US3038393A - Pavement and method of making the same - Google Patents

Description

June 12, 1962 H. s. NAGlN ETAL 3,038,393

PAVEMENT AND METHOD OF MAKING THE SAME Filed May 5, 1954 INVENTORS HARRY S. NAGIN DONALD H. RUSSELL I BY M "ml ATTORNEYS United States Patent 3,038,393 PAVEMENT AND METHOD OF MAKENG THE SAME Harry S. Nagin, Merion, Pa., and Donald H. Russell,

Haddonfield, N.J., assignors to Reliance Steel Products Company, McKeesport, Pa, a corporation of Pennsylvania Filed May 5, 1954, Ser. No. 427,880 11 Claims. (Cl. 94-9) This invention relates to the art of paving and is for an improved pavement and method by which a layer of asphalt may be applied and effectively retained on an underlying base of concrete, cobblestones, metal, or the like.

When concrete road surfaces begin to disintegrate, their useful life can be extended substantially by covering the same with a layer of asphalt. However if the asphalt is applied to the road surface without any preparation, it will creep, buckle and break loose. The method commonly used at the present time to try to overcome this is to scarify the concrete by chipping it with air hammers or otherwise mechanically scoring its surface with deep indentations. The asphalt being pressed into these indentations when it is rolled is more effectively retained in place, but the cost of scarifying adds substantially to the cost of resurfacing such a road and does not aid in any way in preserving the road. In other places it is desirable to apply asphalt to brick or cobblestone paving, and here again it is diflicult to adequately retain the asphalt against creepage, buckling and breaking. At other times it may be desirable to apply asphalt over wooden bridge decks or factory platforms or floors, or to metal plates constituting the floors of platforms or factories.

The present invention has for its principal object to provide a relatively cheap and more effective method for keying and holding the asphalt on the surface to be covered.

A further object of our invention is to provide a method of securing and holding the asphalt which is less laborious and more economical than mechanically scarifying the underlying base.

A further object of our invention is to provide an improved road or paved surface having the asphalt keyed to the underlying base in an improved and novel manner.

Our invention may be fully understood in connection with the accompanying drawing which illustrates a section through a roadway constructed in accordance with our invention.

According to the present invention the base surface to be paved, be it concrete, wood or metal, is first preferably thoroughly scrubbed and cleaned, using water and detergent where this appears necessary, and in the case of areas which are greasy, some treatment to cut the grease is employed. Hydrochloric acid for example may be applied to concrete areas which have grease covered areas, or solvents such as chlorinated hydrocarbons may be used to aid in removing the grease. After being cleaned, the surface is allowed to dry, and best results are secured if it becomes entirely dry to the touch before further treatment is continued.

When the surface has become dry we may follow either of two procedures in carrying out our invention. In either case we use a thermosetting resin, preferably an epoxy resin of a syrupy consistency with which we mix one of the usual catalysts employed in the curing of epoxy resins. After the catalyst and resin have been thoroughly mixed, we may, according to one method, mix into it coarse, hard pieces of aggregate, such as coarse crushed rock or very coarse gravel, the rock or gravel preferably not being substantially finer than /2 3,038,393 Patented June 12, 1962 inch in its smallest dimension, and preferably not exceeding 2 inches in its maximum dimension. Within these ranges the pieces may vary as to size, or they can be more or less screened to a uniform size. When the mixture has been made, and while it is still in a quite fluid condition, it is spread over the base surface to be treated and the proportion of gravel or rock used is such that the majority of pieces of rock or gravel. will preferably be out of contact with other pieces and haphazardly spotted or scattered at fairly close intervals over the base surface, the majority of the pieces of rock or gravel being isolated one from another. The resin, as it cures, will tenaciously bind itself to the underlying base, be it concrete, wood or metal, and strongly cement the coarse pieces of gravel or stone to the surface of the road or other surface to be covered.

When the resin has been finally cured, it will adhere to the concrete as firmly or more firmly than the concrete itself is cohered, and the stones or pieces of gravel will be cemented in place so strongly and firmly that a substantial hammer blow will not break or dislodge them.

When the resin has become thus set and cured, asphalt is applied to the base over which the resin with the aggregate has been spread, and the asphalt will be rolled in the usual manner. The numerous scattered large pieces of aggregate projecting above the surface of the base or paving form keys or teeth about which the asphalt is pressed and interlocked, the depth of asphalt being at least as great or greater than the maximum diameter of aggregate, so that the aggregate will not be exposed at the road surface.

