Na2SO4激发低水胶比粉煤灰-水泥砂浆力学性能研究

Mechanical Performance of Na2SO4 Activated Fly Ash-Cement Mortar at Low Water-Binder Ratio

固定水胶比为0.24,通过I级粉煤灰替代砂浆中30%~70%水泥的强度试验,研究了Na 2 SO 4对粉煤灰-水泥砂浆体系的激发效果。结果表明:不掺激发剂时,砂浆抗压和抗折强度随粉煤灰替代率的增加成比例下降,且粉煤灰替代率达50%以上时对强度增长速率有显著提升作用。粉煤灰替代率不低于50%时,1%的Na 2 SO 4掺量对砂浆抗压强度增进效果最佳,与此不同的是,Na 2 SO 4掺量越高,对砂浆抗折强度的增长越有利。随龄期增长,Na 2 SO 4激发粉煤灰-水泥砂浆的折压比显著下降,但抗折强度均在5.0 MPa以上。

An experimental investigation on the effect of fly ash and Na 2SO 4 content on compressive strength,flexural strength of fly ash-cement mortar was presented.Class I fly ash was used to partially replace portland cement by weight varied between 30%and 70%.The water binder ratio of 0.24 was used for all the mortars.Test results indicate that when no Na 2SO 4 is mixed,the compressive and flexural strength are reversely proportional to the fly ash replacement ratio,but the development ratio of the strengths are significantly increased by the replacement ratio of fly ash over 50%.When the fly ash replacement ratio is not less than 50%,it increases compressive strength,and the optimum content is 1%by weight.In contrast,increasing the Na 2 SO 4 content is beneficial to the increase of flexural strength.The ratio of flexural to compressive strength is significantly decrease with the changing age of concrete,yet the flexural strength of fly ash-cement mortar are all over 5.0 MPa.