Effect of entrained air on frost resistance of porous concrete

In recent years, the necessity of the environmental materials is increasing. Porous concrete has the large continuous void, and has high-permeability. Accordingly porous concrete has the ability of the purification, the vegetation and so on through this continuous void. This ability is applicable as environmental function on porous concrete. The aim of this study is to investigate the frost resistance of porous concrete. As ASTM C666 test is widely used for estimating frost resistance of concrete, in the case of porous concrete, it shows extremely low durability. So the uniqueness of this study is to apply RILEM TC-117 CIF test. This method is highly different from ASTM C666 method in water absorption and drain condition. And the one of main purpose in this study is to evaluate the effect of air entrainment on frost resistance. So, in this study, the air content in the cement paste varying as about 4% and 6%. Experimental result shows that air entraining is effective against the surface scaling of porous concrete as well as conventional concrete. On the other hand, ultrasonic velocity that indicates inner deterioration doesn't show any decline in all specimens. Also this study discusses an exposure test of porous concrete. There is porous concrete with air entrainment is applied for river protection of Hokkaido Naie-river in Japan, which is in the severe environment of freezing and thawing action. Measurement of ultrasonic velocity for five years shows no inner frost damage. As a result, air entraining is effective against frost damage on porous concrete.