海水侵蚀作用下的海水海砂混凝土损伤研究

Study of damage to seawater sea-sand concrete under action of seawater erosion

为了研究海水侵蚀作用下海水海砂混凝土(seawater sea-sand concrete,SSC)的耐久性损伤规律,通过设计海水海砂对淡水河砂替代率分别为0、100%和粉煤灰对水泥的替代率分别为0、10%、20%的混凝土试块,分析海水侵蚀20、40、60 d后的混凝土强度损失率、质量损失率和相对动弹性模量随海水侵蚀时间增长的变化曲线。结果表明,SSC与普通混凝土(ordinary portland concrete,OPC)的耐久性能损伤程度均随侵蚀时间的延长而不断加深,但海水侵蚀对SSC耐久性的影响大于OPC,粉煤灰的掺入可以通过微集料效应及火山灰反应促进二次水化反应提升混凝土的密实度,从而加强SSC的抗侵蚀能力。通过灰色系统理论的均值GM(1,1)模型建立的损伤预测模型符合一级预测精度要求,可以对海水侵蚀作用下的SSC损伤进行准确预测。

To study the durability degradation law of seawater sea-sand concrete(SSC)under the action of seawater erosion,concrete test blocks were designed with 0 and 100%substitution of seawater sand for freshwater river sand,and 0,10%and 20%substitution of fly ash for cement,respectively.The curves of strength loss,mass loss and relative dynamic elastic modulus of concrete with increasing seawater erosion time after 20 d,40 d and 60 d of seawater erosion were studied.The results show that the degree of degradation for both SSC and ordinary portland concrete(OPC)increases with the extension of the erosion time,but the effect of seawater erosion on the durability of SSC is greater than that of OPC.The incorporation of fly ash can enhance the compactness of concrete through the microaggregate effect and the volcanic ash reaction to promote the secondary hydration reaction,thus strengthening the erosion resistance of SSC.Finally,the damage prediction model established by the mean GM(1,1)model of grey system theory meets the requirements of first-class prediction accuracy and can accurately predict SSC damage under seawater erosion.