Professor, University of Calgary, Calgary, Alberta
The first-crack strength and toughness parameters of steel fiber-reinforced beams were determined according to ASTM Test Method for Flexural Toughness and First-Crack Strength of Fiber-Reinforced Concrete (Using Beam with Third-Point Loading) (C 1018–92). The objective was to establish the effects of the testing rate, defined in terms of machine stroke, and concrete age at test on Method C 1018 test results. Machine stroke rate varies from the standard specified in Method C 1018 to 20 times the standard rate. Concrete age at test varies from 3 to 92 days. Sets of four beams were tested at each of five stroke rates and five test ages. Linear regression analyses show statistically significant increases in first-crack strength with increase in machine stroke rate or test age. Similar analyses show that in most cases toughness indices and residual strength factors are not affected by machine stroke rate or test age to a statistically significant degree.
Paper ID: CCA10587J