Microstructural effect of the shrinkage of cement-based materials during hydration, as indicated by electrical resistivity measurement

The effect of shrinkage during hydration on the microstructural change in cement-based materials was studied by measuring electrical resistivity and shrinkage strain. The microstructural change caused by shrinkage, as indicated by the fractional change in resistivity at the same shrinkage strain, is diminished with silica fume and increased with sand. The resistivity abruptly and irreversibly increases at a shrinkage strain of 3×10^-4. The increase is negligible when silica fume is present. The fractional change in resistivity per unit shrinkage strain is much larger than the fractional change in resistivity per unit compressive strain in the cured state.