【作者】 张云升； 孙伟； 陈树东； 郭飞；

【Author】 Zhang Yunsheng Sun Wei Chen Shudong Guo Fei (Jiangsu Key Laboratory of Civil Engineering Materials, Southeast University, Nanjing 211189, China)

【机构】 东南大学江苏省土木工程材料重点实验室；

【摘要】 首先建立了弯拉应力作用下混凝土的多维碳化测试方法,在此基础上系统研究了粉煤灰混凝土在弯拉应力水平分别为0,0．20,0．35,0．50,0．65,0．80作用下多维碳化深度的依时变化规律．探讨了粉煤灰掺量(0％、10％、20％、40％、60％)、粉煤灰种类(Ⅰ级、Ⅱ级)、水胶比(0．3、0．35、 0．4)、胶凝材料用量(458,380 kg／m3)、养护龄期(28,90 d)五个重要因素对处于弯曲应力状态下的粉煤灰混凝土多维碳化深度的影响规律．另外,还将不同弯拉应力水平(σs)下的碳化实验结果与同条件下无应力状态下的碳化进行了定量比较,发现弯拉应力水平对碳化存在明显的加速作用,为量化该交互作用提出了应力加速因子(Kσs)概念,研究表明Kσs随σs的增加而变大,符合指数函数 Kσs=1+k(σs)c．最后,还初步建立了综合考虑应力、碳化维数、养护龄期、粉煤灰种类及掺量、水胶比和胶结材用量等重要影响因素的多因素碳化寿命预测模型．上述研究以期为准确预测实际混凝土结构在真实状态下碳化寿命提供科学依据．更多还原

【Abstract】 A method used to measure the multi-dimensional carbonation depth of concrete under flexural stress is developed in this paper. Using this method, multi-dimensional stress carbonation depth at different carbonation age were systematically investigated for fly ash concretes made with different cement replacement percentage by fly ash (0% , 10% , 20% , 40% , 60%), types of fly ash (grade Ⅰ,Ⅱ), water to binder ratios (0. 3, 0. 35, 0. 4), amount of binders (458,380kg/m3), and curing ages (28, 90 d). In addition, a comparison was made between stress-carbonation testing results and no stress-carbonation ones. A carbonation accelerating effect caused by external flexural stress can obviously be observed through the comparison. In order to quantify the stress accelerating effect, stress accelerating factor (Kσs) is proposed in this paper. Finally, the relationship between Kσs and σs(external stress-to-ultimate stress ratio) is given as exponential function Kσs=1+k(σs)c. A new carbonation prediction model of fly ash concrete is established based on considering the effects of stress ratios, fly ash types and content, water to binder ratios, curing ages, and binder amount. The above research provides an insight into carbonation attack on the edge reinforcing bars of concrete structures under flexural stress, such as large-span beam and board in the field of civil engineering.更多还原