超细粉煤灰和偏高岭土改性水泥基透水混凝土性能研究

Study on properties of ultrafine fly ash and metakaolin modified cement-based pervious concrete

研究了单掺超细粉煤灰、偏高岭土和复掺超细粉煤灰与偏高岭土对透水混凝土浆体流动性、力学性能、透水性能的影响,并通过SEM进行微观分析。试验结果表明:超细粉煤灰能显著提高透水混凝土后期强度,但早期强度较低,其“滚珠效应”能提高水泥浆体的流动性,但会降低透水混凝土的孔隙率与透水系数;偏高岭土能改善透水混凝土的抗压强度,但会降低浆体的流动性,降低透水混凝土的孔隙率与透水系数;在掺入超细粉煤灰的同时复掺偏高岭土,能进一步增强水化反应,使浆体结构更加紧密稳定,从而提高透水混凝土的力学性能,同时能有效防止单掺超细粉煤灰引起的早期抗压强度下降。20%的超细粉煤灰与5%的偏高岭土混掺效果最佳,可以制备出抗压强度、孔隙率、透水系数分别为27.26 MPa、17.23%、2.93 mm/s的透水混凝土。

The effects of single-mixed ultrafine fly ash,metakaolin and double-mixed ultrafine fly ash and metakaolin on the fluidity,mechanical properties and water permeability of permeable concrete slurry were studied,and the microscopic analysis was carried out by SEM.The results show that the ultrafine fly ash can significantly improve the late strength of pervious concrete,but the early strength is low.Its“ball effect”can improve the fluidity of cement slurry,but will reduce the porosity and permeability coefficient of pervious concrete.Metakaolin can improve the compressive strength of permeable concrete,but it can reduce the fluidity of slurry,porosity and permeability coefficient of permeable concrete.The addition of ultrafine fly ash and metakaolin at the same time can further enhance the hydration reaction and make the slurry structure more compact and stable,thus improving the mechanical properties of permeable concrete,and effectively prevent the early compression strength decline caused by the single addition of ultrafine fly ash.The mixture of 20%ultrafine fly ash and 5%metakaolin has the best effect,and the permeable concrete with compressive strength,porosity and permeability coefficient of 27.26 MPa,17.23%and 2.93 mm/s can be prepared respectively.