Laboratory investigation of the permeability properties of cement mortar with different sand–cement ratios

Abstract

The influences of the sand–cement (s/c) ratio and microstructure on the water permeability of cement mortar were examined. Laboratory experiments were carried out to study the influence of the s/c ratio on the seepage failure of cement mortar. The results showed that the contacts of aggregate grains can be divided into three types – wrapped contacts, surface contacts and point contacts. The relationships among water permeability, porosity and wave velocity of cement mortar were also investigated and it was found that the permeability coefficient of cement mortar increases exponentially with an increase in the s/c ratio. It was also found that there is a critical s/c ratio range (around 5–6), at which the porosity and wave velocity change remarkably. When the critical s/c ratio is exceeded, the critical seepage pressure is reached and seepage failure occurs. The relationship between the permeability coefficient and the critical seepage pressure was found to be a power function.