MgO对水泥-粉煤灰胶凝材料膨胀及微观性能的影响

Influence of MgO on expansion and microscopic properties of cement-fly ash cementitious materials

采用中热硅酸盐水泥、粉煤灰、氧化镁膨胀剂制备水泥-粉煤灰微膨胀胶凝材料,研究MgO膨胀剂对浆体初始流动度、膨胀效能、孔结构和微观结构的影响。结果表明:浆体初始流动度随膨胀剂掺量增加而减小;在相同养护龄期下,膨胀率随膨胀剂掺量增加而增大;在相同掺量下,膨胀率随着养护龄期的延长而增大;加入粉煤灰后会抑制MgO膨胀剂的微膨胀性能。MgO膨胀剂掺量为7%时,孔径及孔隙率最小,且随着MgO水化的进行,孔隙中的Mg(OH)_(2)数量不断增多,结构更加致密。

This paper used medium-heat silicate cement,fly ash,MgO expander to prepare cement-fly ash micro-expansion cementitious material,to study the effect of expander on the initial flow,expansion efficiency,pore structure and microstructure of the slurry.The results showed that:the initial flow of the slurry decreased with the increase of the admixture of the expander;the expansion rate of the slurry increased with the increase of the admixture of the expander at the same curing age;the expansion rate of the slurry increased with the increase of the curing age at the same admixture;the addition of fly ash suppressed the micro-expansion performance of the MgO expander.The pore diameter and porosity of the slurry was the smallest at 7%admixture of the MgO expander,and with the hydration of the MgO,the number of Mg(OH)_(2) in the pores of the slurry keeps increasing,and the structure is more dense.