or

rabbets arefliied with a-sealing compound the 3x5 mainpurpos'e of which is to prevent the entrance or moisture into the joints and through the joints intothe subgrade. A" purpose is also of importance istoiill the joints substantially flush with the roadlsurface and thusbridgetheioints to preventing the-bumping of the tires in passing he on er e cee it to i m h I. The problempresented is diiierent i'rom that involved in the sealing of road cracks, and the compositionssuitable for the latter purpose are not suitable 1'0! use inthejsealin ofthefjoints and likewise the present composit n in the, prei'erred Iorm s ibt'sui e to t e se li g" 1 f l d cracks as iii-sets or partiailyfsets sopromptly that itv cannot be satisfactorilyintroduced into openings 0! the width which such cracks normally In the mid-temperate zonc to which the bulk oithe area of the United States proper may ation. of F. being close to the average;

A satisfactory road sealing compound must be capable of low cost production, and easy of ap-' plication and should meet thesetemperature con ditions and continue over a long period to be e'f v fective inthejexclusion ofwater and in the bridging of. thegroovein such ainanner as 'to substantially eliminate bumping of the tires in cross ing the joints. Various bituminous compounds and mixtures of rubber, asphalt, tar and other piastiosubstances have been employed ,with notable absence of satisfactory. results. So far as can be ascertained nosatisfactory composition for this purpose. which can be produced at a figure commensurate with a reasonablecost of construction has yet been produced or offered to the builders of, concrete and similar pavements.

i The difliculties encountered include primarily the tendency of the sealingcornpo sition to harden and crack in cold weather when the concrete sections or slabs contract andgthe grooves or rabbets expandfand these cracks form leaks which admit water tofthe'ioints and to the 'subgrade. Afurther difliculty is the tendency of the sealing material to liquefy at the higher road temperatures so that it escapes from the Joints bothby' leakage andby distribution over theroad. surface due to partial adhesion to vehicletires. .The majority escape from the joint by leakage and adhesion.

to the tires of passing vehicles. There is' also a tendency of the prior compositions due to alternate heating and cooiing't'o form hard protuberances which i cause highly objectionable bumping of the tires. 6 Y c .The object of the present invention isthe production and appl cation .of a concrete road joint sealing composition whereby .the difliculties above recited and other diflicultieswhich occur .in'the. manufacture and use oithe previously known compositions for this purpose are overcome;

said to bciongg'there is an an iuai variatioiijcr c i Th compositionhas been thoroughlytested prevent escape from the joint and to prevent loss to meet the conditions encountered having been mentioned.

In the practice of the process whereby the desired result has been attained the materials in suitable proportion, for example 70 parts asphalt to 30 parts oil thus mixed are blown with air to a softening point designated as approximately 135 F., a reasonable degree of variation above and below this point being regarded as feasible by smearing on the pavement surface and on the tires of passing vehicles. It is also of importance that this composition affords satisfactory support;

for the tires in passing the joints and does not form protuberances which would cause bumping of the tires, nor does it when properly applied.v become separated from the sides or side walls.

of the grooves, particularly in cold weather, forming cracks which admit water. It also has satisfactory sealing properties at medium, temperatures. V j

In the practice of the invention. in' what is regarded as the preferred form, a reasonable degree of variation and substitution being contemplated, the disclosure serving mainly as an example .of. the successful practice of the invention, the sealing composition is manufactured by blending a material having the properties and composition of steam refined asphalt made from Texas crude or substantially such properties, the same being of approximately 50-60 penetration by the standard penetration test which is understood to mean 50 to 60 one hundredths of a centimeter penetration by a standard test needle under 100 grams pressure applied for a period of five seconds at a temperature of 77 F. A blend which has been successful in the practice of the invention comprises 70% asphalt of the quality above described and by volume of an intermediate or flux oil.

The above description is intended to define an asphaltof high ductile qualities containing little or no paraffin and the minimum of sulphur, both 0% which constituents are regarded as undesira le.

Steam refining is mentioned as giving thedesired result, the possibility of obtaining similar conditions and results and an asphalt of similar qualities by other. methods of refining being recognized, the method of producingthis constituent not being a feature of the invention.

The proportions stated and the quality of the thinning or intermediate oil are also subject to such variation as does not forfeit the essential properties of the resulting composition. The intermediate or flux oil used is preferably free or substantially free of sulphur and paraffin.

An intermediate or flux oil which has proved satisfactory for this purpose may beidentified as follows according to generally recognized standard tests.

Anfgriniszn Petroleum Institute hydrometer 60,

Flash point, C. O. 0. (Cleveland open cup), 480 F.

Furol viscosity, 210 F. 45 seconds.

