基于Weibull分布的不同冻融介质下再生骨料透水混凝土耐久性能研究

Study on durability of recycled aggregate pervious concrete underdifferent freezing-thawing media based on weibull distribution

为探究不同环境下再生骨料透水混凝土(RPC)耐久性变化规律,以3种再生骨料替代率(0、30%、50%)和4种冻融介质(H 2O、3.5%NaCl、5%Na_(2)SO_(4)、3.5%NaCl+5%Na_(2)SO_(4))为变量进行冻融试验。定期测定RPC质量损失率和相对抗压强度损失率,对RPC取样并进行扫描电镜(SEM)分析,以冻融试验下RPC相对抗压强度损失率为依据,利用Weibull函数对RPC进行寿命预测。结果表明,同一环境下,RPC质量损失率和相对抗压强度损失率随着再生骨料替代率的增加而增加;同一再生骨料替代率下,3.5%NaCl、5%Na_(2)SO_(4)、3.5%NaCl+5%Na_(2)SO_(4)均加速RPC冻融破坏,3.5%NaCl+5%Na_(2)SO_(4)对RPC质量损失率和相对抗压强度损失率影响最严重。由SEM分析可知RPC内部孔隙和侵蚀产物数量均因循环次数和冻融介质的变化呈现明显的差异性,NaCl和Na_(2)SO_(4)对RPC侵蚀破坏起着相互促进的作用。由寿命预测结果可知,H 2O中RPC-0可靠度退化持续时间最长,即预测寿命最长,为4675 h左右,3.5%NaCl+5%Na_(2)SO_(4)溶液中RPC-50可靠度退化持续啥时间最短,为2200 h左右,表明NaCl和Na_(2)SO_(4)对RPC侵蚀作用较为严重。

In order to explore the durability change rule of recycled aggregate permeable concrete(RPC)under different environment,three kinds of recycled aggregate replacement rate(,30%,50%)and four kinds of freeze-thaw medium(H 2O,3.5%NaCl,5%Na_(2)SO_(4),3.5%NaCl+5%Na_(2)SO_(4))were used as variables to carry out freeze-thaw test.The mass loss rate and relative compressive strength loss rate of RPC were measured regularly.RPC was sampled and analyzed by scanning electron microscope(SEM).Based on the relative compressive strength loss rate of RPC under freeze-thaw test,the Weibull function was used to predict the life of RPC.The results show that under the same environment,the mass loss rate and relative compressive strength loss rate of RPC increase with the increase of recycled aggregate replacement rate.Under the same recycled aggregate replacement rate,3.5%NaCl,5%Na_(2)SO_(4)and 3.5%NaCl+5%Na_(2)SO_(4)accelerate the freeze-thaw damage of RPC,and 3.5%NaCl+5%Na_(2)SO_(4)has the most serious influence on the mass loss rate and the relative compressive strength loss rate of RPC.From SEM analysis,it can be seen that the internal pores and the number of erosion products of RPC are significantly different due to the changes of cycles and freezing-thawing media.NaCl and Na_(2)SO_(4)play a mutually reinforcing role in the erosion and failure of RPC.According to the life prediction results,the reliability degradation duration of RPC-0 in H_(2)O is the longest,which is about 4675 h.The reliability degradation duration of RPC-50 in 3.5%NaCl+5%Na_(2)SO_(4)solution is the shortest,which is about 2200 h.It indirectly shows that NaCl and Na_(2)SO_(4)have serious corrosion on RPC.