Effect of calcium leaching on the properties of cement-based composites

Abstract

Leaching is one of the major factors that alter the mechanical properties of cement-based composites. This study is aimed to investigate the effect of leaching on the properties of cement-based composites. Specimens with two water/cementitious ratios and two mineral admixtures were tested. An electrical potential was applied to accelerate the leaching process. Compressive strength test, scanning electronic microscopy, thermogravimetric analysis and X-ray diffraction analysis were conducted. Test results demonstrated that the calcium leaching reduced compressive strengths of concrete specimens, and such effect was prominent on the specimens without mineral admixtures. The leaching resistance increased with a decrease in water/cementitious ratio and an increase in amount of mineral admixtures. The mineral admixtures would reduce the amount of calcium hydroxide and refine the pore structure through pozzolanic reactions. A fair relationship was found between the calcium leaching and the compressive strength.

Keywords

leaching / slag / silica fume / X-ray diffraction analysis / thermo gravimetric analysis

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