By this procedure the asphalt is keyed to the road or surface to which it is applied and the keying action which is secured is much more effective than the scarifying operations presently used. The resin coating which is applied to the base need only be substantially thick enough to form a continuous film, and the film may be A; inch thick or less. As a matter of fact the scattered pieces of coated rock or gravel will adhere and form the necessary keys without any continuous film being formed over the base, but a continuous film is preferred because such film will be resistant to water and will enter into crevices in the road surface and seal and protect it from water and moisture, and particularly water and moisture that may permeate the overlying asphalt layer,

As an alternative procedure the resin of syrupy consistency is first mixed with a catalyst and then spread or sprayed over the surface of the road or other area to be treated to form a continuous thin film, and then the screened aggregate may be scattered or spread sparsely over the resin film. As the gravel falls onto the wet surface film of resin it will be wet with the resin, and as the resin sets, the material so scattered over the surface will be cemented to the surface and firmly bonded in place.

As a modification of this procedure, the aggregate may be separately coated with the resin and catalyst mixture while the base is also coated with such a mixture and then the previously coated stones or other aggregate may be scattered over the previously coated base before the resin has cured.

Still a further procedure is to scatter the aggregate over the base and then apply the liquid resin mix. Also the aggregate may be scattered over the surface, then finely divided material such as furnace slag, sand or emery, of relatively coarse grit may be spread or tossed over the surface, whereby the small grains will fall or travel under irregular pieces of aggregate that may themselves have only a small area of contact with the base. Then when the resin is applied and cured, these smaller grains under the larger pieces will serve to provide additional connection between the aggregate and road surface and provide support-for such pieces against pressure that might otherwise tend to rotate or roll such aggregate and excessively stress the small area of contact that it has with the surface. The fine granular material is sparsely applied in a quantity sulficient only that slight amounts of the granular material may exist around and under the large pieces of aggregate.

The epoxy resin can be used in either cold or hot weather, but its curing time may vary according to the temperature and the curing may be accelerated if the resin-catalyst mixture is applied hot. Also the time required for the resin to cure will depend on the consistency of the resin which is used and the catalyst which is employed. The commercial range of consistency of these resins vary widely and they can be procured with various viscosities from material having a very low viscosity and high fluidity through a range of increasing viscosities to preparations that are of a gummy consistency and even to solids at room temperature. As indicated above, we prefer to use a resin which has a relatively thin syrupy consistency, somewhere between the lowest viscosity resin and the highest. Epoxy resins, as disclosed in our copending application Serial No. 427,874, filed May 5, 1954, are reaction products of epichlor-hydrin and diphenol propane. United States patent to Wiles, No. 2,602,785, dated July 8, 1952, discloses a method of forming such resins of different consistencies. Epoxy resins such as those sold by the Shell Oil Company under the trade name Epon and designated by that company as resin 82 8, 834 and 562 have been found to be quite satisfactory, and also resins commercially available under the trade name Araldite designated AN-102, AN-llS and Chi-502 have been found equally satisfacrtory. A resin of thin syrup-like consistency will spread readily and wet the base to Which it is applied so as to make an intimate bond therewith and because of its wetting properties will also wet the aggregate which it contacts.

The catalyst which is employed is a polyamine and typical catalysts are diethylene triamine, ethylene diamine, dimethyl-aminopropylamine, diethylarnino propylamine, piperidine, and pyridine.

As is well know, the epoxy resins are thermosetting resins and therefore once they have been applied to the roadway and cured, they are unaffected by conditions of heat and cold, and this is a desirable property especially in summer time when the asphalt may become somewhat softened by heat and has the greatest tendency to creep. Since the epoxy resin is unaffected by the heat, the anchoring aggregate does not loosen or soften under these conditions, and the anchorage for the asphalt thus remains secure. These resins have an extraordinarily high adhesion to concrete, wood and metal, and from this standpoint they provide a very secure bonding medium for the lumps or pieces of stone which are provided as keys. The material is unaffected by strong chemicals, resists scrubbing with water, and has a high strength even at low temperatures both in shear and in tension.

Utilizing our invention, a road surface or other area to be paved with asphalt can be easily and economically prepared with a more effective means of anchoring the asphalt than has heretofore been available. Moreover the aggregate forming the keys is embedded in the asphalt forming a more effective anchorage for the asphalt than with previous methods where the base material is scarified or recessed or hollowed out to receive the asphalt. The amount of labor required is substantially less than with the present method of scarifying so that notwithstanding the relatively high cost ofthe resin, it is more economical than the present methods of preparation. It may also be noted that the asphalt will adhere just about as firmly to the resin film as it will to the flat uncoated area of concrete, and more firmly than it will to untreated wood or metal, so that the asphalt is not only well anchored,

but its adhesion may be good or better than the adhesion of asphalt to uncoated surfaces.

