Effect of high temperature on concrete behaviour

Effect of High Temperature on Concrete BehaviourNesil MAHSANLARABSTRACTThe physical and mechanical properties of reinforced concrete structures change if theyare exposed to high temperatures. The changes in the properties of the reinforcedconcrete causes cracks and spalls which weakens the bonds between the bar and theconcrete. Therefore, before deciding whether structures exposed to high temperaturesshould be repaired or demolished, their final state should be carefully examined.In this study, the effects of temperature and cooling regimes on the physical andmechanical properties of the concrete were observed. The concrete production was madewith CEM I 42,5 R cement, siliceous aggregates, silica fume, fly ash and slag. Mineraladmixtures replaced 10 % cement by weight. These concretes were exposed to 100, 200,300, 600, 900 and 1200 ºC. Samples cooled to the room temperature in water and in air.Control tests were applied on these samples and Munsell Color System components hue,value and chroma were measured by spectrophotometer.Test results showed similarities in the change of compressive strength and color ofconcrete which exposed to high temperature. A relationship is established betweencompressive strength and the color change of concrete. This relationship is expected toshow us residual strength of the concrete and the temperature that it was exposed to,based on the color measurements taken from the concrete structure.Keywords: Compressive strength, concrete, pozzolan, color, high temperature