Pavement Performance As A Basis For Design

The assumptions in the Westergaard and Burmister theories for the design of concrete pavements, and the use of some empirical equations in the design are discussed. The results of load tests on seven concrete slabs with different foundations are presented. These tests were performed 1 yr after the construction of the pavement, i.e., when the separation (or break in continuity) between the slab and its foundation is likely to have taken place. The data on subgrade moisture content, warping and temperature distribution in the concrete slabs, pavement deflection and stresses and subgrade pressures are presented. Revised equations are given for: (1) Modulus of subgrade reaction, (2) interior, corner and edge load deflection, (3) corner and edge load stress, and (4) edge stress when cracking takes place parallel to the edge (for thin slabs). The equations show that the deflections and stresses due to corner and edge loading are not a direct function of load P but P^0.67 and P^0.8, respectively.