氯盐环境下铁路混凝土配合比参数的研究

分析氯离子扩散系数作为氯盐环境下混凝土耐久性评价指标的原因及合理性。系统研究水胶比(0.33、0.38、0.45)、矿物掺和料种类(粉煤灰、磨细矿渣粉、偏高岭土、硅灰)、掺量及含气量等配合比参数对混凝土氯离子渗透性能影响规律;探讨氯盐环境下铁路混凝土配制要求;提出氯盐环境下铁路混凝土配合比参数限值。研究表明:氯盐环境下适当加入矿物掺和料是提高混凝土耐久性的关键技术措施;粉煤灰和矿渣适宜掺量分别为30%～50%、40%～60%;适当引气(含气量为4%～6%)能提高混凝土抗氯离子渗透性能;严重氯盐腐蚀环境下,应采用矿物掺和料复掺技术,且宜添加适量硅灰。

Mixture Ratio of Railway Concrete under Chloride Environment

The reason and rationality of taking the chloride diffusion coefficient as the durability evaluation index of concrete used in the chloride environment was analyzed.The law of the effects of the mixture ratio parameters such as the ratio between water and binder(0.33,0.38,0.45),type and dosage of mineral admixtures(fly ash,grounded fumace slag powder,flour ash,metakaolin,silica fume) and air content on chlorion impermeability in concrete was studied.The requirements for mixing concrete under the chloride environment for railways were discussed and the corresponding limit of mixture ratio was put forward.The results show as follows: Appropriate addition of mineral admixtures is an effective key method to improve the durability of concrete under the chloride environment;the proper adding dosages of fly ash and slag are 30%~50% and 40%~60% respectively;chlorion impermeability of concrete can be improved the entraining technology and the optimum air content is 4%~6%;under the severely chloride-corrosive environment,the composite mixing technique of mineral admixtures should be adopted and the appropriate amount of silica fume should be added.