Experimental Study on the Crack Width of Glazed Hollow Beads Recycled Concrete Beams under Short-Term Loading

[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 materials 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 mathematical analysis, the formulae for calculating the maximum crack width in the existing codes are revised.