硅灰-粉煤灰-废石粉对透水混凝土性能的影响

Effect of silica fume-fly ash-waste stone powder on permeable concrete

采用硅灰、粉煤灰、废石粉单掺及三元复合等质量代替部分水泥,研究其对透水混凝土力学性能、透水系数及砂浆流动性的影响。结果表明:随着硅灰掺量增加,砂浆流动度先增加后减小,透水混凝土强度逐渐增大,透水系数先减小后增大,当硅灰掺量超过6%时,强度不再增加,透水系数增大,砂浆流动度下降;随着粉煤灰掺量的增加,砂浆流动度不断增加,透水混凝土强度与透水系数不断降低,单掺粉煤灰时,掺量不宜超过10%;随着废石粉掺量的增加,透水混凝土的抗压强度先增加后减少,透水系数一直减小,在掺量为15%时强度最高。硅灰-粉煤灰-废石粉三元复合体系中,掺6%硅灰、10%粉煤灰、10%废石粉的透水混凝土,砂浆流动度为162 mm,28 d强度达到38.4 MPa,透水系数达到4.4 mm/s。SEM分析发现,三元复合体系主要水化产物有水化硅酸钙凝胶和板状氢氧化钙,还有少量针状钙矾石,各水化产物之间连接较好,浆体密实,水化产物发育较好,浆体水化较完全。

Silica fume,fly ash,waste stone powder single admixture and ternary composite are used to replace part of the cement,to study its effect on the mechanical properties,permeability coefficient and fluidity of mortar of pervious concrete.The results show that with the increase of silica fume content,the fluidity of mortar increases first and then decreases.The strength of pervious concrete increases gradually,the permeability coefficient decrea-ses first and then increases.When the amount of silica fume exceeds 6%,the strength no longer increases.The permeability coefficient increases and the mortar fluidity decreases.With the increase of the amount of fly ash,the fluidity of the mortar increases continuously,and the strength and permeability coefficient of the permeable concrete are continuously reduced.When the fly ash is used alone,the dosage should not exceed 10%.With the increase of the amount of waste stone powder,the compressive strength of the permeable concrete increases first and then decreases,the water permeability coefficient decreases.The strength is the highest when the dosage is 15%.In the ternary composite system of silica fume,fly ash and waste stone powder,the mortar fluidity will be 162 mm when the permeable concrete mixed with 6%silica fume,10%fly ash and 10%waste stone powder.The 28 d strength is 38.4 MPa,and the water permeability coefficient is 4.4 mm/s.SEM analysis found that the main hydration products of the ternary composite system are hydrated calcium silicate gel and platy calcium hydroxide,and a small amount of acicular ettringite.The hydration products are well connected and the slurry is dense.The hydration products develop well,and the hydration of slurry is relatively complete,which plays a synergistic role.