Mix design and strength of soil–cement concrete based on the effective water concept

Abstract

Saturated surface-dry condition of fine aggregate has been well defined in mortar and concrete production as the dry mass percentage moisture content where aggregate particles are saturated. However in soil–cement concrete construction, no mix design based on the saturated surface-dry condition of soil was attempted partly because the control of soil moisture on site is difficult. We have proposed the definition and testing methods of the saturated surface-dry condition of soil in the previous papers. In this paper, we introduce the concept of effective unit water to the soil–cement concrete mix design and propose a mix design method for soil-sand-cement systems. Strength and density of the soil–cement concretes were determined and discussed. A number of mixes were proportioned with accurate control of composition (C/W, soil/sand ratio, free water, etc.) and consistency. It was found that strength can be determined by C/W for a wide variety of clayey soils in various soil/sand ratios except for a soil with very high content of organic material. A set of nomograms for C/W versus strength and soil/sand versus strength were presented for future proportioning.