Concrete Pixels

As I am involved in the splitting tensile strength of concrete in our project, the construction of OL3 Nuclear Power Plant, I have made some research on this subject. There have been so many studies/models made to date inorder to estimate the splitting tensile strength of normal weight concrete from higly respected institutes like ACI,CEB-FIP and from other individual so called concrete experts. But there is one study made by Nihal et al as published in the ACI Materials Journals in early February 2006 that summarizes and evaluates around 12 splitting tensile equations and proposed a very convincing equation. The splitting tensile strength of concrete is normally expressed as A*fc^B where A & B are some constants and fc is the cylinder compressive strength of concrete. Of the 12 models, it’s very interesting to note the constants; A varies from 0.294 to 0.59 and the power B from 0.50 to 0.71. The evaluation of the different equations was made using the integral absolute error (IAE). The lower the IAE the better is the result. What surprised me most is the equation in ACI 363R & 318 are giving poor estimates. To some extent it is fairly acceptable for concretes between 20-40 MPa compressive strength. For strengths > 40MPa it is underestimating the splitting tensile strength. The equation by CIB-FIB where A=0.3 and B=0.6667 is far better in most range of compressive strengths from 0-120 MPa. A slightly more accurate though is the one proposed by Nihal, et al in which A=0.387 and B=0.63. So for those that requires a higher degree of accuracy for the splitting tensile strength, try the equations of Nihal, et al or the CEB-FIP or better still do some extensive experiments to validate this finding if not convinced. Given the splitting tensile strength of concrete, the direct tensile strength can be easily estimated.