Improvement of Calcareous Sand by Using Chemical Grouting

In this paper, the improvement potential of calcareous sand produced in KishIsland by using a chemical grout is investigated. The main characteristics of this sand are its high voids ratio and tendency to be crushed under moderate stresses. The improvement process of sand is conducted using a sodium silicate grout injected with additives such as formamide and sodium aluminate. Samples were prepared in different initial relative densities and then grouted. It is observed that the maximum uniaxial strength, initial tangent modulus and failure strain are obtained in water/silicate ratio of 0.5.Uniaxial strength and initial tangent modulus are increased with time but failure strain variation with time is a function of water/sodium silicate ratio and additives content. Formamide increases and sodium aluminate decreases the uniaxial strength and initial tangent modulus. Furthermore, increasing of grain size decreases grouted sand uniaxial strength. Uniform grading results in brittle and non-uniform grading results in ductile stress-strain behavior. Presence of sulphates and chlorides solved in water reduces the uniaxial strength and increases the initial tangent modulus of grouted sand.