Associate professor, School of Architecture and Environmental Design, California Polytechnic State University, San Luis Obispo, Calif.
In the mix proportioning process, the concept of minimum voids and the principle of minimum surface area are basically in conflict with each other. The former implies that a blend of several fractions of coarse aggregate is always superior to a single fraction. The latter states that for a given maximum size of aggregate a single fraction is superior to any blend. Between the two extremes—continuous gradation, on the one hand, and a single fraction of coarse aggregate, on the other—lies the vast and largely unexplored gray area of gap-graded mixes. In spite of the great variety of gradation patterns available in this area, certain general principles can be delineated and translated into a system of mix proportioning that is applicable to the total spectrum of concrete mixes.
Paper ID: CCA10177J