US1192178A - Method of treating roadways. - Google Patents

Description

S. E. FINLEY. METHOD 0F TREATING ROADWAYS. APPUCATION FILED r.15.1915.

1 ,1 92.17 8. Patented J uly 25, 1916.

jane/n @m ff M SAM EVERETT FINLEY, OF ATLANTA, GEORGIA.

METHGD OF TREATING ROADWAYS.

Specification of Letters Patent.

lat exited July 25, 191 6.

Application led February 15, 1915. Serial No. 8,370.

invented certain new and useful improvements in Methods ot' Treatingv lioatlvvays;

.and l do herelrv declare the following to be a full. clear. and exact description otl the invention. such as will enable others .skilled in the. art to which it appertainsv to malte and use the same.

'This invent-ion relates to the surface treatment of roadwaysT and has-for its object to provide the novel method ol' treating roadwavfs. hereinafter described.

-lt has been found in practice that when a roadwayv is treated with heaviP bituminous.A products. for the purpose of preservingr the road' surface and render-iner the same wearresisting. thel bituminous products cannot be inade to bond or unile with the particles ot" the. roadway, as there is always a sufficient amount of dust and loose particles adhering t0 the stone to actas a separator between the stone proper and the heavyv bitumen. This is true, regardless of how carefully the Stone,

may be crushed or graded. This condition i not only exists in "pcm-tration macadam7 surface a portion of sand and cement which will probably7 have sutlicient eementing values to hold them together, but this portion of the. sand so brought to the, surface 1s .not as rich with cement as the lower portion i of the roadway, so that a thin sheet or scalo at the road surface results. which is susceptible to crackingr or separating from the harder and more lirinly united base portion. No matter how carefully this` surface may be swept or cleaned prior to the application of a heav)v bitumen. it hasl been found that a Lmrd union cannot be obtained, as a thin film of dust or foreign matter will always remain to act as a separator between the heavy liquid bitumen and thel road surface. This is also true of practically all types of roadways or street surfaces, includingr roads eolistructed of gravel` water-bound macadam and the like. A lighter bitmnen. however, will penetrate the abrive-mentioned film of dust, but a. light bitumen does not possess the.

necessary preservinpr and tement-ing values.

as it conta-ins a high percentage of volatile matter and only a low percentage of cementA ing value. rlhis light bitumen has'aslits greatest asset, the ahilit \j to suppress dust, but; is of little value in preserving the roadway and renderinglhesame wear-resisting. In fact. it has been found that it often happens that considerable disintegration takes place in the portion of the roadwa)Y treated vwith light bituminous products, t'or thel rear# son that the light oils-\'olat'ili'/.e and leave the. treated portion of the roadway in the form of a coating in which the natural bonding; or cementing values-'of the material are destroyed.

The present inventieni contemplates the use of both the heav v and light bitiuniuous products in such a way as to combine their advantageous qualities` and to dispense with the above-named objectionable effects involred in the. individual use oteach. After a great deal of experiment-uw. it has been found that the lighter materials may be utilized to great advantage when corructiy used in combination with the heavieuiuaterials. and a much better road surface produced than can be obtained by the imlividual use of either of the products. The present invent-ion. therefore, contemplates the treatv ment of the roadway whether the same be of concrete` bituminous macadam. sheet .as phalt. stone, gravel. or othe.` constriaftion, with a lighter grade of bitumen which penetrates the roadway and is not prevented from doing;f so by the existence-ot' dust or foreign matter. At a suitable time after the treatment of the roadwayv with the. lighter bitumen, a heavy bitumen is applied. which firmly unites with the lighter bitumen. and is in this wa)v bonded or cemented with the particles of the roadway. The lighter bit-ie men` therefore. serves as a priming' coat which permits theI use of the heavier bituminous products having wear-resistinpT and other properties notI possessed'by the lighter bituminous products. This priming coat ot li gliter bituminous products, therefore., serves theY sa me purpose as the primingcoat in painting wood or the like., where itl is necessary to apply a. priming coat of thin paint before the wood or other surface treated will re-tv deep into the roadway, and it is retained there by the heavier surface bitumen, which has the following beneficiallaction upon the roadway. The lighter bitumen contains a 5 great deal of volatile matter, but the heavier bituminous coating which has a low per-`v centage of volatile matter serves as a seal, and prevents the escape of the volatile matteis ofthe underlying coatingV of light bituminous matter. As the volatile matters in the lighter bitumen cannot escape, the tendency is for them to penetrate farther and farther into the roadway, and in so Y doing, a chemical action results imparting a. new life to the roadway, and a higher cementing value to the priming coat than it originally possessed. The. disintegrating action caused by the volatilization of the lighter bitumen is,'therefore, prevented, as

the heavier coating prevents escape of the volatile matter. The result is that a hard and elastic road surface is produced which 4has-been found in practice. to be superior to all types of roadways treated by similar 25, methods. If a portion of the volatile matter so confined beneath the heavy bitumious 'coating works upward instead of downward into the roadway, it'will be absorbed by'thefinishing coat of heavy bitumen and 3o act thereupon in a manner similar to what is commonly termed a eut-back, that is tov say, it will make the heavy bitumen more of a. liquid, and this chemical action will result in carrying the heavie'ror finishing T coat farther into the road surface, so that cementive value may be utilized below fthe original` road surface. This action takes place so slowly that practically none of the volatile oils of the primingcoat are lost,

