摘要
碳化是影响混凝土结构耐久性的重要因素。为掌握桥梁大体积混凝土工程用的大掺量矿物掺合料混凝土的抗碳化性能,通过加速碳化试验,研究了水胶比、矿物掺合料掺量及复合掺合料中粉煤灰与矿粉掺入比对混凝土碳化深度的影响,基于气体扩散理论碳化模型并考虑碳化残量,对大掺量矿物掺合料混凝土桥梁结构的碳化寿命进行预测。结果表明:当矿物掺合料掺量大于40%后,随着掺合料掺量的增大,混凝土抗碳化能力下降;与单掺粉煤灰相比,粉煤灰与矿粉复掺可以减轻大掺量矿物掺合料混凝土抗碳化性能的降低;降低水胶比、提高复合掺合料中矿粉的掺入比,可以显著提高大掺量矿物掺合料混凝土的抗碳化能力。大体积承台、锚碇结构采用大掺量矿物掺合料混凝土,可以完全保证100年以上的寿命。
Carbonation is an important factor that affects the durability of concrete structures.In order to grasp the carbonation resistance ofconcrete with large amount of mineral admixture which is applied in the mass concrete project for bridge,by accelerating carbonization test,this paper studied the influence of water/binder ratio,dosage of mineral admixtures and the mixing ratio of fly ash and slag powder in composite mineral admixtures on the carbonation depth of concrete.Based on the theory model of gas diffusion and considering the carbonization residual amount,the carbonation life of the bridge concrete structures with large amount of mineral admixtures is predicted.The results show that when the content of the mineral admixture is more than 40%,the carbonation resistance of concrete decreases with the increase of the content of mineral admixtures.Compared with single fly ash,the composite admixtures of fly ash and slag powder can alleviate the decline of carbonation resistance of the concrete with large amount of mineral admixtures.By reducing the water/binder ratio and increasing the mixing ratio of slag powder in the composite admixtures,the carbonation resistance of concrete with large mineral admixtures content can be significantly improved.The large volume cap and anchorage structures,which adopts the concrete with large amount of mineral admixtures,can completely guarantee the carbonation life of more than 100 years.
作者
徐小华
董长征
魏鑫
李北星
XU Xiaohua;DONG Changzheng;WEI Xin;LI Beixing(Hubei Province Chibi Yangtze River Highway Bridge Co.,Ltd.,Chibi 437300,China;State Key Laboratory of Silicate Materials for Architectures,Wuhan University of Technology,Wuhan 430070,China)
出处
《粉煤灰综合利用》
CAS
2021年第4期59-63,76,共6页
Fly Ash Comprehensive Utilization
基金
国家自然科学基金项目(51372185)。
关键词
桥梁工程
大体积混凝土
矿物掺合料
碳化
寿命预测
bridge engineering
mass concrete
mineral admixture
carbonation
service life prediction
