Effect of pore structure on the frost resistance of concrete

The pore structure of a partly frost-damaged engineering concrete which has been in severice for two years has been examined. Concrete cores were taken from both frost-damaged and undamaged locations. The freeze-thaw cycles, mercury intrution porosimetry (MIP), air bubble spacing coefficients analysis, petrographic analysis and SEM were carried out on these sampled cores. It was proved that distribution of pore diameter and the shape of pore also had influence on frost resistance of concrete, besides median pore diameter, the most passible aperture and porosity. Mechanism of air-entraining agent has also been discussed. Results of the cores taken from practical projects were consistent with those of accelerated experiments in lab. It indicated that frost resistance relied upon pore structure closely.