可喷射超高韧性水泥基复合材料抗氯离子渗透性能研究

Chloride ion penetration resistance of sprayable ultra high toughness cementitious composites

利用RCM法对基于高贝利特硫铝酸盐水泥制备的可喷射超高韧性水泥基复合材料(UHTCC)的抗氯离子渗透性能进行了一系列的试验,研究了纤维规格、成型工艺、养护龄期及粉煤灰掺量对UHTCC抗氯离子渗透性能的影响。结果表明:PVA纤维的可显著改善脆性水泥基体的抗氯离子渗透性能,其中12 mm PVA纤维的改善效果优于8 mm PVA纤维,PVA纤维长度12 mm、体积掺量为2%时,可喷射UHTCC的28 d氯离子迁移系数仅为2.05×10^(-12) m^(2)/s;随龄期延长,伴随水泥水化、粉煤灰及硅粉火山灰反应的持续进行,UHTCC的氯离子迁移系数逐渐减小;尤其是在高贝利硫铝酸盐水泥具有较高硅酸二钙含量的情况下,制备的可喷射UHTCC长龄期抗氯离子渗透性能仍有较大提升空间。

In this paper,the RCM method was used to conduct a series of experiments on the chloride ion penetration resistance of ultra high toughness cementitious composites(UHTCC).The effects of fiber type,molding process,curing age and the content of fly ash on the chloride penetration resistance of UHTCC were investigated.The test results showed that:The application of PVA fiber could significantly promote the chloride ion penetration resistance of brittle cementitious matrix,and the improvement effect of 12 mm-long PVA fiber was better than that of 8 mm-long fiber.When the PVA fiber length is 12 mm and the volume dosage is 2%,the chloride ion migration coefficient of sprayable UHTCC developed at 28 days is only 2.05×10^(-12) m^(2)/s;With the increasing of curing age,the continuous cement hydration and pozzolanic reaction of fly ash and silica fume would further lower the chloride ion migration coefficient of UHTCC especially with the use of high belite sulphoaluminate cement,and there is still room to improve the long term chloride penetration resistance of the prepared sprayable UHTCC.