Concrete Production Plant Variables Affecting Flexural Strength Relative to Compressive Strength

Some project specifications allow the substitution of compressive strength for flexural strength testing for the quality control of projects in which flexural strength is the critical type of strength, such as for pavements. There are certain errors during the production of concrete and aggregate in which the use of compressive strength quality control testing may not be sufficiently sensitive to detect significant changes in flexural strength. A survey of concrete production operations revealed that numerous production errors (variables) commonly occur in practice. Thirteen of these plant production variables were examined for their effects on changes in compressive strength relative to flexural strength. Combining the results of the present study with data reported from the literature indicated that compressive strength may be less sensitive than flexural strength to changes in aggregate particle shape and texture, gradation, maximum aggregate size, aggregate source mineralogy, mineral filler/dust content, deleterious material, and possibly aggregate coatings and water-cementitious material ratio. Thus, under certain conditions, it may be unconservative to use compressive strength testing in lieu of flexural strength testing for quality control. (C) 2014 American Society of Civil Engineers.