Simulation Analysis of Pumping Characteristics for High-Altitude Concrete

To investigate the characteristics of high-altitude concrete, the influences of atmospheric pressure on the air content, bubble stability, and pore structure of air-entrained concrete were tested by simulating a low-pressure condition using an environmental chamber. The pumping process was simulated using a resistance tester to investigate the effects of atmospheric pressure on the concrete slump, slump flow, V-funnel time, and pumping resistance. The results showed that the air content of air-entrained concrete decreases significantly with decreasing atmospheric pressure and that the pore structure of hardened concrete deteriorates. Among the admixture components, the effect of the air-entraining agent (AEA) on reducing concrete pumping resistance was the most evident. The pumping resistance of concrete increases at low atmospheric pressure, but that of concrete with AEA increases minimally. Combined with the ideal gas state equation, the air-entraining mechanism of high-altitude concrete was explained.