早龄期混凝土半绝热状态温度分布与开裂研究

Study on Temperature Distribution and Cracking of Early-age Concrete in Semi-adiabatic State

采用红外测温装置研究了不同水灰比的早龄期混凝土的温度分布情况,发现相同环境温度下低水灰比的早龄期混凝土的半绝热温升高,且达到最高温度的时间短.利用数字图像相关设备研究了不同水灰比的早龄期混凝土的表面应变分布情况,发现不同水灰比的早龄期混凝土表面的应变集中区均出现在其骨料附近,且应变集中区出现的时间均在其最高温度出现之后.半绝热状态下,早龄期混凝土的开裂时间基本在其达到最高温度后的一段时间;早龄期混凝土表面首先会经历膨胀应变期,且膨胀应变先增大后减小,然后会进入收缩应变期,且收缩应变逐渐增大.

The temperature distributions of early-age concrete with different water-cement ratios are studied by using infrared temperature measuring device. It is found that the semi-adiabatic temperature of early-age concrete with low water-cement ratio is higher and the time to reach the peak of temperature is shorter at the same ambient temperature. The surface strain distribution of the early-age concrete is studied by using digital image correlation equipment. It is found that the strain concentration areas on the surface of early-age concrete with different watercement ratios all appear near the aggregate,and the strain concentration areas appear after the time to reach the highest temperature of the early-age concrete. The cracking time of early-age concrete in semi-adiabatic state is basically a period of time after it reaches the maximum temperature. The early-age concrete surface first experiences the expansion strain period,and the expansion strain increases first and then decreases,and then enters the shrinkage strain period,and the shrinkage strain increases gradually.