US2259374A - Road construction - Google Patents

Description

Oct. 14, 1941. C'. u. GRAMELSPACHER 2,259,374

ROAD CONSTRUCTION Filed oct. 8, 1958 2 sheets-sheet 1 uapnce Duessm 7 Tau. on. O\\

5TONE ov. CoNcle-rs EHQTH Wonu BED- INVENToe 0t 14, 1941. c. u. GRAMELsPAcHER 2,259,374

ROAD CONS TRUCTION Filed Oct. 8, 1958 2 Sheets-Sheet 2 Cmnmce U. GnaMiLsPacHm Patented Oct. 14, 1,941

AUruTeo STATES PATENT OFFICE '1 Claim.

This invention Vrelates to the construction of roads and pavements, and more particularly to a road or pathway constructed of wood or timber in the form of plies, together with an appropriate binder and ller material.

The invention consists in providing a road or pavement of b-uilt-up layers comprising a rigid waterproof base with plywood laid thereon to form the body of the roadway with a mastic waterproof surface coating covering the top and sides of the plywood.

Wood in the form of blocks has been used heretofore in the construction of pavements. In this type of pavement construction, however, wood 'blocks are exposed directly to the Wear of trafiic as well as the surrounding climatic conditions.

The wood block is usually treated with creosote oil to preserve the wood and prevent the absorption of water which causes swelling. Treated wood, however, will absorb some water and only i* by thorough and proper treatment can this be reduced in amount so as to obviate trouble from swelling.

Aside from the difficulties encountered by swelling, wood block pavements exhibit a high degree of slipperiness when wet which is very objectionable. Bituminous bonded road surfaces, asphalt pavements and the like are superior to Wood in this respect but are inferior to wood in the resistance offered to wear under heavy traffic conditions. Further, due to the pushing force or pressure exerted against the surface of asphalt or bituminous pavements, by motor vehicle trafc, distinct waves or bumps are produced. Sometimes this occurs in recently built pavements. To overcome this defect various methods have been devised involving a more careful selection of materials and more expensive road construction, but the problem has not been entirely solved.

This invention overcomes these defects and provides a highly improved road or pavement construction.

An object of this invention is to provide an improved pavement or road construction which is inexpensive to build, highly resistant to distortion under traffic, and very durable.

Another object of this invention is to provide an improved roadway or pavement which utilizes the combination of wood and a suitable surface dressing to produce a highly improved, inexpensive roadway or pavement.

Another object is to provide a road wherein the body of the highway surface comprises plywood. Such a roadway is highly resistant to impact and surface distortion and raveling commonly observed in bituminous aggregate constructed roads and pavements.

Another object is to provide a roadway having laminated wood slabs positioned beneath the traveled surface of the highway in order to pro- -d-uce an antirippling roadway.

the drawings:

Figure 1 'is a perspective view of the construction' of V-the roadway showing the diiferent layers ithereof;

VFigure -2 is a cross sectional view of the roadway 'orpavement constructed according to this in vention;

Fig-ure `Bjis an elevation view of the road surface prior -to applying the surface dressing;

Eig-ure 4 `is -a View similar to Figure '3, illustrat- :ing `the cutting and laying of the timber employed;

rFigure 5 is a fragmentary view in section of the plywood sheet or block employed, showing the cross grain arrangement of the diiferent plies;

Figure 6 Vis a sectional view of a modified road construction similar to that illustrated in Figure 2, with certain parts broken away.

Referring to the drawings in detail, the numeral 1 designates a roadbed which is shaped to conform to the surface of the finished roadway or pavement. Over the roadbed is applied a waterproof coating 8 of tar, oil or the like. Any waterproofing substance may be employed, but preferably a tar or heavy oil product of coal gas, water gas or coke oven is used. Creosote oil or equivalent heavy oil may be employed either alone or mixed with tar. A mixture of tar and creosote oil is somewhat superior as a waterproofing agent to either of these substances alone.

