基层用固废基胶凝材料配合比优化设计

Optimization of mix proportion design of solid waste-based cementitious material for base

为探究采用固体废弃物全部代替水泥用作公路基层胶凝材料的可能性,对不同配合比三掺料(矿渣粉(SP)、粉煤灰(FA)、脱硫石膏(FGD))与四掺料(SP,FA,FGD和钢渣粉(SS))胶砂试件进行了28 d抗压强度(R_(28))试验,分析胶凝材料水化反应机理,构建R_(28)预测模型并求解最佳配合比,根据最佳配合比制作胶砂试件与净浆试件并进行试验。结果显示:三掺料体系中单因素显著性排序为FA>SP,FA与SP存在交互作用,最佳配合比为w(SP)∶w(FA)∶w(FGD)=35∶55∶10;四掺料体系中单因素显著性排序为SP>SS>FA,交互作用显著性排序为(SP+FA)>(FA+SS)>(SP+SS),最佳配合比为w(SP)∶w(FA)∶w(SS)∶w(FGD)=43.8∶24.1∶22.5∶9.6。根据最佳配合比制作的三掺料胶砂试件R_(28)不满足规范要求,四掺料试件所有指标均满足规范要求并优于P·S·A 32.5级水泥,四掺料胶凝材料可替代水泥用于公路基层。

To explore the possibility of using solid waste instead of cement as the cementitious material for bases,the 28 d compressive tests on the mortar specimens with different mix proportions of three admixtures(slag powder(SP),fly ash(FA),and desulfurization gypsum(FDG)) and four admixtures(SP,FA,FDG,and steel slag powder) were conducted,and the mechanism of each component in the hydration reaction in three admixture and four admixture cementitious material were analyzed.Then an 28 d compressive strength R_(28) prediction model was proposed,and based on the optimal mix proportion,sand specimens and slurry specimens were made and tested.The results show that the significant effects of single factor in three admixture system is ranked as FA>SP,there is an interaction between FA and SP,and the optimal mix proportion is w(SP)∶w(FA)∶w(FGD)=35∶5∶10;The significant effects of single factor in four admixture system is ranked as SP>SS>FA,the order of significant interaction is(SP+FA)>(FA+SS)>(SP+SS),and the optimal mix proportion is w(SP)∶w(FA)∶w(SS)∶w(FGD)=43.8∶24.1∶22.5∶9.6.The R_(28) of mortar specimens made of three admixtures according to the optimal mix proportion do not meet the specification requirements.All indicators of specimens in four admixture meet the specification requirements,and are superior to P·S·A 32.5 grade cement.The four admixture cementitious materials can replace cement for bases.