Palm oil fuel ash (POFA) has become increasingly recognized as an important cement alternative especially in countries that produce large amount of Palm oil such as Thailand and Malaysia. A D-optimal mixture design methodology, was applied for the optimization of concrete with partial replacement of POFA to determine the optimized proportion of POFA, cement and superplasticizer to gain desired compressive and tensile strengths of concrete. It was revealed that POFA and cement increased the compressive and tensile strengths of concrete, however from the regression model obtained, interactions between cement and POFA also decreased the compressive strength. For the tensile regression model, the interaction between cement and super plasticizer leads to a reduction in the predicted tensile strength of concrete. The mixture design is highly beneficial when proposing a new formulation or a new mixture product as it allows the determination of the ideal composition of each component in a mixture, with the purpose of achieving a product with the required features. It is hoped that this book will be beneficial for Science Students as well as Civil Engineers and Architects.