硫酸镁腐蚀与弯曲荷载对碳化混凝土抗冻性的影响

EFFECTS OF MAGNESIUM SULFATE ATTACK AND FLEXURAL STRESS ON FREEZE-THAW DURABILITY OF CARBONIZED CONCRETES

在未加载与加载条件下,采用快冻法研究了快速碳化28d后的普通混凝土(ordinary Portland cement concrete,OPC),大掺量矿物掺合料混凝土(concrete with high content mineral admixture,HCMC)以及同时掺加大掺量矿物掺合料、膨胀剂、混杂纤维和引气剂的高耐久性混凝土(high durable concrete,HDC)在水和5%MgSO4(质量分数)溶液中的抗冻性。结果表明:碳化作用使HCMC的抗冻融破坏能力降低了56%,HDC的抗冻性几乎没有明显变化;MgSO4化学腐蚀与弯曲荷载及其耦合作用不同程度地降低了混凝土碳化后的抗冻性;与OPC和HCMC相比,HDC即使在使用过程中发生了严重的碳化作用,其在MgSO4化学腐蚀、弯曲荷载及其耦合作用下仍然具有较高的耐久性。

Through the method of accelerated freeze-thaw, the freeze-thaw durability of three kinds of carbonized concretes sub- jected to water and 5%MgSO4（in mass） solution with or without loading was studied. The considered concretes include ordinary Portland cement concrete （OPC）, concrete with high content mineral admixture （HCMC） and high durable concrete （HDC） added with high content mineral admixture, expansion agent, fibers and airntraining agent. Results show that the freeze-thaw durability of carbonized HCMC reduces almost 56%. Carbonation almost has no effect on the freeze--thaw durability of HDC. Effects of sulfate attack, flexural stress and their combination have different influences on the freeze-thaw durability of carbonized concretes. Compared to OPC and HCMC, although HDC is carbonized badly during the process, HDC also has high freeze-thaw durability under sulfate attack, flexural stress and their combination.