Instead of using epoxy resin, we may use other thermosetting resins that will cure without high heat and pressure, as for example resorcinol formaldehyde types of resins or phenol formaldehyde types of resins suitably prepared for curing under these conditions, but the epoxy types have been found preferable for strength, reasonable curing time and adhesion.

In the accompanying drawing a road surface according to our invention is disclosed. In this drawing, 2 is the original road or base, 3 is the layer of epoxy resin adhesively bonding the irregular lumps of aggregate 4 to the base. The asphalt top surface filling in around the aggregate and extending to a level above it, is designated 5.

While we have mentioned certain specific procedures and particular resin compositions, it will be understood that this is by way of illustration and that various modifications and changes may be made within the contemplation of our invention and under the scope of the following claims.

We claim:

1. A pavement comprising a hard, solid pavement supporting base, scattered pieces of relatively large aggregate of the order of about /2" to 2" in size adhesively bonded to the surface of said base by a film of a resinous composition comprising a cured thermosetting resin selected from the class consisting of epoxy resins and phenol-aldehyde resins, said pieces of aggregate being partially embedded in said composition with more than about /1 of the height of said pieces of aggregate projecting above the surface of said film to provide projections by which a layer of asphalt is anchored and keyed to the base, and a layer of asphalt thereon, said aggregate being embedded in the layer of said asphalt to anchor and key the asphalt to the base.

2. A pavement as recited in claim 1 wherein the cured resin comprises the reaction product of an epoxy resin and a curing agent therefor.

3. A pavement as recited in claim 2 wherein said resinous film is continuous and substantially completely covers said base.

4. A pavement comprising a hard, solid pavement supporting base, scattered pieces of relatively large aggregate and pieces of relatively small fine aggregate substantially smaller than said relatively large aggregate adhesively bonded to the surface of said'base by a film of a resinous composition comprising a cured thermosetting resin selected from the class consisting of epoxy resins and phenol-aldehyde resins, said pieces of large aggregate being partially embedded in said composition with a substantial portion of the height of said pieces of large aggregate projecting above the surface of said film to provide projections by which a layer of asphalt is anchored and keyed to the base, at least some of said pieces of small aggregate being positioned under portions of said large pieces of aggregate, and a layer of asphalt thereon, said large aggregate being embedded in the layer of asphalt to anchor and key the layer of asphalt to the base.

5. A pavement as recited in claim 4 wherein the cured resin comprises the reaction product of an epoxy resin and a curing agent therefor and said resinous film is continuous and substantially completely covers said base.

6. A pavement as recited in claim 5 wherein said base comprises concrete.

7. A method of paving comprising adhesively bonding scattered pieces of relatively large aggregate of the order of about /2" to 2" in size to a hard, existing pavement base by a composition comprising a thermosetting resin selected from the class consisting of epoxy resins and phenol-aldehyde resins, and a curing agent for said resin, said pieces of aggregate projecting upwardly from said base with spaces between said pieces of aggregate, said spaces having a depth more than about /1 the height of said pieces of aggregate, said resin reacting with said curing agent to cure said resin, and after said resin has cured, applying a layer of asphalt to said base and aggregate so that the upstanding pieces of aggregate are embedded in the asphalt to anchor and key the asphalt to the base.

8. A method of paving as recited in claim 7 wherein said resin is an epoxy resin.

9. A method of paving as recited in claim 8 wherein said base comprises concrete.

10. A method of paving comprising adhesively bonding scattered pieces of relatively large aggregate and relatively small fine aggregate substantially smaller than said large aggregate to a hard existing pavement base by a composition comprising a thermosetting resin selected from the class consisting of epoxy resins and phenolaldehyde resins, and a curing agent for said resin, said pieces of large aggregate projecting upwardly from said base with spaces between said pieces of large aggregate, said spaces having a depth equal to a substantial portion of the height of said pieces of large aggregate, at least some of said small aggregate being positioned under portions of said large pieces of aggregate, said resin reacting with said curing agent to cure said resin, and after said resin has cured, applying a layer of asphalt to said base and aggregate so that the upstanding pieces of large aggregate are embedded in the asphalt to anchor and key the asphalt to the base.

11. A method of paving as recited in claim 10 wherein said resin is an epoxy resin and wherein said relatively small aggregate and said relatively large aggregate are applied to the base prior to the application thereto of said resinous composition.

References Cited in the file of this patent UNITED STATES PATENTS

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