【目的】为了研究玻化微珠再生混凝土梁的裂缝发展及最大裂缝宽度,并建立在使用荷载下的最大裂缝宽度计算公式,设计了分别采用玻化微珠加50%掺量再生骨料、玻化微珠加天然骨料和只有天然骨料的混凝土梁的正截面弯曲试验。【方法】设置不同混凝土材料和不同配筋率的两个对照组,比较各试验梁使用荷载下的正截面裂缝发展及最大裂缝宽度。【结果】试验表明:相同配筋率下,玻化微珠混凝土梁的最大裂缝宽度比普通混凝土梁减少19.7%,玻化微珠再生混凝土梁的最大裂缝宽度比普通混凝土梁减少25.4%;相同混凝土配合比下,玻化微珠再生混凝土梁的最大裂缝宽度随配筋率的增大而减小。由于再生粗骨料的天然缺陷及玻化微珠表面封闭内部多孔的材料特点,使得玻化微珠再生混凝土梁的断裂行为不同于普通混凝土梁,结合试验实测结果、理论分析与数学分析,修正了现有规范中的最大裂缝宽度计算公式。

【Purposes】In order to study the crack development and maximum crack width of  glazed hollow beads recycled concrete (GHBRC) beams and to establish the formulae for calculating  the maximum crack width under applied loads, normal section bending tests are designed for concrete  beams containing glazed hollow beads with 50% recycled aggregate, glazed hollow beads with natural  aggregate, and natural aggregate only. 【Methods】 Two control groups with different concrete materi⁃ als and different reinforcement rates were set up to compare the development of cracks and maximum  crack widths in the normal section of each test beam under applied loads. 【Findings】 The test results  show that the maximum crack width of glazed hollow beads concrete (GHBC) beams is 19.7% less  than that of ordinary concrete beams for the same reinforcement ratio, and the maximum crack width  of GHBRC beams is 25.4% less than that of ordinary concrete beams; the maximum crack width of  GHBRC beams decreases with increasing reinforcement ratio for the same concrete ratio. Because of  the natural defects of recycled coarse aggregate and the material characteristics of glazed hollow beads  with closed surface and porous interior, the fracture behavior of GHBRC beams is different from that  of ordinary concrete beams. By combining the experimental results, theoretical analysis, and math⁃ ematical analysis, the formulae for calculating the maximum crack width in the existing codes are re⁃ vised.