Effects of Size and Uncompacted Voids of Aggregate on Mortar Flow Ability

Abstract

The effects of aggregate characteristics on the flow ability of mortar mixtures were investigated. Two types, five single-sized and three graded fine aggregate were considered. Uncompacted voids of the aggregates were measured. Flow properties of 166 mortar batches made with different aggregates, sand-to-cement ratios (s/c) and water-to-cement ratios (w/c), were evaluated using the modified ASTM C109 flow table test method. The results indicated that in addition to w/c, the content, uncompacted voids, and size of aggregate all significantly affect mortar flow ability. Generally, aggregate having higher uncompacted void content provides its mortar with a lower flow. When aggregate content was low (s/c = 1), aggregate size had little effect on the flow ability of the mortar; when aggregate content was high (s/c = 3), aggregate size significantly influenced the mortar flow ability. The mortar with graded aggregate has better flow ability than the mortar with single-sized particles. River sand provides a mortar with better flow ability when compared to limestone. A statistical model was developed to predict the flow ability of mortar. The model can also be used to study the effect of different parameters on mortar flow properties.