Effect of a Synthetically Modified Natural Zeolite Additive on Properties and Durability of Cement Mortars

Abstract: Durability characteristics of cement mortars and concrete are of interest to various researchers and practitioners in the field of construction materials engineering. This study evaluated the potential use of a semi-synthetic zeolite additive for improvement of cement mortar properties. The product, a blend of selected alkaloids and zeolite is commercially available and effectively used in soil stabilization for road construction. However, its influence and effectiveness on properties of cementitious systems has not been explored. Emphasis of this study was on durability of cement mortars. This was assessed using the durability index approach being advanced in South Africa. The additive was added to standard mortars of 0.5 water-cement ratio, prepared according to EN 196, in proportions of 0%, 0.4%, 0.6%, 0.8%, 1.0%, and 2.5%. Tests carried out include compressive strength, oxygen permeability, sorptivity and resistance to sulphate attack. It was found that the additive significantly improves durability characteristics while increasing strength and workability when used at optimum proportions. Its use in proportions between 0.4 to 0.6% additive gave optimum results in most tests. Further increase in the additive proportion tends to be counter effective, especially at above 1% additive. The low optimum proportions found also favour economic considerations