A new type of retarder, of which main ingredients are boracic acid and aluminum sulphate, was developed for sulphoaluminate cement. The influence of the new type of retarder and aluminum sulphate on the retarding effect and the mechanical property of sulphoaluminate cement was analyzed by SEM. Experimental results show that adding 0.3％ mass fraction of boracic acid, the initial setting time of sulphoaluminate cement is 296 min ,and the final setting time is 361 min;adding 0.3％ mass fraction of boracic acid and 0.5％ mass fraction of aluminum sulphate,the initial setting time and the final setting time reduce to 113 min and 168 min;continuing to increase the mass of aluminum sulphate will further reduce the setting time without negative effects on the early strength and increase the later strength. Aluminum sulphate can accelerate the set of sulphoaluminate cement, but slightly decrease the compressive strength.%复掺硼酸和硫酸铝研制新型硫铝酸盐水泥缓凝剂.采用扫描电子显微镜(SEM)分析新型缓凝剂和硫酸铝对硫铝酸盐水泥的缓凝效果和力学性能的影响.结果表明:掺入w=0.3%的硼酸,硫铝酸盐水泥初凝时间为296 min,终凝时间为361 min;复掺w(硼酸)=0.3%, w(硫酸铝)=0.5%,初凝和终凝时间降为113 min和168 min,继续增加硫酸铝掺量,凝结时间会进一步降低,对前期强度无不利影响,且后期强度升高.单掺硫酸铝对硫铝酸盐水泥有促凝作用,但强度略有下降.
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