Effect of mechanical grinding on the hydration activity of quartz in the presence of calcium hydroxide

Abstract

In order to explore the hydration conditions of quartz powders at room temperature, pastes containing quartz/lime at a ratio of 4:1 were prepared at a water/cement ratio of 0·4. The effect of mechanical grinding on the hydration activity of quartz was investigated based on determination of the compressive strength, the mineral phase composition, calcium hydroxide consumption and the quartz reaction degree of hardened samples of quartz/lime pastes under standard curing conditions (temperature of 20 ± 1°C and mass of 95%). The results revealed that grinding had an observable impact on the hydration activity of quartz. The compressive strength of the quartz/lime pastes increased from 0·34 MPa to 1·59 MPa after a curing period of 140 d, and the specific surface area increased from 227·2 m2/kg to 729·1 m2/kg. Moreover, a small amount of CSH gel was detected in the test pastes. This indicates that quartz has the capacity to react with calcium hydroxide and shows some pozzolanic activity at room temperature under mechanical activation and after a long curing period.