Abstract:
Usage of alternative fine aggregates in concrete and cement mortar has been gradually increasing
by the construction industries around the world due to the escalated shortage in obtaining natural
river sand. Manufactured sand and offshore sand can be considered as the principal alternatives
which are consumed by most of the contractors for substituting river sand in the construction
activities now. However, most of the above sand consumptions are done without deeply analyzing
the conformity of the alternatives to concrete and cement mortar. The present study is executed to
inspect the fitness of manufactured sand from two different high-grade metamorphic rocks,
offshore sand, and blended sands of both manufactured sand types at 25%, 50% and 75%
replacement levels with offshore sand to be practiced in concrete and cement mortar by
scrutinizing physical properties and quality through series of characterizing experiments. Results reveal that blended sand with all replacement levels can be suitable with respect to particle
characteristics such as angularity, surface texture and total specific surface. Regarding resultant
particle size distribution, blended sands with 50% replacement level can be the optimum solution in
reference to uniform gradation, the density of sand mix, and fineness. 50% and 75% contents of
manufactured sand in combined sand types show higher loose and packing densities than river
sand. Flowability under the gravity of blended sand types contain 50% to 75% of offshore sand are
performed well contemplating different affecting parameters. However, increased manufactured
sand content demands more water than river sand and offshore sand. Additionally, hazardous
materials such as clay lumps and friable particles, fines and silt are identified within the permissible
range based on the requirements by the standard available. Regarding all the above
characteristics, blended sands contain two manufactured sand types with 50% replacement level
with offshore sand can be suggested as the optimum substitution for river sand in terms of fresh
and hardened state properties of concrete and cement mortar.
