Concrete behavior under high temperatures in factorial experimental design with star configuration

Abstract Motivated by the need for studies on the residual capacity of concrete after high temperature situations, this research study presents the use of the experimental design planning methodology with star configuration, formally denominated central composite rotatable design (CCRD), to study the compressive strength of concrete specimens heated in ovens. With the use of this tool, the variables water/cement ratio and temperature were analyzed together, taken each at five different levels, according to a predefined statistical methodology. We also used thermogravimetric tests that allow verifying the different levels of damage for different points of the cross section and the effect of carbonation and rehydration on the concrete. In addition, the study detected the existence of an intermediate zone at which the temperature increases the production of hydration products, leading to a discussion about the protection of concrete structures by controlling the water/cement ratio.