碱激发剂和养护条件对废弃混凝土地聚强度的影响研究

Study on the Effect of Alkali Activator and Curing Conditions on the Strength of Waste Concrete-Based Geopolymer

采用废弃混凝土粉末为原料制备地聚合物,研究氢氧化钠溶液浓度、水玻璃掺量、碱激发剂与废弃混凝土粉末质量比和养护条件(养护温度、养护时间、养护方式和龄期)对废弃混凝土地聚合物无侧限抗压强度的影响。结果表明:增大氢氧化钠溶液浓度、水玻璃掺量和碱激发剂与废弃混凝土粉末质量比均可以改善废弃混凝土地聚合物的无侧限抗压强度。当氢氧化钠溶液浓度为14 mol/L,水玻璃与氢氧化钠溶液质量比为1.5,且碱激发剂与废弃混凝土粉末质量比为0.4时,废弃混凝土地聚合物经过70℃密封养护24 h,7 d龄期无侧限抗压强度达到14.32 MPa。废弃混凝土粉末地聚合反应活性低和钙含量高是造成废弃混凝土地聚合物强度不高的原因。

The waste concrete powder was utilized as source material to prepare geopolymer.The effect of NaOH solution concentration,water glass content,mass ratio of alkali activator to waste concretepowder,and curing condition(curing temperature,curing time,curing method and age) on the unconfined compressive strength of waste concrete-based geopolymer were studied.The results indicate that increasing the NaOH solution concentration,water glass content and mass ratio of alkali activator to waste concretepowder were all leading to enhance the unconfined compressive strength of waste concrete-based geopolymer.The optimum NaOH solution concentration corresponded to 14 mol/L,water glass to NaOH solution mass ratio of 1.5 and alkali activator to waste concretepowdermass ratio of 0.4.A maximum 7-day unconfined compressive strength of 14.32 MPa was achieved by sealing curing at 70 ℃ for 24 hours.The low activity and high calcium content are the causes for the low strength of waste concrete-based geopolymer.