Field test study on early strain development law of mass concrete in cold weather

The early cracking of mass concrete in low temperature environment has always been a hot issue in the industry. The exploration of the development law of temperature and strain of mass concrete in low temperature environment is conducive to prevent its early cracking. Strain gauges are embedded in the upper, middle, and lower layers of the four measuring points of mass concrete on site to obtain the development data of early temperature and strain. Then analyze these data and reveal their internal laws. The following conclusions are drawn: (1) During the 0–30 h of concrete curing monitoring, the temperature in the middle layer of concrete is the highest, followed by the temperature in the upper layer, while in the subsequent monitoring period, a cooling gradient is formed from the lower layer to the upper layer. (2) The maximum compressive strain of concrete mainly occurs in the middle layer, and the maximum temperature and maximum compressive strain of concrete are positively correlated with its thickness. The ratio value of temperature difference between inside and outside of concrete and its thickness is the key factor affecting its external tensile strain. The strain of concrete decreases with the decrease of temperature and the development of strength, and finally tends to be stable. (3) The thickness of concrete has a significant effect on the complexity of the early strain development curve, but it does not affect the time when the strain development tends to be stable. (4) The decisive factor affecting the spatial correlation of concrete strain development is not its thickness and temperature, but the specific factors need to be further discussed.