Synthesis, Chemical, Thermal, Electrical and X-Ray Diffraction Analysis, and Hydration of Portland Cement - Zeolite Mortar in Water and Sulphate Solution

摘要

Sulphate resistance of mortars made from ordinary Portland cement (PC) and Portland – pozzolan cement with 15 - 50 wt. % of zeolite addition (zeolite – blended cement - ZBC) has been characterised in this paper. The use of zeolite-blended cements varies according to the application conditions and availability of suitable materials. These cements are applied in clay - cement suspensions for slurry cut-off walls and concrete exposed to aggressive environmental conditions mainly due to increased resistance to acid and sulfate solution. Mortars with two different cement types were tested in water and 5 % sodium sulphate solution for 720 days. A favourable effect of zeolite on increased sulphate resistance of the cement is caused by decrease in free Ca(OH)_2 content of the mortar. There is not sufficient amount of Ca(OH)_2 available for reacting with the sulphate solution to form voluminous reaction products.