摘要
通过进行实验室模拟快速冻融试验,研究了冻融和侵蚀溶液交替作用下,持续承载钢筋混凝土梁力学性能劣化的机理,侵蚀溶液由质量百分比为3%氯化钠和0.34%硫酸镁混合而成。试验研究了经过300次冻融循环和侵蚀溶液浸泡交替作用后,不同持续荷载对钢筋混凝土梁承载力的影响,并分别用扫描电子显微镜(SEM)和X射线衍射仪(XRD)测试和分析了梁体混凝土的水化产物及显微结构。试验和测试分析结果表明:在冻融循环与侵蚀溶液浸泡的交替作用下,随着持续荷载水平提高,混凝土内部微裂缝扩展和盐类结晶愈发明显,混凝土中盐类产物也明显增加,钢筋锈蚀程度加重,导致梁的极限承载能力显著降低。可见,持续荷载对冻融循环与侵蚀溶液作用下混凝土和钢筋的劣化起到加速的作用,即持续荷载越高,钢筋混凝土梁的极限承载力降低幅度越大。
Experiments have been performed to investigate the deterioration mechanism of reinforced concrete beams with sustained-loading,under alternative actions of freeze-thaw circles and mix-aggressive solution,which are mixed solution in mass percentage of 3% NaCl(sodium chloride) and 0.34% MgSO4(magnesium sulfate).The ultimate bearing capacities of the beams sustained different loading level were tested,and the hydration product and microstructure of the concrete in the beams were investigated with SEM(scanning electron microscope) and XRD(X radial diffraction).The testing results indicated that as the sustained loading increases,under the alternative actions of freeze-thaw circles and mix-aggressive solution,micro-cracks developments and salt crystals in concrete appear more obviously,and also more salt products,which finally lead to the steel bars rusting and the bearing capacities of the beams decreasing.Obviously,under the alternative actions of mix-aggressive solution and freeze-thaw circles,mechanical performance deterioration of the concrete and steel bars are accelerated by the sustained loading,as the sustained loading increasing,the ultimate carrying capacity were decreased dramatically.
出处
《建筑结构学报》
EI
CAS
CSCD
北大核心
2009年第S2期287-291,297,共6页
Journal of Building Structures
基金
国家自然科学基金项目(50778010)
国家科技支撑计划项目(2007BAF23B02-06)
北京市自然科学基金项目(8092020)
关键词
钢筋混凝土梁
混合侵蚀液体
冻融循环
持续荷载
劣化机理
耐久性
renforced concrete beam
mix-aggressive solution
freeze-thaw circle
persistent loading
deterioration mechanism
durability
