Weibull statistical analysis and experimental investigation of size effects on the compressive strength of concrete-building materials

From an extensive experimental program performed on 240 molded concrete specimens with four different cylindrical sizes (50 x 100 mm, 75 x 150 mm, 100 x 200 mm, and 150 x 300 mm) and 120 concrete cores with two different sizes (50 x 100 mm and 75 x 150 mm), prepared from two different mixtures, this study demonstrates that (i) concrete clearly exhibits the size-dependent behavior for the mean value, the associated variability, and the probability distribution of the compressive strength, regardless of specimen size and mix proportion; (ii) there is no significant impact of sample size on the relationship between the compressive strength of the cylindrical molded and that of the cored concrete specimens; (iii) the influences of both the sample and aggregate sizes on the compressive strength of concrete would be less important with increasing specimen size, meaning that a very large concrete sample would have a constant strength; and (iv) the Weibull statistics is irrelevant in interpreting the statistical size effect on the compressive strength of concrete.

Automated summary

This study, based on extensive experimental research on concrete specimens and cores, reveals that concrete exhibits a size-dependent behavior in terms of compressive strength regardless of specimen size and mix proportion. However, the relationship between compressive strength of cylindrical molded and cored concrete specimens is not significantly impacted by sample size. Additionally, the influences of sample and aggregate sizes on compressive strength decrease with increasing specimen size, suggesting that very large concrete samples have a constant strength. The use of Weibull statistics is irrelevant in interpreting the statistical size effect on compressive strength of concrete.