石膏-水泥-碱-矿渣复合胶凝体系对石膏基自流平砂浆性能的影响

Influence of gypsum-cement-slag-alkali mixed binder systems on properties of gypsum based self-leveling mortars

研究了由石膏、水泥、矿渣和氢氧化钙组成的多元胶凝体系对石膏基自流平砂浆性能的影响,用XRD和SEM分析了胶凝体系的水化产物。结果表明,随着水泥掺量的增加,石膏-水泥二元体系自流平砂浆的保塑性降低,凝结时间缩短,强度呈先增后降的趋势,水泥掺量为胶凝材料的10%时,强度达到最大。在石膏-水泥-矿渣三元体系中,用矿渣替代水泥可进一步提高砂浆的强度,矿渣对水泥的最佳替代量为50%。在石膏-水泥-矿渣-氢氧化钙体系中,随着氢氧化钙对水泥替代量的增加,砂浆的流动度降低,凝结时间先缩短后趋于平稳,强度呈先增后降的趋势,较三元体系有进一步提高。一元体系自流平砂浆的耐水性最差,但干缩率最小。三元和四元体系自流平砂浆的耐水性更好,干燥收缩率大于一元和二元体系。矿渣具有较强的活性,在硫酸盐和碱激发的作用下,与Ca(OH)2发生反应,生成了C-H-S凝胶和钙矾石。

The Influence of gypsum-cement-slag-alkali mixed binder systems on gypsum based self-leveling mortar is studied.The hydrated products and microstructures are characterized by XRD and SEM.The results show that with the increase of cement content,the plasticity of gypsum-cement binary systems self-leveling mortar decreases,the setting time shortens,and the strength increases first and then decreases,reaching the maximum when the cement content is 10%of the cementitious material.In the gypsum-cement-slag ternary systems,the strength of mortar is further improved by replacing cement with slag,and the best substitution amount of slag for cement is 50%.In the gypsum-cement-slagalkali systems,with the increase of Ca(OH)2 substitution for cement,the fluidity of mortar decreases,the setting time first shortens and then tends to be stable,and the strength increases first and then decreases,which is further improved compared with the ternary system.The water resistance of single system is the lowest,but the dry shrinkage is the least.The water resistance of ternary and quaternary systems is better,but the dry shrinkage is higher.The slag has strong activity,and generates C-S-H and AFt by reacting with Ca(OH)2 under the activating of sulfate and alkali.