Float test, 150 F. l6-seconds.

and a variation from 130' F. to 140 F. having been ascertained as not interfering with the usefulresult attained. The temperature of the softening point or melting point of the blend is raised by blowing asdescr'ibed, and the ductility at high temperatures is reduced. Mixing as described gives anincreased ductility and penetration at .low temperature which is retained to a satisfacoil which is found to. besatisfactory for this purpose, the possibility of variation and substitution tory degree after blowing. The properties of the combined, materials are thus determined by mixing and blowing, the result being a satisfactory joint sealing-compound. The term softening point thus employedhas reference to a standard test prescribed by the American Society for the Testing of Materials and'thus identified. Blowing-is understood to effect partial oxidation. A blowing temperature of 485 F.;has been found satisfactory. Compensating variations of time, air supply and temperature may be practiced.

The resulting material when used as a concrete road jointsealing compound conforms to the requirements above recited. This composition may be characterized and identified according to the practice inselecting'and determining petroleum and similar plastics as follows:

Melting point (ring and ball test), approximately 135 F. v

Penetration by standard test 32 F., 200 grams pressure standard test needle duration 60 seconds, minimum 20, approximately normal variation 20 to 30 (unit of penetration being ,6 centimeter) d f Penetration, 77 F.. 100 grams pressure standard test needle} duration 5 seconds, approximately 50 'to' 60 units of penetration.

Penetration, 115 F., 50' grams pressure, 5 seconds maximum, approximately 1'75 units of penetration by standard test needle. Y

' Ductility 7'1 F; stretching at rate of 5 centimeters'per minute,"approxiinate stretch 80 to without cracking;

Ductility, 32 F. stretch at rate of 0.25 centimeter per minute without cracking approximately 4.

Flash point, approximately 500 F. The ductilities referred to are determined by and stated in terms of test B 113-39, American Society for Testing Materials.

Solubility in carbon disulphide, 99% minimum. The foregoing specification identifies the prodnot of the invention in the preferred form from which some relaxation of the requirements or a degree of variation may be permitted. The asphaltic composition of the invention is regarded as unique in the attainment of this standard particularly as .to excessive ductility and penetration at low temperatures and a relatively low maximum penetration at high temperatures as stated, which constitute a notable accomplishment in a composition for the sealing of joints of. concrete pavements. The other properties stated are given mainly for the purpose of describing the composition in what is at present regarded as the preferred form. j

In sealing the joints of concrete roads in accordance with the preferred practice of the invention the sides or side walls of the groove or rabbet at the top of the joint are preferably first coated with an asphaltic paint following which the grooves or rabbets are filled with the joint sealing composition of the invention, for which purpose the sealing composition is liquefied by heating, the temperature being preferably from 325 to 340 F., 350 being regarded as the maximum temperature to which it can be heated Without probability of deterioration. Other priming fluids may be employed.

This sealing composition is of an asphaltio nature having the properties above identified and imparted to it by the treatment, above defined.

A satisfactory material for priming or coating the walls of the grooves or rabbets to improve the adhesion of the composition may be made by combining a liquid petroleum product substantially of the nature of naphtha or the equivalent or other suitable thinning agent with a 50-60 steam refined asphalt or asphaltic composition of the properties previously defined under this heading, the manner and source of production being immaterial.

This mixture or paint may consist of 70% naphtha or the equivalent to 30% asphalt which is preferably of the quality used in the sealing composition the proportions and constituents being subject to some variation. Other tion being specific and in detail in order that the manner of practicing, applying and using the invention may be fully understood. However, the

composition and the method described are subject to variation in the light of a full knowledge of the nature of the materials and problems involved and the specific terms are used in a descriptive rather than a limiting sense, the scope of the invention being defined in the claim.

What is claimed as new and desired to be secured by Letters Patent'is:

The method of making a sealing composition for concrete road joints, which consists of blending approximately 70% asphalt, the same having a penetration of -60 at 77 F., the said asphalt being combined with 30% by volume of an intermediate oil containing practically no parafiln, and.

practically no sulphur, the said oil having a flash point of approximately, 480 F., a Furol viscosity of approximately, 45 seconds at 210 F., and a float test at 150 F. of approximately 16 seconds,

thereafter blowing with air at a temperature of approximately 485 F. for a period suflicient such that the resulting material will have a softening point by the ring and ball test of approximately, 135 F. penetration at 32 F., approximately, 20 to 30, under a thrust of 200 grams for seconds, penetration at 77 F., approximately 50-60, under a thrust of grams for 5 seconds, and a penetration at F., of approximately 175, under a thrust of 50 grams for 5 seconds, a ductility at 77 F., of approximately 80 to 100, a ductility at 32 F., approximately 4, and flash point of approximately 500 F.

' MARY H. DOYLE, Administratria: of the Estate of John T. Doyle,

Deceased.