粉煤灰-矿粉-水泥胶凝体系的高效复合早强剂研制

摘要

The strength enhancing efficiency and mechanism of five kinds of strength accelerator in cement containing fly ash and ground granulated blast-furnace slag were compared, then the optimum compositions were developed by means of progressing composition with them. Further researches were carried out about the effects of three kinds of retarder on the strength accelerating efficiency of those optium compositions. In the end, a high performance composite strength accelerator was developed. The results indicate that there exists obvious additive strength accelerating effects among triethanolamine, inorganic salt A, sodium formate and calcium chloride, which will accelerate the hydration of C3A and C3S in the cementing system, but the additive hydration accelerating effects on C3 A will influence their inherent acceleration for the hydration of C3S and consequently have adverse function to the development of later age strength of the system. Such retarders as sucrose, sodium tripolyphosphate, organic acid B can efficiently reduce the acceleration effects of hydration of C3 A from the former composite strength accelerators and enhance the hydration of C3S, which can make the composite strength accelerator act nearly in a balanced state. The final formula of the high performance composite strength accelerator obtained from the research is: triethanolamine 0. 02% + inorganic salt A 0. 06%+ sodium formate 0. 06% + organic acid B 0. 01%, the mixing' content accounts for 0. 15% of the total cementing materials. It can improve 3 d compressive strength78. 3% and 7 d compressive strength 46. 1% with little change of fluidity and setting time.%以粉煤灰-矿粉-水泥胶凝体系为对象,比较5种早强组分的早强特性和作用机制后,通过递进式叠加优化获得早强组分最佳复配方案,进而分别研究3种缓凝组分对其早强性能的影响,以获得最终的高效复合早强剂组成方案.研究表明:早强组分三乙醇胺、无机盐A、甲酸钠、氯化钙之间存在良好的叠加增强效应,可有效促进胶凝体系C3A和C3S的水化,但对C3A水化的叠加促进作用会影响其对C3S水化固有促进作用的发挥,不利于体系后期强度的发展;蔗糖、三聚磷酸钠、有机酸B这3种缓凝组分可有效缓解复合早强组分对C3A水化的过度促进,增强C3S水化,使复合早强剂的增强性能更为均衡.最终确定的高效复合早强剂组成方案为:三乙醇胺0.02％(质量分数,下同)+无机盐A 0.06％+甲酸钠0.06％+有机酸B 0.01％,掺量为胶凝材料总量的0.15％,采用该方案可使胶凝体系3d抗压强度提高78.3％,7d抗压强度提高46.1％,流动度和凝结时间则变化不大.