Effect of Temperature and Aging on the Mechanical Properties of Concrete

Abstract

In this dissertation, the mechanical properties such as compressive strength, splitting tensile strength, and elastic modulus were investigated experimentally according to temperature and aging, and the new prediction model about mechanical properties were proposed improving the shortcomings of previous models. Concrete is an aging material, and the mechanical properties of concrete change with time. Meanwhile, the heat of hydration in mass concrete structures makes the temperature gradient between inner and outer surface, and the temperature gradient affects the mechanical properties of concrete. The temperature variations by the cold-weather and hot-weather conditions also have the same influence on the concrete. Therefore, it is very important to estimate the mechanical properties of concrete according to temperature and aging. In order to estimate the characteristics of mechanical properties with temperature and aging, 528 cylinders were tested. Concretes were cured at variable curing temperature as well as isothermal curing temperature. Based on the experimental results, new relationships between compressive strength and splitting tensile strength or elastic modulus are proposed. According to the review of previous models by other researchers, the defects of the models were pointed out. Based on this examination, the new prediction model was proposed reducing the shortcomings of previous models. The validity of proposed model was also evaluated comparing the experimental results with the estimated values by new prediction model. The concrete subjected to high temperature at early ages attains higher early-age compressive strength but eventually lower later-age compressive strength. That is to say, the crossover effect is presented in the experimental results of compressive strength. Also, splitting tensile strength and elastic modulus has the same crossover effect as compressive strength. But the crossover effect of elastic modulus is not so obvious as ...