Mechanical Properties of High-Strength Concrete at Elevated Temperatures.

摘要

This report describes results of NIST's experimental program on the effects of elevated temperature exposure on the mechanical properties of high strength concrete (HSC). Mechanical properties were measured by heating, with and without preload, the 100 mm x 200 mm HSC cylinders to different target temperatures, and loading them to failure while hot or after the specimens had cooled to room temperature. The specimens were heated at slow heating rate of 5 degrees C/min to prevent large thermal gradients. The maximum target temperature was 600 degrees C. The test specimens were made of four HSC mixtures with water-cementitious material ratios (w/cm) ranging from 0.22 to 0.57, and room temperature compressive strength at time of testing ranging from 51 MPa to 93 Mpa. Two of the four HSC mixtures contained silica fume. Experimental results indicate that HSC with lower w/cm and with silica fume have higher relative relative residual strength after elevated temperature exposure than those with higher w/cm and without silica fume.