Effect of moisture content on freeze–thaw behavior of cement paste by electrical resistance measurements

Abstract

The electrical resistivity responses of cement pastes with different moisture content under cyclic freeze–thaw (F–T) action are presented. Different moisture content was achieved using water adsorption. Ordinary cement paste samples with water-to-cement (W/C) ratio of 0.5 were used in resistance measurements. Cyclic F–T tests show similar curves of resistivity versus temperature, but with different characteristic parameter values. Depercolation during freezing and repercolation during thawing occur, and the percolation electrical resistivity remains almost constant at around 2000 (\(\rm \Omega \,\rm{m}\)). The depercolation temperature \(\theta _{\mathrm{DPT}}\) is systematically higher than the repercolation temperature \(\theta _{\mathrm{RPT}}\), and both show slight increase with F–T cycle, but decrease with moisture content. The freezing temperature \(\theta _{\text {FT}}\) and melting temperature \(\theta _{\mathrm{MT}}\) increase with moisture content but exhibit minor change with F–T cycle. The plots of electrical resistivity–temperature curves confirm an Arrhenius type equation during both the freezing and thawing. Augmenting moisture content tends to lower the activation energy of resistivity.