US888886A - Pavement and method of making the same. - Google Patents

Description

'WILLIAM HooGHToN, or Bos'roN, MASSACHUSETTS;

PAVEMENT AND METHOD OF MAKING THE SAME..

no. sea-sec.

Specification of Letters Patent. Application filed September 23, 1907; Serial No. 394,092.

Patented May 26, 1-908.

To aZIwho'm it may concern: I

Be it known that I, WILLIAM S. HOUGH- TON, acitizen of the United States, residing at Boston, in the county of Suffolk and State of Massachusetts, have: invented a certain new and useful Improvement in Pavements or Roadways and Method of Making the Same, of which the following is a full, clear,

, and exact specification, reference being had therein to the accompanying drawings.

This invention re ates to pavements or roadways-and especlally to pavements which are monolithic orlaid in one course.

' Heretofore, it has been customary to lay pavements in courses or layers. The most common type of such'pavement comprises three courses, namely, a: substratum or foundation, a binder course and an upper layer or wearing surface, The binder course is relied upon, in such cases, to bind the wearing surface to the foundation and is generally made of-bituminous .or other similar material of strongly adhesive qualities. In other cases, the binder course is disensed with and a' bituminous Wearing surace employed, in which event, the adhesiveness of the wearing course binds it to the foundation. It is necessary to the life of such pavements, however, that the courses or layers should at all'times remain firmly bound together; but frequently, owing to the fact that the bituminous binder or the bituminous wearing surface is softened by heat andthe adhesion of. the wearing surfaceto the underneath layer thereby lessened or destroyed, the. wearing surface, when subjected to the pressure of traffic, slides, rolls or buckles and breaks up.' This has been the principal difficulty-With pavements laid .in courses and this defect has never been entirely eradicated.

The'object of my invention is to provide a avement of durable construction which can e laid with facility and economy, and which will not slide, buckle or seam, and I accomplish this purpose by constructing the pavement in one layer which is an integral o'dy or mass, homogeneous in structure.

In the accompanyin drawing, which illustrates the preferred em odiment of my invention, I have shown a vertical cross-sectional view of a portion of a pavement.

Referring to the drawing, 1 represents a curb; 2 broken or crushed stones; and 3 the sand and cement and sand and screenings. a p

In making my pavement, I first prepare a mixture of sand, dry cement and crushed or broken stone, the last mentioned material ranging size preferably from screenings to two inches in diameter, and constituting about ninety per cent. by Weight of said mixture. After the above ingredients, have been thoroughly mixed together, they are treated with liquid bitumen,-oil or coal tar .or liquid'asphalt, in such a manner and to such an extent as .to coat the particles of sand, stone and cement. This mixture is laid 1n a solid mass or layer upon the ground= which shouldpreviously be smoothed to receive it, and then rolled to form a close The depth of this layer homogeneous mass. may vary from four to eight inches to'oonform to the requirements ofthe pavement. The liquid bitumen acts as a binding material to unite the various particles of sand and crushed stone. The amount of liquid bitumen, oil-or coal tar or liquid asphalt to be used will depend somewhat uponthe size of the stony elements, but enough should be used to coat the particles either partially or entirely.

When the pavement has been thoroughly rolled and compressed, I next mix together dry cement and screenings and spread the mixture over the surface of the pavement in a-thiu layer. The pavement is then sprinkled with water which washes the mixture of screenings and cement into the voids of the. pavement, fills them up, and the cement sets.

The Water thus sprinkled on the pavement also percelatcs through the voids and causes the dry cement throughout 'the. pavement ,WlllGli has not been a i'ected by the liquid bitumen, tar or asphalt to set and thus fills up all the-voids completely and forms a close and dense mass. Ifnecessary, a second coating'of the mixture of screenings and dry cement maybe sprinkled on thepavmen't and treated with wateras above described,

for the purpose of filling any voids which may not have been entirely closed up by thefirst application.

In making my pavement, I preferto use the bitumen, coal tar, asphalt in'liquid form because the particles of stone, sand and cement are thereby more easily and efficiently coated and the expense and'labor of loo roviding heating means is dispensed with.

extremely cold weather, it way, however, be necessary to em loy heating means but under ordinary con itions, my pavement can be constructed without any heat.

By employing a bituminous substance in liquid form as a binder in addition to the cement, I secure a pavement which is yield- .adapted to such use owing to the fact that ing and elastic and therefore less liable to break up or seam when subjected to strain than a pavement where cement alone is used. At the same time by using cement, I secure great strength and wearing qualities.

My invention may also be a plied to resurfacing old macadam roads and is especially the old materials may be used and a great saving in, materials thereby eflected. In

such'a case, I tear oil the old macadam,'

screen out the stone and mix itas previously described. The screenings fromthe old road are also used in the same manner as heretopresent time With'respeot to the ordinar macadam or concrete roads. known fact-that the high speed lncident to It is a wel automobile travel causes a strong suction under and to the rear of the automobile as it travels over the road and the suction' so generated soon destroys the surface of the road by drawing out the fine particles or dust between the larger stony elements, and leaving large voids which sooner or later cause the surface of the road to be broken up and disintegrated.

Another advantage derived from constructing my pavement in one homogeneous mass, is that in case of leaks-in the gas or water mains in the street, the gas or water cannot affect the pavement. Where roads are constructed in courses or layers, it is frequently feund that gas or water leaking from the mains idrces its way between the courses and destroysthe road Where gas gets under the wearing surface it forms a cushion and the wearing surface rolls or waves when used and ultimately breaks up.

Water will effect the same final result by washing sand up between layers.

Since my pavement is all'wearing surface, it may be laid in varying'fthicknesses to sult the use. For example, in a parkwayfwhere never be destroyed until the pavement has been Worn down to such an extent that the trafiic pressure will break it up, and therefore, it is well adapted to long and continu-' ous use. 1

' What I claim is: l v 1 A pavement, consisting of a single layer or course of a mixture of crushed or broken stone, sand and cement in such proportions as to leave voids, the pieces and fragments of said mixture being coated with bituminous material and compacted and bonded together into a single homogeneous layer or course, the voids in saidcourse being occupied by a cement mixture.

1 -'2 The process of making a pavement consisting in preparing a mixture of sand,'dry cement and crushed or broken stone in such proportions as to leave VOlClS when laid,

treating the said mixture with bituminous material in. order to coat the fragments and particles in said mixture, layiu the treated mixture in a single course, rol ing the said course until it is compact, spreading upon the top'of said rolled course a layer of sand or screenings and dry cement and then washing the said layer withwater into the voids in said course and thereby filling said voids.

In Witness whereof, I have hereunto set my hand, in the presence of two subscribing witnesses, this the fourthday of September, 1907.

WILLIAM SiHOUGHTON. \Vitnessesi UNIAC,

. lrmimns FfRzonannsoN.