不同化学激发剂对再生微粉活性的影响及机理研究

Effects and Mechanism Research of Different Chemical Activators on Activity of Recycled Fine Powder

再生微粉由于活性较低,难以被有效利用,造成极大的资源浪费。为激发再生微粉的活性,本文研究了四种传统碱激发剂(氢氧化钠、氢氧化钙、氢氧化镁、水玻璃)、两种醇胺类激发剂(多元异构醇胺、三乙醇胺)和一种纳米晶核型激发剂对掺再生微粉砂浆抗压强度的影响,并通过分析化学激发剂对再生微粉-水泥浆体水化放热、水化产物及微观结构的影响揭示其提升机理。结果表明:氢氧化钠和水玻璃会导致掺再生微粉砂浆的抗压强度进一步降低,且砂浆强度与氢氧化钠和水玻璃的掺量成反比;氢氧化钙、氢氧化镁、三乙醇胺和纳米晶核型激发剂在一定掺量条件下可以提高早期强度,但无法提高后期强度;多元异构醇胺激发剂的掺入明显促进了矿物相铝酸三钙(C_(3)A)与铁铝酸四钙(C_(4)AF)的水化,从而加快再生微粉-水泥浆体的水化进程,提高水泥基体的密实度并改善水泥基体与砂的界面黏结情况,使砂浆各龄期抗压强度明显提高,在最佳掺量0.2%(质量分数)时再生微粉的活性指数由62.8%提升至74.8%。研究成果可为提高再生微粉的利用率从而实现建筑行业节能减排目标提供借鉴和参考。

Recycled fine powder(RFP)is difficult to be effectively utilized due to its low activity,resulting in a great waste of resources.To stimulate the activity of RFP,the effects of traditional alkali activators(sodium hydroxide,calcium hydroxide,magnesium hydroxide,sodium silicate),alcohol amine activators(polyisomeric alcoholic amine,triethanolamine)and nanocrystalline nuclear activator on the compressive strength of mortars mixed with RFP were investigated.Meanwhile,the effects of chemical activators on the hydration heat release,hydration products and microstructure of RFP-cement pastes were analyzed to reveal their promotion mechanism.The results show that sodium hydroxide and sodium silicate can further reduce the compressive strength of mortars mixed with RFP,and the relationships are linear inverse with their dosage.Calcium hydroxide,magnesium hydroxide,triethanolamine and nanocrystalline nuclear activator can improve the early strength under certain dosage conditions,but can not improve the later strength.Polyisomeric alcoholic amine can significantly improve the compressive strength of each age through promoting the hydration of mineral phases tricalcium aluminate(C_(3) A)and tetracalcium aluminoferrite(C_(4) AF),accelerating the hydration process of RFP-cement pastes,improving the compactness of the interfacial bond between cement matrix and sand.The activity index of RFP increases from 62.8%to 74.8%at the optimal dosage of 0.2%(mass fraction).The research results can provide reference for improving the utilization rate of RFP and achieving the goal of energy conservation and emission reduction in the construction industry.