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 × 100 mm, 75 × 150 mm, 100 × 200 mm, and 150 × 300 mm) and 120 concrete cores with two different sizes (50 × 100 mm and 75 × 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.