| Title |
Effect of Elevated Temperature on Changes of Color and Residual Compressive Strength of Concrete |
| Keywords |
High Temperature ; Concrete ; Color Changes ; Residual Compressive Strength |
| Abstract |
When reinforced concrete is subjected to high temperatures, compressive strength and elastic modulus of concrete, ductility and yield stress of steel decrease. Degradation of these properties after such an exposure may result in undesirable structural failures and are great importance in terms of the serviceability of buildings. Therefore, changes in material's properties have to be evaluated in decide whether the buildings exposed to high temperature effect will be repaired or demolished. Assessment of fire damaged concrete usually starts with visual observation of color change, crazing, cracking, and spalling. On heating, a change in color from normal to a pink/red is often observed and this is useful since it coincides with the onset of significant loss of concrete strength. The purpose of this study is to quantify changes in color for concrete using spectrophotometric method and to identify the relationship between color change and residual compressive strength loss of concrete as temperature increases. For this purpose, we manufactured concrete samples with varying water-to-cement ratios and heated them to target temperatures of 100, 200, 300, 400, 500, 600, 700 and 800℃ in an electric oven, whereupon their color changes and residual compressive strengths were measured for analysis. The result of the study shows that color change and residual compressive strength in a concrete structure exposed to high temperature have a consistent relationship in quantitative equation, therefore, it may be possible to know how much compressive strength of the concrete reduces by measuring color changes and estimating heating temperature. |