The Durability of Composite Cement Paste Using Diatomaceous Earth against Sodium Sulfate Attack

Abstract

In this study, the durability against sodium sulfate attack test of composite cement paste using diatomaceous earth was carried out. Diatomaceous earth was calcined in several processes, in order to obtain micro-particles with a more dominant silica content which was used as a mineral material to produce composite cement. The proportion of diatomaceous earth in composite cement was 0%, 10%, 20% and 30% of total cement weight. The amount of water was determined, so that a composite cement paste with normal consistency was obtained. Composite cement paste was made by mixing all the constituent materials in a mixer. The specimens were made in accordance with ASTM standards, namely cubes with 50 mm sides with 9 specimens for each mixtures. The test was carried out by immersing the specimens in 10% sodium sulfate solution for one and two months then the visual changes, loss of mass and changes in compressive strength were observed. Composite cement paste that experienced smallest damage was composite cement paste with 10% and 20% diatomaceous earth. Mass loss was occurred only in the original Portland cement paste after two months immersion. The compressive strength of the composite cement paste experienced the least degradation at 20% diatomaceous earth content.