Testing the Compressive Strength of Concrete: Comparing Direct Test Results with Conversion Values Firmanilah Kamil, Julyan Purnomo
Politeknik Negeri Ketapang
Abstract
This study discusses testing the compressive strength of concrete at 7 days, 14 days, and 28 days, and evaluates the accuracy of the conversion values used to estimate the compressive strength of concrete at older ages. The compressive strength of concrete is an important parameter in assessing the quality and resistance of materials to structural loads. Direct testing at various ages gives an idea of the development of concrete strength, but in many cases, conversion values are used to save time and cost. This study conducted experimental tests in the laboratory, where concrete samples were tested at 7, 14, and 28 days of age. These test results were then compared with conversion values calculated using empirical formulas commonly used in the concrete industry. The results showed that there were significant differences between the direct test results and the conversion values, especially for concrete with additives such as fly ash and rice husk. The conversion values from 7 days to 28 days are often inaccurate, while the conversion from 14 days to 28 days is closer to the direct test results. Factors such as the type and proportion of additives, curing conditions, and the mismatch of the conversion model with the strength development of the concrete also influenced the final results. These findings emphasize the need for caution in using conversion values to assess the compressive strength of concrete to ensure the quality and safety of structures.
Keywords: Age of concrete, Concrete compressive strength, Concrete testing, Conversion value, Curing concrete
