渗透结晶型防水剂对PE-ECC力学和自愈合性能影响

Effect of cementitious capillary crystalline waterproofing materials on mechanical and self-healing properties of PE-ECC

为设计力学和自愈合性能优良的高延性水泥基复合材料(Engineered Cementitious Composite,ECC),以掺超高分子量聚乙烯短切纤维(UHMWPEF,文后简写PE)的ECC(PE-ECC)为基准组,掺入不同类型和掺量的水泥基渗透结晶型防水材料(Cementitious Capillary Crystalline Waterproofing Materials,CCCW),通过抗压、抗折、抗拉试验及预制裂缝法分别分析其力学和自愈合性能,并通过压汞法(MIP)、X射线衍射仪(XRD)和扫描电子显微镜(SEM)对其孔隙结构、物相组成和微观形貌进行分析。结果表明:随着CCCW掺量的增加,PE-ECC力学性能呈先增后减趋势,当掺量为1.0%时,其力学性能最佳,且掺XYPEX型CCCW对PE-ECC力学性能的提升更为明显,此时抗压强度为53.8 MPa,提升了37.95%;抗折强度为11.8 MPa,提升了53.25%;极限拉应力为5.56 N/mm^(2),提升了14.17%;极限拉应变为7.53%,提升了21.65%。通过对共振频率和裂缝宽度的变化情况分析可知,CCCW对PE-ECC的自愈合性能有明显提升效果,能有效修复宽度小于0.5 mm的裂缝。MIP测试表明CCCW能有效改善PE-ECC孔隙结构;XRD和SEM显示掺入CCCW后PE-ECC自愈合产物种类不变,但Ca^(2+)络合剂种类增加,提供Ca^(2+)能力变强;裂缝处自愈合产物分布更为密集,愈合程度更高。

To design an Engineered Cementitious Composites(ECC)with excellent mechanical and self-healing properties,ECC doped with ultrahigh molecular weight polyethylene short-cut fiber(PE-ECC)was used as a benchmark group and was mixed with different types and amounts of Cementitious Capillary Crystalline Waterproofing materials(CCCW).Compressive tests,flexural tests,and tensile tests were used to test their mechanical properties,and the prefabricated crack method was used to analyze their self-healing properties.XRD,MIP,and SEM were used to examine the phase composition,pore structure and micro-morphology of the materials.The results showed that the mechanical properties of PE-ECC tended to increase first and then decrease with the increase of CCCW doping.The mechanical properties were best when the doping amount was 1%.The mechanical properties of the PE-ECC were more obviously improved by XYPEX-type CCCW,with the compressive strength of 53.8 MPa,flexural strength of 11.8 MPa,ultimate tensile stress of 5.56 MPa and ultimate tensile strain of 7.53 MPa,which were 37.95%,53.25%,14.17%,and 21.65%higher than those in the reference group respectively.The change of resonance frequency and crack width showed that CCCW had a significant enhancement effect on the self-healing performance of PE-ECC,which could effectively repair cracks less than 0.5 mm,and the self-healing ability of both types of CCCW was similar.MIP test showed that CCCW could effectively improve the pore structure of PE-ECC.XRD and SEM tests showed that the types of self-healing products of PE-ECC remained unchanged after the doping of CCCW,but the types of Ca^(2+)complex agents increased,and the ability to provide Ca^(2+)became stronger.The distribution of self-healing products at the crack was denser,and the degree of healing is higher compared to others.