Evaluating The Empirical Formula Used In Ebcs-2 1995 To Calculate The Tensile Strength Of Concrete

Abstract

Tensile strength is important for plain concrete structures such as dam under earthquake excitations. Other structures for example pavement slabs and airfield runways, which are designed based on bending strength, are subjected to tensile stresses. Therefore, in the design of these structures, tensile strength is more important than compressive strength. The relationship of tensile strength with the compressive strength for different range of concrete strength proposed by various authors and country standards indicate diverse and wide variations in recommendations to predict the concrete tensile strength. Predicting the tensile strength of concrete from its compressive strength has been under scrutiny for a long time. Many researchers have investigated its prediction accuracy, i.e., how well it correlates with or predicts test data. The aim of this study is to evaluate the empirical formula used in EBCS-2 1995 to calculate the tensile strength of concrete. To achieve this concrete mix design was provided to attain the target compressive strengths of 25, 30 and 35 Mpa by following the specification provided in the ACI manual. For each target strength three compressive strength test, three center point loading test and three splitting tensile test for 7 and 28 days were conducted. Therefore, the total number of sample size for the experiment was 36 cylindrical samples and 18 beam samples. After the experimental study the following conclusion has been made. The ACI code provides adequate relation in the prediction of splitting tensile strength .while EBCS-2 1995 underestimate the tensile strength. In the case predicting the flexural strength of plain concrete EBCS-2 1995 gives the closer value to actual flexural strength at latter age. But at early age ACI gives the closest value to actual strength. The empirical formula used in EBCS-2 1995 to calculate the tensile strength of a concrete need further study.