不同纳米碳酸钙含量对粉煤灰混凝土力学及抗冻性能的影响

研究了不同纳米碳酸钙掺量对不同养护龄期下的粉煤灰混凝土力学性能及抗冻融性能的影响,对掺杂不同纳米碳酸钙含量的混凝土试件分别进行了冻融循环试验,测定不同循环次数下的动弹性模量和相对动弹性模量;并构建了冻融循环粉煤灰混凝土损伤模型。结果表明:在一定范围内,掺杂纳米碳酸钙可以有效改善混凝土的抗压强度和劈裂强度;且对早期力学性能影响优于后期。纳米碳酸钙能够细化孔径,使得气泡间距减小,显著提高混凝土冻融循环次数,延缓混凝土相对动弹性模量衰减。当纳米碳酸钙用量为1.5%时,冻融循环125次后,其相对动弹性模量为82.07%,比未掺杂时提高了23.89%,混凝土的抗冻性能最优。

Effects of Nano-CaCO3 on Mechanical and Frost Properties of Fly Ash Concrete

The effects of nano-CaCO3 on mechanical and anti-frost performance of fly ash concrete were investigated. Freezing-thawing cycles were conducted on the concrete with different content of nano-CaCO3, after that dynamic elasticity modulus and relative dynamic elasticity modulus with different freeze-thaw cycles were measured. The freeze-thaw damage model of fly ash concrete was analyzed. The results indicate that the compressive strength and cleavage strength can be improved when a certain amount of nano-CaCO3 is added, especially in the early period. The nano-CaCO3 can refine the pore size to make the bubble spacing reduced. As a result, the freeze-thaw cycles and relative dynamic elasticity modulus was improved significantly. When the nano-CaCO3 content was 1.5%, the relative dynamic elasticity modulus of 82.07% after 125 freeze-thaw cycles, compared with ordinary concrete improved 23.89%. In addition, the performance of resistance to frost is better than others.