US727505A - Pavement. - Google Patents

Description

No.. 727,505. PATBNTED MAY 5, 190s. P. J. WARREN.

` PAVEMENT.

APPLIOATION FILED MAY 15, 1901.

Patented may s, 1903.`

PATENT OFFICE.

FREDERICK .IOHN WARREN, OF NEWTON, MASSACHUSETTS.

PAVEMENT'.

`SPIECLEXIGATION forming part of Letters Patent No. 727,505, dated. May 5, 19.03.

Y Application filed May 16, 1901. Serial No. 60,450; (No specimens.)

base of mineral matter and a plastic unitingl medium consisting of a natural or artificial asphalt- .or coal-tar composition, which are intimately associated together and used as the main upper or top surfacing of the road-bed.\

The invention is based upon my discovery that to insure the best conditions of constru ction, wear, and life in such Ipavements the portion of the pavement to which 'my invention relates must be made as dense, as free from voids as possible, and also stable and non-liable to displacement, and uponl my further discovery that what has ordinarily .been supposed to be the best provision for eliminating voids and establishing stability has, as a matter of fact, been almost .the poorest provision .for accomplishing these purposes.' The provision usually accepted as the best is that in'which the mineral matterused as a basis of the pavementand united by the plastic asphalt vehicle shallvbe in the. shape of a sand or line gravel. ror, as I have, discovered by experiment that there is a smaller percentage of voids in a pavement which contains, mineral components which are of relati'vely largesize. v, The method has been in the construction of this class of pavements to exclude from its cornposition all pieces of stone or sand larger than one-tenth of an inch in diameter; but

` by so doing the smallest percentage of voids that it has been possible to produce has been twenty-one per cent. ot thetaggregate, while by the use of the'larger-sized grains or piecessay up to those whichwill pass through a two inch ring--and employing with` theselarger grains proper quantities ot the smaller sizes down to an impalpable powder it is possible to reduce the voids of the mineral base below ten per cent. of its bulk, and lsuch a This, however, is an ermixture when assembled and compacted to-l gether will form a dense, solid, homogeneous, compact body with the smallest percentage of voids and possessing the highest degree of stability, and one in which the largest and smallest pieces are associated with each other in'- discriminately throughout the structure, and one which, Ibecause of the sizes of the pieces and their arrangement with respect to each other, offers the smallest areas of surfaces for v the attachment of the plastic composition to them, so that not only -is a superior binding effect or union obtained`by the plastic composition buta smaller quantity of it is necessary for the purpose of obtaining the superior result or product. I prefer to use from one to three per cent. of impalpable powder, from tento thirty per cent. of material between impalpable powder and one-fourth 'of "an inch in size, and from fifty to eightytperv cent. 4of material .larger than one-fourth of t an inch in size. I have found that these'ingredients when associated together produce a mass or body having less than twenty per cent. of voids. I prefer to use as the uniting or plastic composition one which comprises asphalt and au voil-flux heated to a moderate i heat to provide the requisite fluid-ity; butI do not confine myself to any special form of artificial or ynatural asphalt.- It will -be uny derstood that the mineral components are not arranged lin the form of layers of. the same size, but are mingled with each other from theeupper to the lower surface of Ythe pavement, and that the plactic composition permeates the'entire mass, uniting-the various szedparticles.thereof, filling the voids, and forming the surfaces.

used as the upper or wearing section of arcadbed and that it 'may be covered, if desired, with a relatively thin surfacing of clear asphalt-ceme'nt or an asphalt or bituminous composition of any desired nature. In some instances there may be rolled into this Vthin surfacing while it is yet soft suicient sand, gravel, or-ine stone to` prevent its displacement by trailc. y

Iwill Inow describe .the invention in coul nection with the drawings, wherein'- l' Figure J1 is a view in horizontal section: of

enough of a pavement to illustrate in a con- It will be understoodthat thispavement is.

- ventional way the features of my invention,

while Fig`s. 2 and.3 are corresponding views .representing the addition ofva surfacing to the structure of Fig. 1.

In the drawings, A represents the portion of theA road-bed to which my invention relates and which may be called the wearingsection of the -road-bed and is the portion which covers and is supported by the macadam or other foundation B. In the wearingseetion are represented some of the'larger'mineral pieces, some pieces of intermediate size, and some of the smaller pieces and also the plastic composition Awhich unites themtogether, and C represents the surfacing to which I have referred. somewhat thicker in Fig. 3 than in"Fig. 2. It will be understood, however, that the drawings are simply illustrative and that it is not possibletorepresent the variations in the sizes-of the mineral pieces, atoms, and powder which are employedin producing my improved result.

