DURABILITY OF FLY ASH CONCRETE SUBJECTED TO THE COMBINED EXTERNAL LOAD AND FREEZE-THAW CYCLES

摘要

In this paper, the durability of fly ash concretes made with different cement replacement percentage by fly ash (0% , 20% , 40% , 60%) and water to binder ratios (0. 3, 0. 35, 0. 4). is systemically investigated under the simultaneous action of external bending load and freeze-thaw cycles. The relative dynamic modulus (RDM) and weight loss are used as two important indices for evaluating the damage degree. Experimental results show that Fly ash content has great impact on frost resistance of fly ash concrete. For the concrete with high fly ash content, the weigh loss can be a sensitive index for evaluating the freeze-thaw durability, while RDME is very effective for measuring the frost damage of the concrete without or with low fly ash content. A reduction in W/B is helpful to enhance the resistance to freeze-thaw cycles. The larger the cement replacement percentage by fly ash is, the greater the damage is. External stress accelerates the degradation process of concrete exposed to freeze thaw cycles, it is especially evident for the concrete with high fly ash content.