The cause, effect, and prevention of cracks in latex-modified concrete (lmc) overlays were investigated. The types of cracks that occur in concrete, whether the concrete is lmc or conventional, are divided into two categories: internally caused and externally caused. Internally caused cracks are plastic and shrinkage cracks. As in anyquality concrete, lmc is subject to both of these if good construction practices are not followed. In addition, because lmc has a low water content, it has little bleed water available to evaporate and thus should be protected during placement if extreme drying conditions exist. Externally caused cracks include cracks caused by physical tearing, and flexural, reflective, and thermal cracks. All of these processes can be minimized or avoided by following proper construction practices. If cracking occurs in an lmc overlay, it is necessary first to determine the extent of the cracking before deciding on theremedy. Cracks that are shallow, 1/8 in. Deep or less, do not affect the permeability performance of the overlay. Deeper cracks, however, should be sealed. Laboratory studies of crack-sealing techniques indicate that the low-viscosity sealers are capable of filling most cracks and are recommended when full-depth penetration is required. This paper appears in transportation research record no. 1301, Factors affecting properties and performance of pavements and bridges 1991.
Abstract