In laying the wearing-surface the pieces, particles,r and atoms 4of the hase areintimately associated with the plastic asphalt composition, which is thenspread uniformly upon the prepared foundation and whichviu setting becomes very dense, solid, stable, and freer' from voids than any pavement of which I have knowledge. This density of the structure, stability, and its -relative freedom from voids Veryymuch improve the wearing properties of the pavement, its resistance to the action of water, and on account of its dense` structure prevents the volatilization or oxidation of the essential oils in the cementing medium, increases its life, and'while producing these improvements it alsoenables the wearing-surface to be produced at a smallerV cost because a smaller quantity of plastic asphalt materialis required than where the percentage of voids is larger.

A pavement or wea-ringsection of a pave-` ment having the features of this Ainvention possesses 'various advantages, among which vare the following: First, the percentage of mineral employed is-increased and the per-' centage of plastic uniting-medium decreased as compared with analogous pavements as` now laid; second, thewearing properties of the pavement are increased and improved, and this is due tothe employment of a larger proportion of mineral to the proportion of the uniting medium and also to the fact that the Y mineral base is of such a structure, owin g to the employment of a considerable percentage of relatively larger pieces, larger than are now used, that a very rigid and stable effect is obt-ained yandoue which reduces 4strain and wear upon the uniting medium, more of the wearV being borne by the mineral baseand less by the uniting medium than is common; third,

the interstices or 'voidsformed by such mineral components are also of a different character, in that they are larger and fewer, and therefore the asphalt or bituminous uniting It is represented as -l ireasons medium contained in them forms a cellular structure, which is stronger and adheres better to the surfaces of the mineral components numerous and of less size.

application, however,Ido not claim, broadly, a binder yor cement of this character. Ihave reserved the same to be claimed inmy cof pending application Serial No. 60,819.

Having thus fully described my invention, I

of the United Statesl. A street-pavement mixture composed of three inches down to an impalpable powder, from fifty to eighty per cent. off such mineral ingredients lying between one-fourth inch and three inches indiameter, in combination with a bituminous binder.

y2. A street-pavement mixture composed of mineral ingredients of several grades from an impalpable .powder to three inches in diameter, over fifty per cent. of such ingredients being larger than one-,fourth inch in diameter, and a bituminous binder.

3. A street-pavement mixture composed of tween one-fourth inch tothree inches in diameter, approximately ten to forty-nine per cent. between an impalpable powder and onefourth inch in diameter, and approximately one to three per cent. of an impalpable powder, in combination with a binder.

mineral or wearing ingredients, of which apfproximately fifty to eighty per cent. lies betweenone-fourth inch and three inches in di-A fourth inch in diameter, and approximately one tothree in combination with a bituminous binder, of Iwhich the soft, oily constituent is sufficiently great to render the binder itself too flexible to maintain the structure rigid.

5.- In a street-pavement, a bituminous min-` eralstructure, the mineral ingredients of whichfare mixed and of several grades, so graded as to give the structure an inherent stability. f

i5.' A bituminous street-pavementstructure containing mixed mineral ingredients of such grades as to give the structure an inherent stability.

7. A bituminous street-pavement mixture comprising a binder in combination with a y Because of the inherent Stability obtained' latter maybe as soft as desirable. In this!" claim and desire to secu reA by Letters Patentv mineral ingredients ranging in grades from 4. A street-pavement mixture composed of per cent. an impalpable powder,

than where the voids or interstices are more IOO mineral or wearing ingredients, of which approximately fifty to eighty per cent. are be- IIO ameter, approximately ten to forty-nine per cent. between an impalpable powder and one- K mineral structureol inherent stability composed of iwearing material of several grades uniformly mixed.

8. A street-paving mixture comprising a bituminous binder in combination with aY mineral structure 'of inherent stability.

9. A street-pavement Wearing-section composed of a. mineral structure of inherent stability formed of several grades of material so proportioned as to have a per cent. of voids less than twenty-oneper cent. of the whole, in combination with a comparatively soft bituminous binder filling said voids and rendering the Whole permanent `in nature and elastic and waterproof in character.

10. A mixture for street-paving purposes Vcomposed of a bituminous binder and a. mixture of mineral ingredients of several grades haviugless than twenty-one percent. of voids, the binder being sufcient in quantity to fill the voids.

l1. A street-paving structure composed of a mixture of mineral or wearing ingredients, and a plastic binder, the space between the one per cent. of the whole, and the-plastic l binder occupying said space. v

12. A mixture of mineral or wearing ingredients of several grades, the ingredients of the descending grades in size and quantity being so proportioned to each other and to the voids existing' in the larger grades as to fill the voids and impart t'o the structure an inherent stability, in combination Iwith a bi tuininous cement or binder.

13. A mixture to be used as a pavement having an inherent stability composed of mineral or wearing ingredients o f several grades,

the grades being thoroughly mixed and thereby uniformly distributed throughout the mass and being of sizes and quantities so propor-v tioned that ingredients of the same grade are uniformly in contact with each other, and a bituminous cement or binder.

FREDERICK JOHN. WARREN. Witnesses: i

F. F. RAYMOND, 2d, J. M. DoLAN.

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