【摘要】 通过对四种不同配合比的混凝土先后进行冻融循环试验(0、50、150次)和加速碳化试验(0、1、2周),研究冻融前后混凝土碳化性能变化情况。结果表明:冻融循环增大了混凝土孔隙率,加速了碳化进程,循环次数越多,加速作用越大;在冻融和高浓度CO2环境下,粉煤灰的掺入增加了混凝土碳化量,并造成较大强度损失,对混凝土结构不利;碳化使混凝土抗压强度略有提高,但不足以弥补冻融造成的强度损失,水灰比越大,强度损失越大。对混凝土结构进行耐久性设计和使用寿命预测时,必须考虑冻融、碳化及其它因素的复合作用。更多还原

【Abstract】 Four different types of concrete had been studied after exposure to 0,1,2 weeks carbonation after 0,50,150 freeze-thaw cycles to investigate into the effect of freeze-thaw action on carbonation of concrete.Results show that increased porosity,which is induced by freeze-thaw cycles,accelerated the carbonation process;and this accelerating effect becomes more evident with increasing number of freeze-thaw cycles.If exposed to freeze-thaw cycles in an atmosphere with high CO2 content carbonation of concrete prepared with fly ash is particularly accelerated;and its compressive strength is sharply decreased.The compressive strength of ordinary concrete increases slightly by carbonation but is reduced by the combined action of freeze-thaw cycles and carbonation;the strength loss becomes more evident as the water-cement ratio increases.Freeze-thaw action,carbonation and other deteriorated factors should be taken into account with respect to the durability design and service life prediction of concrete structures.更多还原