For conventional concrete, F-T resistance of concrete largely depends on aggregate quality,
concrete air void system (especially the void spacing factor) and strength (especially the strength
of the interfacial transition zone between aggregate and cement paste). It is well accepted that
concrete with void spacing factor of 0.008” (200 micrometer) generally has good F-T resistance.
In PCPC, void system may be less important due to the open structure of the material. As
mentioned above, the calculated average paste thickness around aggregate particles in the most
PCPC mixes studied is approximate 0.008” (200 micrometer), which indicates that requirement
for AEA might be arbitrary. However, it was observed under microscope that the paste thickness
in some regions of the PCPC was often larger than the average value. Therefore, AEA is still
recommended for the PCPC application under a cold weather condition until further research is
conducted.