硫酸盐环境下再生混凝土早期强度的影响因素

Influencing factors of early strength of recycled concrete in sulfate environment

将建筑垃圾按照混凝土骨料试验要求进行处理后,制备不同水灰比、再生骨料掺量、循环周期等条件下的再生混凝土,对不同条件下再生混凝土的早期强度特征开展试验研究。结果表明:随着废弃建筑垃圾掺量的不断增大,再生混凝土的孔隙率、总进汞量、平均孔径均呈现出先减小后增大的变化规律,且在废弃建筑垃圾掺量为60%时取得最小值。根据试验结果表明,当经历硫酸钠溶液侵蚀后再生混凝土的抗压强度和抗折强度取最佳值时,硫酸钠溶液的浓度设定为5%,循环周期设定为30次,废弃混凝土、废弃砖以及废弃固结砂浆比例设定为6∶2∶2,水灰比设定为0.40,粉煤灰掺量设定为10%。过量的废弃建筑垃圾和产生的化学产物就会破坏再生混凝土内部的孔隙结构且再生混凝土内部产生了更多的裂隙等缺陷,使得混凝土内部孔隙率、总进汞量、平均孔径的变化规律开始增大。

The waste construction waste is used and treated according to the concrete aggregate test requirements to prepare recycled concrete with different water-cement ratio,recycled aggregate content,cycle period and other conditions.Carry out experimental research on the early strength characteristics of recycled concrete under different conditions.The results show that with the continuous increase of the amount of waste construction waste,the porosity,total mercury intake,and average pore diameter of recycled concrete all show a change law that first decreases and then increases.And the minimum value is achieved when the mixing amount of abandoned construction waste is 60%.According to the test results,when the compressive strength and flexural strength of recycled concrete after being eroded by sodium sulfate solution take the best value,the concentration of sodium sulfate solution is set to 5%,and the cycle period is set to 30 times.The ratio of waste bricks and waste consolidated mortar is set to 6:2:2,the water-cement ratio is set to 0.40,and the fly ash content is set to 10%.Excessive waste construction waste and chemical products produced will destroy the internal pore structure of recycled concrete and produce more slit defects inside recycled concrete.As a result,the change law of concrete internal porosity,total mercury intake,and average pore diameter began to increase.