Expansion Joints
It is recognized that brick will expand and contract with changes in temperature. When a bituminous or mastic filler is employed there is sufficient yield to the filler to accommodate the change in dimension in the brick, but when the grout filler is used either the expansion joint must be provided or the pavement must be designed to withstand the compression due to expansion of the brick. Expansion joints may consist of a sheet of bituminous mastic prepared for the purpose and set in place in the pavement. The sheet of joint material is simply inserted between courses of brick at the proper place.
Another method of forming an expansion joint consists in placing a strip of wood between courses of brick at the place where a joint is required. After the pavement has been grouted, the wooden strip is pulled out and the joint is filled with a suitable bituminous filler.
Marginal Curb.—If the sand bedding course is employed, it is necessary to provide curbing along the sides of the brick to hold the bedding course in place. The curb is usually constructed integral with the base and of concrete of the same mixture as the base. The width of the curb is usually six inches and the top of the curb is at the same elevation as the edge of brick surface.
Construction of the Surface
Before the construction of a brick surface should be undertaken on a road, the drainage should be provided for even more completely than for a less costly type of surface since it does not pay to jeopardize the stability of the pavement by failure to provide adequately for the stability of the supporting soil. Grades should also be reduced to the economical limit.
The earth subgrade is brought to the proper elevation and cross section and is thoroughly rolled. If there are places where the soil will not compact properly under rolling, these places are corrected by taking out the material and back filling with new material that will properly compact under the roller.
The aggregates for the concrete may be distributed along on the prepared subgrade or may be stored in stock piles or bins at convenient points. If stored on the subgrade, a traction mixer is employed which is drawn along the road as the work progresses, the materials being placed directly in the mixer. If stored at a central point, they may be transported to the mixer on the road and dumped directly into the mixer, or the mixer may be set up at the storage piles and the concrete hauled in trucks to the road where it is deposited and shaped.
The concrete is spread to the proper thickness and tamped either by hand or by machinery. If the marginal curb is to be employed, it is constructed immediately after the concrete for the base has been finished but before the cement begins to set.
After the foundation concrete has set, the bedding course is spread and struck off to the proper thickness. When the bedding course consists of sand-cement mortar, the sand and cement are mixed dry and spread to prescribed thickness. It is considered to be desirable to roll the sand bedding course with a light hand roller before the brick are placed, but the sand-cement bedding course is not rolled. The bedding course must be carefully shaped by means of a templet or strike board before the brick are placed.