Influence of river sand moisture content on fresh and hardened concrete properties

Abstract

The fresh and hardened concrete properties are affected by water-cement ratio and the extensive way of water addition in the concrete is from aggregates. Aggregates contain some moisture based on the porosity of the particles and the moisture condition of the storage area. Fine aggregate can contain up to 10% of surface moisture content which causes significant variation in the mixing water content. Therefore the main objective of the study was to study the influence of river sand moisture content on fresh and hardened concrete properties. In the research work, river sand quarried from Gambella and brought Jimma for selling was preferred as it is the commonly used sand in Jimma. Before using the sand in concrete, the physical property tests were conducted to identify as the sand meets the requirements of the standards. The concrete was then mixed varying the moisture contents of the sand from 1% to 10% in steps of 1%. The properties of concrete including workability, unit weight, compressive strength, and split tensile strength were conducted and compared with control and the standard specifications. The results of the Gambella river sand sample material properties test showed a meeting of Ethiopian and ASTM standard specifications. The workability of the concrete showed reduction as the moisture contents of the sand increased. However, the slumps of sand up to 3% moisture contents resulted within 25-50mm. The unit weight of the concrete showed a slight reduction as the sand moisture content increased. But, all the densities of the concrete mix exceeded the 1850kg/m3 which is the maximum density required for lightweight aggregate concrete. Compressive and tensile strengths decreased as the moisture contents of river sand moisture content increased. However, the influence of the moisture contents of river sand was not significant on tensile strength compared to the compressive strength. Meanwhile, the river sand having moisture content up of 9%, 6% and 4% satisfied ACI 209 criteria at 7th, 14th and 28th curing days respectively. Therefore, the moisture contents of the river sand should be considered during mixing the concrete on site and kept constant