Behavior of High Strength Concrete Containing Nano- Metakaolin Exposure to Fire Flame

Abstract

The aim of this experimental study was to evaluate the effect of fire flame exposure with different intensities of firing on the mechanical properties of a high strength concrete (HSC). Many variables were encountered in this study. Two mixes of 80 MPa target compressive strength (1:1.22:2) with 3% Nano-Metakaolin and the other with 5% were used. Two types of coarse aggregate were used (natural crushed gravel and crushed dolomite rock with maximum size of 14mm). The specimens were moist cured for 28 days, air-dried in the laboratory to firing at ages 90 days at three temperature levels (400, 600, 800)oC and for three exposure periods (1, 1.5 and 2 hours). Different methods were used to cool specimens. The reduction values of compressive strength for all mixes ranged between (2-69.5)% at 400oC, (8-72)% at 600oC and (10-85)% at 800oC , the reduction values of splitting tensile strength were (9-43.2)%, (17-50)% and (39-76)%, and the reduction values of flexural strength were (51.7-84.8)%, (52.8-87) %, (53.6-87.8)%, respectively.