Experimental studies and analysis on compressive strength of normal-weight concrete at low temperatures

The construction of liquid nitrogen gas storages and engineering structures in cold regions exposed reinforced concrete structures to low temperatures. This paper investigates the compressive strength of normal-weight concrete under low temperatures to −165°C through a 174-specimen test program. The key parameters studied in this test program included low temperature T ranging from −165 to +20°C, water/cement ratio ranging from 0.33 to 0.57, and water content Wc ranging from 0 to 6%. Their influences on the compressive strength of the concrete under low temperature were highlighted and analyzed. With the scanning electron microscope (SEM), the influence of these parameters on the microstructures of the concrete under low temperature was observed and presented. These test data and SEM analyses revealed the failure mechanism and provided proofs on the improvements of the compressive strength of the concrete under low temperature. Based on these test data, a mathematical model has developed to describe the relationship between the increasing factor of the compressive strength of the concrete under low temperatures and the influencing parameters of T, w/c ratio, and Wc. Finally, design equations are provided to predict the increasing factor of the compressive strength of the concrete under low temperature.