Effect of size and type of fine aggregates on flowability of mortar

The present study investigated how the aggregate characteristics namely individual size, grade and type affects flowability of mortar mixes. Two types, river sand and crusher dust four single sizes namely 1.18 mm, 0.600 mm, 0.300 mm, 0.150 mm and for single gradation of each fine aggregate were considered in the present research work. In total, 103 mortar batches was made with three different sand to cement ratios [s/c] and two different water to cement ratios [w/c] to find out the flowability of mortar and tested using standard flow table. Out of 103 mortar batches, 52 were with river sand and 51 were with crusher dust. Tests were performed as per ASTM 109 standards. S/c ratio varied from 1 to 3 with an increment of one and w/c ratio was chosen in such a way that all the mixes to give measurable flow. The influence of particle shape and surface texture of aggregate were characterized with an angularity test based on ASTM C1252 in terms of percent of air voids in a loosely compacted fine aggregate. The results indicate that the size of aggregate and uncompacted void content have greater impact flowability of mortar. Mortar made with river sand has got better flowability than that of mortar made with crusher dust due to its higher degree of irregularities. Mortar with higher aggregate content has low percentage of spread compared to mortar with low aggregate content. Similarly, graded aggregate has lesser percentage of spread due to its proper packing compared to single sized aggregates.