ABSTRACT
The experiments about compressive strength and freeze - thaw durability were carried on the concrete mixed two cements and two kinds of chemical admixture. Two cements were ordinary portland cement (OP) and high-early strength portland cement (HS), and two kinds of admixture were air entraining agent (AE) and antifreezing admixture (NF). The specimens in AE and NF concrete were mixed with OP and of 0, 20, 40 and 60% of the volume ratio of HS-content. The specimens, except for the standard curing specimens, were covered with only a 0.2 mm thick polyethylene sheet in the freezer with temperature of −1 to −6 C (30.2 to 21.2 F) after 24-hours placing. The compressive strength of AE and NF concrete cured in the freezer indicated about a half of the strength of standard curing concrete. NF concrete indicated slightly stronger rather than AE one. HS influenced slightly on 3-days strength of AE and NF concrete as HS-content increased, but inhibited the increase up to 28-days strength of NF concrete. Furthermore, NF concrete indicated enough freeze -thaw durability rather than AE concrete, and especially AE concrete without HS cured in the freezer had less durability. In a cold weather concrete using OP, we had better mix NF only in a concrete, or can mix over 40% HS -content with AE concrete if using HS.
