Background: The cracking load is an important parameter in the design and testing of beam
structures according to the recent patents. Compared to ordinary concrete, recycled aggregate concrete
components are more prone to cracking.
Methods: In this paper, the calculation method and the size effect of the cracking load for the recycled
aggregate concrete beam were studied. Four recycled aggregate concrete beams with different sizes
were tested by the four-point bending experiment to obtain their cracking loads. According to the comparison
of the tested values and the calculated values by two existing methods, it was found that the existing
calculation methods are only suitable for small-sized beam specimens. The main reason for the
calculation error lies in the fact that the existing calculation method does not consider the size effect of
tensile strength of recycled aggregate concrete.
Results: It is very necessary to modify the existing formulas to calculate the cracking load more accurately
for large-size beam specimens. Therefore, this paper presents an improved formula for the cracking
load calculation by considering the size effect. The calculated results obtained by the proposed
method are closer to the test values than those obtained by the original methods.
Conclusion: It has been shown that it is necessary and reasonable to consider the size effect in the calculation
of the cracking load of the recycled aggregate concrete beam.