A study on the correlation of the compressive strength between 75x150mm, 100x200mm, 125x250mm and 150x300mm concrete cylinder specimens

In the Philippine construction industry, the benchmark for the basis of the strength of the concrete is by testing concrete cylindrical specimen of diameter of 150mm by height of 300mm. The testing is done by applying destructive method through a uniaxial compressive machine. However, due to the rise of high strength concrete, the demand on the usage of higher capacity of testing machine increases. A correlation between smaller specimens strength to the standard specimen\u27s strength is proposed to serve as a possible solution to the need of higher capacity testing machine. Not only could it reduce the cost of acquiring a higher capacity testing machine but also can provide advantages in many ways such as handling, storage, and lesser waste in term of volume. This study tests a number of concrete cylindrical specimen specifically 8 different batches of concrete mixtures with 4 different specimen sizes under each batch. Linear and non-linear regression analyses were used to establish the correlation of the strength of concrete between different specimen sizes. Exponential regression was chosen to represent the correlation between the compressive strength of the concrete between the 150 x 300 mm specimen size and other smaller specimen sizes. The result is based on the r-value from various regression analyses. in the analysis, it shows that the difference of materials used in different concrete batches also contribute a different correlation. With the correlation made, testing of smaller concrete cylindrical specimen can now estimate the equivalent compressive strength if the 150 x 300mm is tested. This result could now decreases the demand of the high capacity testing machine and also gives an overview on how the size of specimen and materials could affect the compressive strength of the concrete