脱硫石膏基无砂自流平砂浆的制备与性能研究

采用脱硫建筑石膏、P·O 42.5水泥、粉煤灰、石灰石超细粉以及外加剂为原料制备脱硫石膏基无砂自流平砂浆。采用正交试验确定石膏基胶凝材料的最优配合比,研究缓凝剂和纤维素醚对石膏基无砂自流平砂浆的性能影响,并利用XRD和SEM分别分析胶凝体系的水化产物和微观形貌,通过分析结果进一步研究外加剂的作用机理。结果表明:当脱硫石膏、水泥、粉煤灰和石灰石超细粉的质量比为16:1:2:1时,石膏基胶凝材料的强度最优;缓凝剂明显延长砂浆的凝结时间,但会导致砂浆产生泌水现象;纤维素醚可以提高砂浆的保水性,纤维素醚的引气作用造成砂浆强度下降。脱硫石膏基无砂自流平砂浆的性能指标满足《石膏基自流平砂浆》(JC/T 1023—2007)的要求。

Preparation and Performance of Desulphurized Gypsum-Based Sandless Self-Leveling Mortar

The desulphurized gypsum-based sandless self-leveling mortar was prepared by desulphurized building gypsum, P·O 42.5 cement, fly ash, limestone ultrafine powder and admixtures as raw materials. The optimal ratio of gypsum-based cementitious material was determined by orthogonal test. The effects of retarder and cellulose ether on the performance of gypsum-based sandless self-leveling mortar were studied. XRD and SEM were used to analyze the hydration products and microstructure of the system, and the mechanism of the admixtures was further studied through the analysis results. The results show that when the mass ratio of desulfurized gypsum, cement, fly ash and limestone ultrafine powder is 16:1:2:1, the strength of material is optimal. The retarder significantly prolongs the setting time of the mortar, but it causes bleeding of the mortar. Cellulose ether improves the water retention of the mortar, but the strength of mortar decreases due to the air-entraining of cellulose ether. The performance of desulfurized gypsum-based sandless self-leveling mortar meets the requirements of “Gypsum-based self-leveling mortar (JC/T 1023—2007)”.