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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。
The rapid freezing and thawing experiments were carried out in a laboratory to study the mechanism of the mechanical properties deterioration of the continuous reinforced concrete beams under the action of alternating freeze-thaw and erosion solutions. The etching solution was mixed with 3% sodium chloride and 0.34% magnesium sulfate to make. The effect of different continuous loads on the bearing capacity of RC beams after 300 cycles of freeze-thaw cycles and immersion in erosive solution was investigated. The SEM and X-ray diffraction (XRD) Hydration products and microstructure of beam body concrete. The results of tests and tests show that with the increase of the continuous load level, the microcracks in the concrete expand more obviously and the salt crystals become more obvious under the alternation of the freeze-thaw cycles and the soaking of the erosion solution. The salt products in the concrete also increase obviously. Corrosion degree increases, leading to the ultimate bearing capacity of the beam significantly reduced. It can be seen that the continuous load accelerates the deterioration of concrete and steel under the effect of freeze-thaw cycles and erosion solution. That is, the higher the continuous load, the greater the decrease of the ultimate bearing capacity of the reinforced concrete beam.