HCSA膨胀剂对喷射混凝土微观结构的影响

在喷射混凝土中适量加入HCSA膨胀剂配制成喷射补偿收缩混凝土,通过X射线衍射(XRD)、扫描电子显微镜(SEM)和水泥稠凝测定仪等对喷射补偿收缩混凝土中主要胶凝材料的微观形貌、晶体结构及初凝时间等进行了测试。研究结果表明,8%HCSA膨胀剂与5%速凝剂、硅酸盐水泥形成的三元胶凝材料,具有初凝时间短、抗压强度高的特性;掺加适量HCSA膨胀剂明显促进了水化产物钙矾石和CaCO3晶体的生长,钙矾石晶体的生长填充了胶凝材料的微孔洞和缝隙,形成相互交错的网状结构,有利于提高混凝土的密实度和抗压强度。

Effects of HCSA Expansive Agent on Microstructure of Shotcrete

Shrinkage-compensating shotcrete was prepared by adding an appropriate amount of HCSA expansive agent.Micromorphology,crystal structure and initial setting time of gelled materials in shrinkage-compensating shotcrete were tested by using X-ray diffraction(XRD),scanning electron microscopy(SEM) and Vicat apparatus.The results showed that the gelled materials with short initial setting time and high compressive strength were formed by adding 8% HCSA expansive agent,5% accelerator into portland cement.Appropriate addition of HCSA expansive agent obviously promoted the growth of ettringite and CaCO3 crystals.The micro-pores and cracks of the gelled materials were filled with the grown ettringite crystals,forming interlaced net structure,which was beneficial to improving the density and compressive strength of concrete.