A study was undertaken to evaluate the stabilisation or modification of sands and clays using ASTM Class C fly ash as a full or partial replacement for hydraulic cement or hydrated lime. Strength and durability tests demonstrated that the Class C fly ashes of the study could be substituted for cement in some sands. Improvement of the sands was provided by the matrix formed with fly ash acting as a filler and as a cementing agent. The test results indicate the importance of the gradation characteristics of the materials and the effects on matrix quality due to the presence of fines in the natural sands. Also, improvements in the plastic properties and gains in soil support with the addition of fly ash and/or lime were evaluated for two clays. However, test results and analyses demonstrated that the Class C fly ash does not effectively compete as a substitute for lime in the treatment of clays.
Abstract