Influence of drying on frost resistance of mortar using a nitrite corrosion inhibitor and paraffin waterproofing agent

Abstract The frost resistance of cement-based materials can be improved, by using the admixtures such as nitrite corrosion inhibitor (NCI) and paraffin waterproofing agent (PWA). In this work, we studied the influence of water curing and dry curing on frost resistance of mortars when these admixtures are added alone or in combination. Here, the cross sections of mortar samples were observed using the microscope equipped with a charge coupled device (CCD) camera and the pore structure was measured using mercury intrusion porosimetry. The results show that the frost resistance is similar to that of the reference mortars regardless of the addition amount, for the water-cement ratio W/C = 35%, but the frost resistance decreases regardless of the addition amount, for W/C = 55% when NCI is added alone. It is confirmed that the NCI may produce nitrite-type hydrocalumite and decreases frost resistance with the coarsening of pores. Furthermore, the PWA improves frost resistance by suppressing the effect of frost damage of hydrophobic compounds. This improvement is lessened when both admixtures are added in combination. This study advances understanding of the mechanism of suppressing frost damage by hydrophobic compounds.