Study On The Anti-freezing Critical Strength Of Negative Temperature Concrete And Its Relationship With Durability

The damage of concrete caused by early age frost usually tend to benon-recoverable in Winter construction. The concrete often can’t reach its designstrength after curing for a certain age at normal temperature, at the same time, itsdurability reduced greatly. An important factor for negative temperature concreteto resist early frost damage is ensure its strength reached resistant freezingcritical strength before frost. Studies on critical strength of negative temperatureconcrete before concern a little influence factors and have little considerationabout its durability in the late period.This paper ma inly studies the critical strength of different strengthconcrete(C30,C40,C50)under certain condition, concerning adding anti-freezingadmixture or not and different frost negative temperatures(-5℃,-10℃,-15℃).As well as the frost resistance and impermeability of negative temperatureconcrete which has reach its critical strength at the later period were studied.Research shows that, the critical strength of concrete without antifreeze isnot a constant value. Resistant freezing critical strength grows with the growth ofstrength grade of concrete. The lower environmenta l temperature is, the highercritical strength the concrete needs. As to the concrete with antifreeze, there is noobvious regularity between the critical strength and different strength grades ordifferent frost temperatures. Antifreeze can not only shorten the procuring age,but also reduce the critical strength.The strength loss rate in later period of negative temperature concrete whichhas reached critical strength is less than5%, but the frost resistance lose rate isover5%, at the same time, the impermeability suffer different degrees of damagecompared with the control group which is in the standard curing condition. Thelater durability of negative temperature concrete is not satis factory. Negativetemperature concrete with durability require ment should extend its procuring ageaccording to the project construction situation.