基于正交设计大掺量矿渣水泥制备混凝土的力学性能及耐久性研究

摘要

Orthogonal design method with three-level and three-factor and ternary linear regression analysis are adopted to adjust the dosage of clinker,gypsum powder and coagulant,which can reduce the experimentation and work out the regression equation of the indi-cator on compressive strength at 28 d and the optimal mixture ratio of composite cementitious materials.C40 concrete are prepared by the composite cementitious materials under normal temperature curing to test its workability,compressive strength and sulfate attack resis-tance.The results show that through F test,the significant of regression equation is good.The most important factor on 28 d compressive strength of cement with large quantity of slag (SC)is the dosage of clinker and 28 d compressive strength of paste can be predicted through the regression equation.Workability of concrete is very good,and the slump is about 210 mm,slump flow is about 510 mm,the u-nit weight is about 2 410 kg/m3 which all increase with the increase of SC content.Setting times of all samples are very long,and have a decreasing trend with the increase of SC.It′s good for the transportation and casting of concrete with longer initial setting time.The concrete strength at early age (3 d)is low,while it grows rapidly at late age(7~28 d).With the increase of SC,corrosion resistance coefficients in-crease gradually and remain above 1.0,which indicates that SC has strong ability to resist sulphate erosion.%通过调整熟料、石膏粉和促凝剂的用量,采用三因素三水平正交设计方法及三元一次回归分析,在减少试验量的同时,得出以28 d抗压强度为考察指标的回归方程,得出最优配合比制备复合胶凝材料.采用此复合胶凝材料制备C40混凝土,在常温养护下考察其工作性、抗压强度及抗硫酸盐侵蚀能力.结果表明:回归方程经过F检验,显著性良好;影响大掺量矿渣水泥28 d抗压强度最主要因素是熟料掺量,且可通过回归方程可对净浆水泥28 d抗压强度作定量预测;C40混凝土具有较好的工作性,坍落度在210 mm左右,扩展度在510 mm左右,表观密度在2410 kg/m3左右,基本均是随着大掺量矿渣水泥掺量的增加而增大;各试样凝结时间均较长,且随着大掺量矿渣水泥掺量的增加有减小趋势,初凝时间较长利于混凝土的运输与浇筑;混凝土早期(3 d龄期)强度稍低,后期(7~28 d)强度增长较快;随着大掺量矿渣水泥掺量的增加,抗侵蚀系数基本逐渐增加,且均保持在1.0以上,具有较强的抗侵蚀能力.