Salt-frost scaling testing HVFA concrete to -52C: internal cracking measured with dilatometry

We investigated the overall salt-frost resistance to extreme temperatures of well-cured HVFA concrete with w/b= 0.40 with and without air entrainment. Horizontal length change measurements were made using invar steel dilatometers equipped with LVDTs during freeze-thaw cycles to -52 °C with 3 % NaCl covering the horizontal test surface. The dilatometry showed how the well-spaced air voids worked to protect concrete. During individual cycles dilation larger than fracture tensile strain was seen from -40 °C to -52 °C starting already at the first cycle. Possible reciprocal effects between scaling and cracking were seen with the larger acceleration of the scaling of the non-air entrained specimen.