Infeluence of high temperature treatement on aircooled slag - dealuminated kaolin compositecement pastes

Abstract EN

This article aims to study the effect of temperature on the air-cooled slag-dealuminated kaolin composite cement pastes up to 800 oC.

Pozzolanic cement was prepared from 80 wt % ordinary Portland cement (OPC) and 20 wt % air-cooled slag.

The air-cooled slag was partially substituted by dealuminated kaolin (DAK) to prepare composite cement.

The results revealed that the standard water of consistency increases with increasing dealuminated kaolin content due to the increase of its surface area.

Cement paste made with 5 wt.

% dealuminated kaolin shows an acceleration of the initial setting time due to the nucleating effect and lor accurring dealuminated kaolin which increases the initial setting time of composite cement pastes is accelerated due to the higher activity of DAK in comparison with ACS.

However, the final setting time of composite cement pastes is retardered with up to 15 wt.

% DAK due to the increase of mixing water.

On the other side, 20 wt.

% DAK accelerates the initial and final setting times and decreases the liberated lime content as a result of its consumption by DAK hydration.

The effect of heat treatment was carried out by determining the ignition loss, bulk density, total porosity and compressive strength for the hardened cement pastes.

The products of thermally treated composite cement pastes were identified by using XRD techniques and visual inspection.