Effect of coarse aggregate on the workability of sandcrete

The results of an experimental study of the effect of a limited quantity of coarse aggregate on the workability of sandcrete are presented. This study has been conceived within an experimental design framework. Several parameters have been analyzed: aggregate content, aggregate size, aggregate shape and matrix strength (20- and 35-MPa matrices are cast). Statistical analysis shows that, for the 20-MPa matrix, aggregate content [gravel/sand ratio (G/S)<0.7] and aggregate size appear to be the most influent parameters. While for the 35-MPa matrix, only the aggregate concentration has a statistically significant effect. These results show that the workability can be divided by 4 as the aggregate content increases up to G/S=0.6. Thus, sandcrete with a small coarse aggregate content cannot be considered as a classical sandcrete whose mechanical properties, mainly compressive strength, are enhanced by an amount of gravel. Developing general use of sandcrete with coarse aggregate requires building specific mix design to respect both compressive strength and workability.