Use of coarse aggregate in controlled low-strength materials.

Controlled low-strength materials (CLSM) have evolved using only sand as aggregate filler. CLSM in the Pacific Northwest has evolved differently in that many mixtures use gravel up to 1 in. top size. The reasons for the use of gravel centre around economy and performance. Concrete technology teaches that the largest top-size aggregate that can be used yields the lowest voids in the combined aggregates. Reduced voids result in a lower paste requirement, which reduces the cost for cementitious materials.