After the application of a waterproof coating to the roadbed surface, a layer of stone or concrete 9 is applied thereover of desired thickness and then another waterproofing layer 8 of tar, oil, or a mixture thereof, is disposed over the surface of stone or concrete. This seals the concrete, rock or stone section against the penetration of moisture or seepage of water from surrounding earth. Upon the waterproof layer 8 is placed a sheet 0r covering I of building paper, libre, plastic or pulp board in order to present a smooth, regular surface forming a cushion for the plywood slabs Il laid thereon. In some instances the paper or libre board covering may be omitted. As an alternative the cushion layer I0 may comprise a bituminous mastic of hot tar or asphalt mixed with sand. Sand may be omitted and tar alone used as another modificationl The plywood slabs II, as shown in Figure 5, comprise alternate cross-grained laminated plies of relatively thin sheets of wood IIa held together by glue or resinous material I2 conventionally employed for this purpose. For providing greater rigidity the central plies can be made thicker than the outer sheets. The dimensions of the plywood slabs may be varied; in general, however, they are of sufficient width to extend across substantially one-half the roadway surface. Two such slabs are laid with their ends abutting together at or near the center of the road as shown in Figures 1 to 4, and covered with surface dressing. Due to the crossgrained laminated construction of the ply-,-Y

wood expansion of the slabs is compensated for and no special joints need be provided. Therplywood slabs may be laid eitherY Yparallelto the curb, similar to the manner of laying brick, or diagonally, as illustrated in Figures 3 and 4, re-

spectively. f Y

' Over the layer of plywood is ap'plied a surface dressing I3 of bituminous bonded aggregate. Mineral aggregate employed for this purpose Amay be crushed stone, slag, gravel, grout, and the like, the particles smaller than l@ inch in diameter being omitted. Preferably aggregate having particles ranging in size from 1/2 to 1% inchesin diameter is used. A surface dressing of hot bitumen or asphalt mixed with coarse sand may be applied directly over the plywood ifr desired with or Awithout the use of other ag gregate. This construction makes the pavement thoroughly waterproof and provides for somel slight expansion of the wood inlaid therein.

The wood or'timber plies making up the plywood are preferably treated with preservative, such as copper sulphate, zinc chloride, bichloride of mercury and creosote to prevet the attack of .wood destroying fungi and insects.

In the modification shown in Figure 6 the outer margins of the plywood slabs abut against a concrete shoulder I4 which may be extended to form the curb and gutter adjacent the roadway or pavement. The space between the outer edges of the plywood II and the concrete shoulder I4, as at I5, will be filled with tar or the surface dressing I3 employed to cover the plywood in the construction shown in Figures 1 and 2. In this way the plywood will be thoroughly sealed from the atmosphere and maintained waterproof.

As a further modification the surface coating I3 may comprise concrete or brick. If desired a combination of concrete and brick sealed with tar or equivalent material may be employed as a surface dressing for the plywood. In this connection, the terms bonded aggregate refers to the Yuse of cement for binding the aggregate as well as bituminous or other suitable agents.

In the construction of roadways and pavements as disclosed by ths invention, comprising embedded plywood slabs, a resilient highway is provided which is exceedingly durable and is considerably less expensive to build than the convention-al hard surface roads.

It is understood, of course, that this invention is not limited to the exact details of construction since obvious modications may be made by persons skilled in the art Within the scopevof the disclosure and appended claim.

- Having thus fully described by invention, what I claim asnew and desire to secure by Letters Patent is:

An improved roadway or pavement construction comprising a roadbed surface having a Waterproof coating thereover, a hard road foundation surface layer laid thereon, a waterproof coating disposed oversaid hard foundation surface, a cushion layer of sheet material laid over said waterproof coating, cross-grained plywood slabs disposed on said cushion layer, and a waterproof road surface dressing cover layer appliedoverthe top and side surfaces of said plywood, said plywood being thoroughly sealed against contact with water.

CLARENCE U. GRAMELSPACHER.

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