硬脂酸钠对碱激发矿渣-赤泥胶凝材料吸水速率的影响

Effect of Sodium Stearate on Water Absorption Rate of Alkali-Activated Slag-Red Mud Cementitious Material

碱激发矿渣-赤泥胶凝材料(AASR)由于吸水速率较大,水分和侵蚀性离子易进入AASR内部,对其耐久性构成重大威胁。本文利用硬脂酸钠(NaSt)改善AASR的孔结构,并在孔隙壁上引入憎水膜,降低AASR的吸水速率。通过对AASR孔结构、接触角和微观形貌的分析,揭示了NaSt对AASR吸水速率的改善机理。结果表明:NaSt在AASR内部引入了较多的封闭孔,内部孔隙之间的连通性会被这些封闭气孔阻断,从而阻断水分在AASR孔径中的传输;NaSt在毛细孔壁形成憎水膜,增大了孔壁接触角,降低了毛细管吸力;掺入质量分数为0.5%的NaSt后,AASR的初始吸水速率的降低幅度高达83%,但对力学性能影响较小。

Due to alkali-activated slag-red mud cementitious material(AASR)with high water absorption rate,water and erosive ions are easily enter into AASR interior,which poses a great threat to AASR durability.Sodium stearate(NaSt)was used to improve the pore structure of AASR,and a water-repellent film was introduced on the pore wall,which reduces its water absorption rate of AASR.The improvement mechanism of NaSt on the water absorption rate of AASR was revealed by analysing of the pore structure,contact angle and micromorphology of AASR.The results shows that NaSt introduces more closed pores into AASR interior and the connectivity of the internal pores will be blocked by these closed pores,thus the water transport is blocked in the AASR pore size.A water-repellent film formed by NaSt is formed in the capillary wall,which increases the contact angle of the pore wall and reduces the capillary suction.The reduction of initial water absorption rate of AASR with adding 0.5%(mass fraction)NaSt is up to 83%,but it has less effect on mechanical properties.