粉煤灰对砂浆力学性能与孔结构参数的影响

Effect of fly ash on mechanical properties and pore structure parameters of mortar

贵州II级粉煤灰排放量多且分布广。为了明确各地区II级粉煤灰的差异性及对砂浆力学性能和孔结构参数的影响,采用都匀粉煤灰、大方粉煤灰、鸭溪粉煤灰和六盘水粉煤灰等质量替代水泥,探讨粉煤灰掺量对砂浆力学性能、吸水量和孔结构参数的影响,并分析其作用机理。结果表明:粉煤灰的掺入显著降低砂浆的抗折强度和抗压强度,掺量以20%为宜,但抗折强度与抗压强度之比不断增长,抗折强度为抗压强度的1/4~1/5.8。粉煤灰种类和掺量对砂浆吸水量、孔径均匀性和平均孔径的影响规律不同,但粉煤灰砂浆的吸水量高于纯水泥砂浆。粉煤灰在砂浆中的作用可简述为形态作用、填充作用和火山灰效应,文中4种II级粉煤灰的活性较低,在砂浆中主要以填充作用为主。

II grade fly ash emissions in Guizhou is in wide distribution. In order to define the difference and the influence of II grade fly ash on the mechanical performance and pore structure parameters of mortar,we apply Duyun fly ash,Dafang fly ash,Yaxi fly ash and Liupanshui fly ash replace quality cement to explore the effect of fly ash dosage on the mechanical properties,water absorption and pore structure parameters of mortar and analyze its mechanism. Results showed that the flexural strength and compressive strength of mortar was significantly low with fly ash addition,the best replacement rate was 20% for4 kinds of fly ash,but the ratio of the flexural strength and compressive strength were growing and the flexural strength was 1/4 - 1/5. 8 for compressive strength of mortar. The influence law of type and dosage of fly ash on water absorbing capacity,pore size uniformity and average pore diameter was different,and the water absorbing capacity of fly ash mortar was higher than the pure cement mortar. The role of fly ash in mortar cowd be briefly for shape function filling effect and pozzolanic effect,the activity of 4 kinds of II grade fly ash in this paper was low,which were mainly filling effect in the mortar.