Hydration of portland cement, natural zeolite mortar in water and sulphate solution

Abstract

The objective of this paper is to characterise sulphate resistance of mortars made from ordinary Portland cement ( PC ) and Portland-pozzolan cement with 35 wt.% of zeolite addition (zeolite-blended cement-ZBC ). 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 of Ca(OH)2 available for reacting with the sulphate solution to form voluminous reaction products. A decreased C3A, content due to 35 wt.% replacement of PC by zeolite is the next pronounced factor improving resistance of the mortar with such blended cement.

Keywords

• portland cement
• zeolite
• sulphate resistance