碱激发高掺量玄武岩石粉砂浆的强度及微观性能研究

Study on Strength and Microscopic Properties of Alkali Activated High Dosage Basalt Powder Mortar

为提高石粉的活性和掺量,采用单掺和复掺的方式选用不同掺量的激发剂对玄武岩进行激发;对不同掺量激发剂的玄武岩石粉砂浆进行抗压、抗折实验和微观实验。结果表明:单掺激发剂中激发效果最好是掺量为0.5%的Ca(OH)2,其3d的抗压强度提高38.46%,抗折强度提高4.87%,电镜扫描得出集料-浆体截面过渡区周围及内部有大量针刺状及柱状水化硅酸钙(C-S-H)等凝胶产生;复掺激发剂水玻璃+Ca(OH)2中水玻璃掺量为1.0%激发效果最好,7d抗压强度提高24.88%,抗折强度提高5.1%,电镜扫描得出集料-浆体截面过渡区大量水化产物呈板状和柱状;未加激发剂胶砂只有水化到后期才会产生大量板状和柱状的胶凝材料,说明激发剂大大加速了水化反应,这是胶砂强度前期迅速提高的原因。

In order to improve the activity and dosage of stone powder,different dosage of activator was selected to excite basalt by single and compound mixing method;compressive,flexural and microscopic experiments were carried out on basalt powder mortar with different dosage of activator. The results show that the best excitation effect of single-mixing activator is 0.5% calcium hydroxide. The compressive strength of 3 d increases by 38.46% and the flexural strength increases by 4.87%. Scanning electron microscopy reveales that there is a large number of needling and columnar hydrated calcium silicate (C-S-H) gel around the transition zone of aggregate and paste section. The addition of activator sodium silicate+calcium hydroxide in water glass is 1.0%,and the excitation effect is the best,and the compressive strength of 7 d is raised by 24.88%,flexural strength increases by 5.1%. A large number of hydration products in the transition zone of aggregate-paste cross-section are found to be plate-like and columnar by scanning electron microscopy. No activator can produce a large number of plate-like and column-like cementitious materials only at the later stage of hydration,indicating that activator greatly accelerates the hydration reaction.This is the reason for the rapid improvement of mortar strength in the early stage.