Effect of Portland Cement on Soil Aggregation and Hydraulic Properties

Engineers have successfully employed portland cement to modify and stabilize soils for construction purposes (Highway Research Board, 1961). The use of cement as a soil amendment in agriculture has not been investigated. On hydration, the cement releases a considerable quantity of active lime (about 15% by weight of unhydrated cement), and cementitious amorphous and minutely crystalline reaction products (Stocker, 1963). Its addition to the soil in small quantities may improve soil aggregation and water stability, with consequent effects on soil-water retention and movement. The present Portland-cement cost of about 3 cents per kg. may not be prohibitive for its use on problem soils. The purpose of this paper is to present a laboratory study of the effect of additions of portland cement to a silt loam soil, at different rates and durations of moist-curing, on the amount and size distribution of water-stable aggregates, hydraulic conductivity of the saturated soil, the water-retention curve, and the unsaturated soil-water diffusivity. The duration of moist-curing is of potential importance because the hydration of several constituents in cement occurs at a very slow rate (Noble, 1968).