碱矿渣-粉煤灰砂浆的耐高温性能及孔结构研究

Study on High Temperature Resistance and Pore Structure of Alkali Slag-Fly Ash Mortar

研究了不同粉煤灰掺量的碱矿渣-粉煤灰砂浆在20℃、200℃、400℃、600℃、800℃下力学性能的变化规律,并通过X射线衍射(XRD)、红外光谱(FTIR)和压汞法(MIP)分析了浆体的水化及孔结构。结果表明:掺粉煤灰可优化浆体的孔径分布,降低内部孔隙率,提高砂浆的耐高温性能,粉煤灰的适宜掺量为30%~50%;200℃时,掺30%粉煤灰砂浆的抗压强度最高,较20℃时提高了49.3%;600℃时,发生了固相反应,C-S-H凝胶减少,少害孔(20~50 nm)数量增加,砂浆保持了与20℃相当的抗压强度;800℃时,浆体生成大量钙黄长石,砂浆的抗压强度为20℃时的11.5%,基本失去工作性能。综合考虑,碱矿渣-粉煤灰砂浆的使用温度不宜超过600℃。

The mechanical properties of alkali slag-fly ash mortar with different fly ash content at 20℃,200℃,400℃,600℃,800℃were studied,and the hydration and pore structure were examined by using XRD,FTIR and MIP.The results show that adding fly ash can optimize the pore size distribution of the slurry,reduce the internal porosity,and improve the high-temperature resistance of the mortar,and the suitable blending amount is 30%~50%.At 200℃,the compressive strength of 30%fly ash mortar is the highest,which is 49.3%higher than that at 20℃.At 600℃,the mortar maintains the same compressive strength as 20℃,but the solid phase reaction occurs in the slurry,the number of less harmful pores(20~50 nm)increases and the C-S-H decreases.At 800℃,a large amount of calcium feldspar is formed in the slurry,and the compressive strength of the mortar is 11.5%of that at 20℃,which basically loses the working performance.Comprehensive consideration,the use temperature of alkali slag-fly ash mortar should not exceed 600℃.