4o-whereas, if the lighter bitumen is used by itself Without the heavier finishing coat, it loses over half of its lighter constituents by volatilization within sixty to ninety days. In carrying out the method, it has been found desirable for the best results to firstl sweep the road surface as free as possible from all loose material, and then apply `the lighter bitumen 'by any 'suitable means, the quantity applied dependingupon the ab- 50 'sorption qualities of the roadway. The

quantity applied should be limited to the amount that the road surface is capable of absorbing., In some instances, it may be desirable to then apply a thin layer of sand,

stone screenings, or sweepings from the road or street surface, and open the roadway to traffic and exposure to the elements. ,T he heavier coating of bituminous material may then .be applied to the road surface, butv preferably the application of the heavier' bitumen is made just after the application of,the'priming coat of lighter bitumen. The second coat of heavier bituminous material may, if desired. be covered with a layer of either sand, fine gravel, or crushed stone.

The lighter bitumen not only` serves to penetrate into the body ot' the roadway, and thereby act as a priming coat. forthehean'ier bitumen, but also produces other beneficial results. due to the fact that itsl volatile matters are confined within the roadway by the 'heavier bituminous finishing coat. The. heavier bituminous coating which would not be bonded and-firmly united with the roadway., if it were not for the relatively light priming coat, produces Athe elastic wear-resisting .sm-face, as the. heavier bituminous products possess the cementing and ucar-resisting qualities which the lighter products do not possess, and which 5 it is essential that the top dressing should possess. 'lfhere is, therefore` an intimate co` operation between the two layers of bituminous material, as each serves to permit the use of' the other, and when usedinA combi- 8 nation. their beneficial characteristics are retained, whereas the disadvantages accompanying the individual use of either of the materials independent of the other are overcome. Y 9 In the construction Qof penetration macf adam" roadways, after a layervof coarse stone has been applied and rolled, and then a wearing surface of stone applied to the first layer and rolled, it has been .the cus- 9 tom to apply a very heavy binder which required heating to a temperature of from 300o to `l0()o F. Obviously, a binder requiring such a high heat-ing -soon thickens and the thin film'of dirt which necearily 'lq "remains onthe surface of the broken stone will act as a separator to prevent a union between the heavy `binder and the stone. This objection is overcome by the present method, as the `broken stone may first, be 1( treated with the penetrating and priming coat of light. and unhea'ted bitumen which unites with the stone and prepares the same for -receiving the heavy heated bitumen, which latter will then firmly unite with the 1] primingl bitumen, and' hence the broken stone.

The accompanying dia-wing illustrates in transverse vertical section, 'a portion of a water-bound macadam roadway construct- 1; ed in accordance. with my improved method. This type of roadway is illustrated merely for' exemplary purposes, it being-undef-- stood that the method is applicable to many other types. 1g

The portion of the road-bed indicated at A shows the condition of the same before treatment. That portion indicated at B has had the above described priming coat applied thereto, thc material of the ,priming 13 coat being represented at 1. Due to 'the high penetrating-value of the material of the priming coat, it is readily absorbed by the surface of the roadway` as above stated. That portion of the road-bed indicated at '1l C shows the condition of the saine after the application of the, heavier bitiiminous coating :i which, as indicated in the drawing.'` firmly adheres to the roaddied on account of the, provision of the priming coat.

The heroinbefore described cutting-back aetion of the priming coat 1 on the heavier bituminous coating 2 and the consequent carrying otI a portion of the heavier eoating down into the heart of the roadbeii is ropH resented in the drawing in section C", ln this. part oi' the drawingv` it will be noted that the portion of the toi,l` Coatingeut bark by the primingr roat rarried b v the prix ing coat deep into the heart ol' tin road-taak where its eementive value may be utilized This is ay result oi the retention of the gases or volatile matter in the road-bed by the hemier coating and the oonSequent cuttingn bark action which increases the penetrating value ofl a portion of' the heavier coating, and, therefore, the priming!` coat and the cutting-back portion of the heavier coat penetrate, deep into the road wasv. as illustrated in the drawing and as hereinbeire deSeribed.

1. The method of treatin;r road lief-is which consista in applying: to the road ,aar-` fare a penetrating` and primingT coat of' light bitmninous substance containing a ll rge per# eentagge ofi1 volatile matt-:fra eapalit: of Slow difi'usion, and thon before the volatile matters eL-Seape. appiying a coat of heavier bituminous substance capable of confining and retaining the volatile, matters in the road lied, the priming,r Coat being capable of binding the top coat to the road surface and of' gradually cutting back the saine to utilize its cementi ve value below the original road surface. l

The method of treating road-beds which consists in first removing the loose dust from the road surface, applying to the ele-ined road surface a penetrating and priming eoat of light bituminous Substance eontaining a large percentage of volatile .matters capable of slow diffusion, and then before the volatile matters escape, applying a coat of heavier bituminous Substance oapable of confining,T and retaining the. volatile matters in the road bed, the priming coat beingr capable of binding the top coat to the :road surface and of gradu iy cutting back the. same to utilize its cementive value below the original road surface. t

ln testimony whereof I affix my signature, .in presence of two witnesses.

SAM EVERETT FINLEY. "ivritnesses:

H. F. SMITH, Hoon Umswiimi.

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