US1750096A - Method of sttefaging eoads - Google Patents

Description

Patented Mar. 11, 1930 UNITED STATES SAM IE. FINLEY, or

ATLANTA, GEORGIA METHOD or sunraome noADs No Drawing. Application filed April 6,

The invention relates to a methodof surfacing roadways of various standard types with bituminous mixtures, equal in appearance and stability to bituminous concrete, sheet 6 asphalt and the like, preferably in the'form of a relatively thin sheet, which will constitute an effective wearing surface and also bring about an autogenous union between said Wearing surface and the body or foun- 10 dation of the road, themethod involving the premixing of, fine mineral aggregate with a stable bituminous binder containing a rela tively high percentage of volatile solvent or liquefier admixed with said binder, the mineral aggregate being applied'in a relatively thin layer to the surface of the road, that had beenlcoated with asphaltic cement, or upon mineral aggregate that had been previouslytreated with bituminous cement.

The invention is applicable to the resurfacingof old roads of anyknown type and is equally valuable inthe reclaiming of old asphaltic roads such as sheet asphaltand the like, or of penetration macadam, old surface treatments where a relativelyrich bituminous mixture lies upon the immediate surface thereof, or in supplying a wearing surface to newly-constructed roads of various types, such as hydraulic-cement-concrete roads, penetration macadam roads, or roads constructed of brick, gravel, water-bound macadam, sand-clay, shell and the like, and is adaptable to walkways, tennis courts, etc. I t In applying the invention to surfacing all types of roads indicated, it is preferable to remove all loose material from the surface of the road or foundation, and if old foundations of surfaces are badly cracked, such as concrete, sheet asphalt and the like, said openings are preferably first filled or treated with a pure bituminous cement, or if the same be an old road that has been worn by traflic or eroded by the weather, the same is brought up to the proper contour and grade by reworking, if the (road is ofthe type bonded by water, such as macadam and gravel, or by filling up rutsanddep ressions for the purpose of obtaining a reasonably true cross sectionand grade.

'0 ,Whether the aggregate be of relative 1928 Serial No. 268,074.

coarse sizes such as that in the common ractice of penetration macadam or the li e in v new construction, or if it be a surface such as concrete, brick, macadam and the like, an

application is first made in the desired quanl tity of a stable bituminous cement, and the material to constitute the wearing surface of the road is prepared by mixingrelatively fine mineraliaggregate in the form of that which would constitute a well-graded sheet asphalt wearing surface, or in the form of stone chips, pea-gravel, crushed sand, slag or the like, with a stable bituminous cement or binding agency, together with a relatively high percentage of a volatile solvent or liquefier admixed with a bituminous cement in the desired proportions, such as gasoline or an equivalent light distillate, the admixture of 1 the stable and volatile constituents preferably being in the proportions of two to one and the relation of the stable bituminous binder to the aggregate, after volatilization of the liquefier and the replacement thereof by the surface tension coating as hereinafter described, being such that the binder on'setting up will effect a thorough union of all nous mixture would equal 10% by volume of the'fine aggregate, and the stable bituminous cement and the volatile hydrocarbon would 7 be in the proportion of two to one.

The composition comprising the aggregate,

the stable bituminous binder containingvolatile solvent is thoroughly mixed and spread in a uniformly thin layer on the surface of the roadway. Volatilization of the volatile solvent begins immediately, the first tendency, however, when the composition is spread, is forthe volatile matter to work toward the bottom, thereafter beginning its journey upward. At the same time, when the mixture is thus brought into contact with the stable bituminous cement this stable material is drawn upward by capillary attraction and surface tension into the surface layer and replaces in every instance that which is lost by volatilization, so that when the volatile consituent is finally dissipated the applied surface layer contains that quantity of binding medium that will thoroughly and uniformly bond the mineral aggregates together. Therefore, if a stable bituminous cement is mixed with 33 of the volatile solvent and the mineral aggregate mixture contains 10% of such admixture of bituminous material, the loss by volatilization would be 33 which would leave an insufiicient amount to properly bond themineral aggregates together, but as stated, when the dissipation of the volatile matter begins to go upward, it draws from the bottom of the layer the bituminous cement in approximately the same percentage, and a uniform coating to replace that lost by volatilization.

When the invention is applied to the sur facing of a bituminous macadam or penetration road in the course of construction, the coarse aggregate is spread as usual in a uniform layer on the bed site and coated with the usual proportions of bituminous cement necessary to bond the elements of the coarse aggregate, after which the mixture of the fine aggregate with the indicated proportions of bituminous binder and volatile solvent is spread in uniform'layer over the coarse aggregate course, with the result that the fluent mixture in the surfacing course first flows downward and contacts with the binding medium of the coarse aggregate, causing the latter to coalesce with the mixture, after which the admixture of the two binding media is drawn up by capillary attraction and sur face tension into the surface layer, so that, when the volatile constituent is finally dissipated, the applied surface layer contains an adequate quantity of bindingimedium to thoroughly and uniformly bond the elements of the same and also to effect a homogeneous union between the applied surface layer and the subjacent coarse aggregate layer.

