Evaluation of In-Place Flexural Strength of Concrete
Muzaffer Yener and Wai F. Chen
Appears on pages(s):
compressive strength; concretes; cylinders; evaluation; flexural strength; nondestructive tests; statistical analysis.
The differential influence of six potentially significant parameters aggregate size, aggregate shape, water-cement ratio, age of concrete, curing conditions, and cement types - were examined experimentally to develop empirical relationships correlating breakoff strength and conventional flexural strength of concrete. Conventional cylinders were also tested to determine possible correlation between the breakoff and compressive strengths of concrete. Evaluation of results of 122 breakoff, 140 beam, and 110 cylinder tests indicates that water-cement ratio, age of concrete, curing conditions, and cement type have a significant differential effect on breakoff and beam tests and that all six of the parameters display a differential effect on breakoff and cylinder tests. Because correlation of breakoff strength and compressive strength proved to be highly impractical, linear regression analyses were executed only to correlate beam and breakoff strengths as a function of water-cement ratio. The statistical relationships developed between beam strength and breakoff strength as measured in the present investigation are valid only for 7-day strength, Type I cement concrete cured under moist conditions. Modification of the breakoff testing procedure may alleviate the dependence of the relationship between the two strengths on these parameters.