HPMC对铝酸盐水泥-石膏二元胶凝体系砂浆性能的影响

Effect of Hydroxypropyl Methyl Cellulose on Aluminate Cement‑Gypsum Mortar

研究了羟丙基甲基纤维素(HPMC)及其掺量对铝酸盐水泥-石膏二元胶凝体系砂浆物理力学性能的影响,并采用压汞仪和扫描电镜对砂浆宏观性能的变化作出了合理解释.结果表明:HPMC会大幅度改变砂浆的保水率、含气量、凝结时间、流动度、稠度值和体积密度,明显提高新拌砂浆的可塑性,增加可操作时间,但却会降低硬化砂浆的抗折强度、抗压强度和拉伸黏结强度;硬化砂浆强度的降低归因于HPMC会大幅度增加砂浆孔隙率和孔尺寸,并改变水化产物形态.因而在实际应用中,应慎重考虑使用HPMC来改性铝酸盐水泥-石膏二元胶凝体系砂浆的两面性.

The effect of hydroxypropyl methyl cellulose(HPMC)and its content on the physical and mechanical properties of aluminate cement gypsum mortar was investigated.The results obtained by mercury intrusion porosimetry(MIP)and scanning electron microscopy(SEM)were used to make a reasonable explanation for the change of macro properties.The results show that HPMC can affect the water‑retention rate,air content,setting time,flow,consistency and wet density which play a key role in increasing the plasticity and operational time of the fresh mortar.HPMC reduces the flexural strength,compressive strength,and tensile bond strength of the hardened mortar.The decrease of the strength is due to the fact that the HPMC increases the porosity and pore volume and changes the distribution of hydration products.Therefore,in practical application,the two sides of the HPMC modified aluminate cement‑gypsum mortar should be considered carefully.