Effects of Aggregate on Flow Properties of Mortar

The effects of aggregate characteristics on flow ability of mortar mixtures were investigated. Two types, five single sizes, and three gradations of fine aggregate were considered. Uncompacted voids of the aggregates were measured. Flow properties of 166 mortar batches made with the aggregates, together with different sand-to-cement ratios (s/c) and water-to-cement ratios (w/c), were evaluated using the ASTM C109 flow table test method. The results indicated that w/c, uncompacted voids, size, and volume of aggregate have a great impact on mortar flow ability. Generally, aggregate having higher uncompacted void content provides mortar with a lower flow. When aggregate content was low (s/c=1), the size of aggregate had little effect on flow ability of the mortar; while aggregate content was high (s/c=3), the size of the aggregate significantly influenced the mortar flow ability. A statistical model was developed for predicting flow ability of mortar.