低品质粉煤灰对再生预拌砂浆流变及物理性能影响

Effect of low-quality fly ash on the rheology and physical properties of recycled pre-mixed mortar

低品质粉煤灰(FA)因活性低、级配差等问题在工程应用推广仍困难。研究不同掺量的FA及减水剂下再生预拌砂浆(RPMs)工作流变性与物理性能。相比于内掺FA,具有双亲特性的聚羧酸类减水剂可更大幅度改善RPM的保水率(W)与2 h稠度损失率(Sp_(2 h)),更大幅度地提升RPM浆料表观密度(ρ0)与硬化体抗压强度(f_(cu)^(28))。当减水剂掺量从0.5%增至0.7%时,RPM保水率、Sp_(2 h)分别从93.1%增至94.2%,从20.2%降至13.9%;而相应ρ0、f_(cu)^(28)可分别从1951.6 kg/m^(3)增至1989.9 kg/m^(3),18.1 MPa增至21.5 MPa,达到M15等级的RPM。同步调控FA及减水剂掺量为低品质FA广泛应用于RPM各类制品提供了思路借鉴与技术支撑,具有良好的环保经济效益。

Low-quality fly ash(FA)application in engineering was still limited due to its low activity,bad gradation,etc.Here,the rheological properties and physical properties of recycled pre-mixed mortars(RPMs)with different dosages of FA and water-reducer were investigated.Compared with dosing FA,polycarboxylic water-reducer with amphiphilic properties can greatly improve the water retention rate(W)and 2 h consistency loss rate(Sp_(2 h))of RPM,and increase the slurry apparent density(ρ0)and cured compressive strength(f_(cu)^(28)).When the content of water-reducer increases from 0.5%to 0.7%,the W and Sp2 h of RPM increases from 93.1%to 94.2%,from 20.2%to 13.9%,respectively.Wherein the correspondingρ0 and f_(cu)^(28)increases from 1951.6 kg/m^(3)to 1989.9 kg/m^(3),from 18.1 MPa to 21.5 MPa,respectively,achieving to M15 grade.Simultaneously regulation on FA and water-reducer provides reference ideas and technical supports for the wide applications of low-quality FA in various products of RPM,and have good environmental and economic benefits.