Ceramics-Silikáty 43, (2) 61 - 66 (1999)

The acidic resistance of mortars with cement to sand ratio of 1 : 3 by weight and w/c = 0.6 made from blended cement with 35 wt.% of zeolite and zeolite sand as well as that of Portland cement mortar attacked for 365 days by 0.5 %, 1.0 % and 1.5 % solution of hydrochloric acid is studied. The results show that the batch water volume required for the same plasticity level is 3.5 times higher in the mortar made from zeolite constituents compared to that made from Portland cement and siliceous sand. It is caused by higher specific surface area of the zeolite cement relative to Portland cement. This is consequently confirmed by higher water absorption capacity and total porosity of zeolite mortars. Typical symptoms of acidic attack is a decrease in weight, dynamic modulus of elasticity, strength, CaO content and ignition loss values and an increase in insoluble residue and chloride content in cement mortars. These are evidently the least in the zeolite mortar. Zeolite sand neutralizes HCl solutions contributing thus to the increased acidic resistance of zeolite mortar.