水泥基渗透结晶型防水材料和纳米二氧化硅改性混凝土自修复性能的研究

Self-healing Properties of Concrete Modified by Cementitious Capillary Crystalline Waterproofing and Nano-silica

为研究水泥基渗透结晶型防水材料(CCCW)与纳米二氧化硅(NS)对混凝土自修复性能的影响,制备了基准混凝土、单掺3%CCCW、复掺3%CCCW和1%、2%及3%NS的5种混凝土试件,通过抗压强度试验、超声波探伤试验和SEM试验研究了混凝土的力学性能与不同养护龄期下(7 d、14 d、28 d、56 d)混凝土的自修复性能。结果表明,随着龄期的延长和NS掺量的增加,混凝土的抗压强度均呈现上升趋势。单掺CCCW和复掺CCCW与NS混凝土的抗压强度优于基准混凝土,且复掺情况下混凝土的抗压强度高于单掺CCCW混凝土;单掺CCCW和复掺CCCW与NS混凝土具有良好的自修复性能。随着养护龄期的延长,复掺情况下混凝土修复后抗压强度的增长趋势和波速明显优于其他混凝土;预压80%极限抗压强度的混凝土自修复效果优于预压60%的情况。其中,复掺3%CCCW与1%NS混凝土修复后的抗压强度、波速与强度恢复率均高于其他混凝土;CCCW与NS的掺入促进了裂缝处未水化水泥颗粒的水化反应,生成结晶体,从而形成致密的结晶体网络,提高了混凝土自修复性能。

In order to study the effect of cementitious capillary crystalline waterproofing(CCCW)and nano-silica(NS)on the self-healing properties of concrete,five types of concrete specimens,which were the referring group,mixed with 3%CCCW,3%CCCW and 1%NS,3%CCCW and 2%NS,3%CCCW and 3%NS,were made to test the mechanical properties of concrete and the self-healing properties of pre-compressed concrete at different curing ages(7 d,14 d,28 d,56 d)by compressive strength tests,ultrasonic flaw detection tests and SEM tests.The results show that with the extension of curing ages and the increasing proportion of NS,the compressive strength of concrete presents the trend of escalation.The compressive strength of concretes(single-doped CCCW,composite incorporating CCCW and NS)is better than the referring group,and the compressive strength mixed with composite CCCW and NS is higher than single-doped CCCW;The concrete mixed with single-doped CCCW,composite incorporating CCCW and NS have good self-healing properties.With the extension of curing age,the growth trend of compressive strength and ultrasonic velocity of concrete mixed with composite incorporating CCCW and NS after repairing are more significant than other concrete;The self-healing effect of ultimate compressive strength which is pre-compressed by 80%is better than it is pre-compressed by 60%.Among these,the compressive strength,ultrasonic velocity and strength restoration ratio of 3%CCCW and 1%NS concrete are significantly better than others;The CCCW and NS promote the hydration reaction of the unhydrated cement particles at the cracks and form crystals,thereby forming a dense crystal network and improving the self-healing properties of concrete.