复掺外加剂体系对低水胶比混凝土强度及耐久性影响试验研究

摘要

对低水胶比(mW/mB=0.3)复掺外加剂体系(膨胀剂、减水剂、引气剂)拌制的混凝土进行强度及耐久性正交试验,分析了不同掺量对新拌混凝土工作性、混凝土强度及耐久性的影响规律,基于电通量法和快速氯离子迁移系数法(RCM法)评定混凝土的耐久性,给出各外加剂的最优掺量.结果表明:外加剂复掺体系所引起的电通量及氯离子迁移系数变化趋势相近,耐久性变化均随着外加剂掺量的增加先变好后变差,在此配合比下,JS=1.5%,YQ=0.4%,PZ=8%时混凝土耐久性最好;3种外加剂对混凝土的强度增长均有促进的作用,其中减水剂对混凝土早期强度和后期强度影响最明显;随着引气剂掺量的增加,强度先降低后增加;膨胀剂掺量对混凝土强度影响无固定规律.鉴于试验选用地材及配合比等的局限性,本研究仅为后续类似研究提供参考.%The orthogonal experiment of strength and durability of one low water-binder ratio(mW/mB =0.3) concrete was done in the circumstance of different dosage of compound admixture system(expansive agent,water reducing agent,air-entraining agent).The influences of workability of concrete,concrete strength and durabil-ity changed with different dosage were analyzed.The durability of the concrete was assessed based on the electric flux method and the rapid chloride ion migration coefficient method (RCM method),and the optimal dosage of different admixtures was obtained.Results show that the change regulation of electric flux and the rapid chloride ion migration coefficient is familiar.The durability of change both increases with the increase of dosage of admix-ture variation,good first and then bad,under the mixture ratio,the dosage of J =1 .5%,Y =0.4%,P =8%has the best performance on the permeability in concrete;Three kinds of admixture have a promoting role on the strength growth of concrete,including water reducing agent is most evident influence on the early and the late strength of concrete;With the dosage increase of air-entraining agent,the strength decreases and then increa-ses;The dosage of expansive agent has no fixed effect on concrete strength.The incorporation of mineral admix-tures is advantageous to the durability of the concrete.Given the selection of mixture ratio and ground material limitations,this study only provide reference for subsequent similar studies.