超高韧性水泥基复合材料取代保护层混凝土梁抗锈蚀性能研究

Corrosion resistance of reinforced concrete beams with cover replaced by UHTCC

将超高韧性水泥基复合材料(UHTCC)应用于钢筋混凝土梁的保护层,制作受拉侧UHTCC保护层厚度为15mm(不包含受拉钢筋)、50mm(包含受拉钢筋)的钢筋混凝土/UHTCC复合梁及全梁均为UHTCC和混凝土的4种简支梁,在人工加速锈蚀条件下使主筋锈蚀,考察采用UHTCC做钢筋混凝土梁保护层对于抑制钢筋锈蚀引起保护层锈胀开裂的功效,并对锈蚀后梁的弯曲性能进行试验研究和分析。结果表明,UHTCC部分取代保护层混凝土(包含受拉钢筋)能有效抑制或延缓钢筋锈蚀引起的保护层开裂,有效提高混凝土结构或构件的服役寿命。锈蚀后梁的弯曲试验表明,利用UHTCC部分(50mm)或全部取代混凝土梁钢筋锈蚀后梁破坏形式不发生变化,承载力下降不明显。

Four types of beams,including reinforced concrete beam with the cover zone replaced by ultra high toughness cementitious composites（UHTCC）（thickness 15mm if not counting the reinforcements,50mm if counting the reinforcements）,reinforced concrete beam and reinforced UHTCC beam,were manufactured.The corrosion process of the reinforcing bars was artificially accelerated,inducing different degrees of corrosions.The time when the first crack occurred was recorded and the beams with different corrosion ratios of the reinforcing bars were tested under four-point bending for their load-deflection relations.The results showed that UHTCC could effectively restrict or delay the process of cracking of the cover due to corrosion expansion,alter the crack pattern,and delay the appearance of first corrosion expansion crack,thereby increasing the service life of reinforcement concrete structures or components.Meanwhile,the bending tests of the beams after accelerated corrosion showed that for beams with a cover of 50mm UHTCC or completely replaced with reinforced UHTCC,respectively,the strength reduction and change of failure pattern after corrosion were both insignificant.