In the case of hydraulic cement concrete roads, brick surface roads and similar roads in which the surfaces are relatively tight and non-porous, it is preferable to first apply a coating of stable asphalt, which has been liquefied by heating, and then apply to this thin coating of asphalt or bitumen a layer of the premixed aggregate, stable bituminous binder and volatile liquefier of the latter, whereupon the fluid bituminous binding medium in the premix will flow downward and coalesce with the asphalt coating previously applied to the road surface and, as the volatile solvent in the premix evaporates, a pordrawn up into the body of the mineral aggregate layer .to replace the volatilized constituent and supply any deficit in the stable bituminous binder in the premix.

When the method is applied to the surfacing or resurfacing of asphaltic or bituminous concrete or macadam roads, the liquid bitumen will first flow downward in the applied surface layer, and, upon contact with the asphaltic or bituminous binder in the orig inal road, the volatile constituent of the application will soften or dissolve a portion of such binder and cause the same to coalesce with the mixture, so that both the binder of the original road and the binder of the application will be drawn upward into the surface layer, and when the volatile liquefier has evaporated, the surface layer Willbe thoroughly bonded as to its aggregate elements and said surface layer will be uniformly and effectively cemented to the original road structure to which the application was made.

Under all conditions of application, the efliect of the volatilization of the solvent for the bituminous binder is to draw the latter by capillary attraction and surface tension into the upper portions of the layer of applied mineral aggregate, so that all of the elements of the aggregate will be thoroughly and adequately bonded to constitute an effective wearing surface.

One outstanding advantage of the particular mode of preparing and applying the wearing'surface to old roads or to new roads is the fact that it is possible to employ highly stable asphalts, i. e., 50-60 penetration, which will be rendered quite fluent upon admixture with approximately 35% of gasoline or similar volatile solvent and which will constitute the most effective cementitious bond for the individual elements of the aggregate of the wearing course and also securely bond or weld the wearing course to the surface of the roadway, after the solvent has evaporated.

What I claim is:

1. The method of surfacing roads which in- I clude bituminous cement in their structure, which comprises premixing mineral aggregate with a stable bituminous binder and a volatile solvent for the latter, the binder be ing in quantity to effectively bond the aggrc gate and form a homogeneous matrix therewith and applying the mixture in a substantially uniform layer to the road surface; whereby the binder of the mixture will be augmented by the cement of the road 'struc ture.

2. The method of surfacing roads which include bituminous cement in their structure which comprises premixing fine material aggregate with a stable bituminous binder and a volatile hydrocarbon solvent of the latter the binder being in quantity to effectively bond the aggregate and form a homogeneous matrix therewith, and applying the mixture in a substantially uniform layer to the road surface; whereby the binder of the mixture will be augmented by the cement of the road structure.

3. The method of surfacing roads which include bituminous cement in their structure, which comprises premixing fine mineral ag gregate with approximately ten percent by K0 volume of stable asphalt and a volatile solvent for the latter in approximate proportions of two to one by volume, and applying the mixture in a substantially uniform layer to the road surface.

4. The method of surfacing roads which include bituminous cement in their structure, which comprises admixing mineral aggregate with a fluent binder including a table asphalt and a volatile hydrocarbon solvent of the latter in approximate proportions of two to one the binder being in quantity to effectively bond the aggregate and form a homogeneous matrix therewith, andapplying the mixture in a substantially uniform layer to the road surface; whereby the binder of the mixture will be augmented by the cement of the road structure.

5. The method of surfacing roads which include bituminous cement in their structure,

which comprises premixing fine mineral aggregate with approximately ten percent of a mixture of stable asphalt and gasoline in approximate proportions oftwo to one the binder being in quantity to effectively bond the aggregate and form a homogeneous matrix therewith, and applying the mixture in a substantially uniform layer to the road surface; whereby the binder of the mixture will be augmented by the cement of the road structure.

6. The method of surfacing roads which include bituminous cement in their structure, which comprises applying a coating of stable asphalt to the road, admixing fine mineral aggregate with a liquid hydrocarbon binder including a stable asphalt and a volatile solvent therefor the binder being in quantity toefl'ectively bond the aggregate and form a homogeneous matrix therewith, and applying the mixture in a substantially uniform layer to the precoated road surface.

In testimony whereof I affix my signature.

SAM E. FINLEY.