Abstract:
This study investigates the fresh and hardened state properties of cement-sand mortar comprising manufactured sand and offshore sand as alternatives for a complete replacement of river sand. Two types of
manufactured sand were selected based on different rock types such as Hornblende-Gneiss and
Charnockite. Offshore sand was collected from an open stock pile after required period of washing.
Mortars were manufactured with a binder of Portland Limestone Cement. Binder-to-aggregate ratios of
1:3, 1:4 and 1:6 were considered in this study and manufactured sand was replaced at 0%, 25%, 50%
and 75% with offshore sand. To check the influence of sand alternatives and blending ratios, fresh and
hardened state properties of alternative mortars were analyzed and compared with reference mortars
which were made with river sand alone. Wet and dry bulk densities of mortars were increased with lower
replacement levels with offshore sand. Most mortars with blended sand improved the workability while
consistency and initial setting time of mortars were not significantly affected. Inflated bleeding of mortars was noticed with the alternatives and replacement levels. Workable life was decreased at small
replacements. When manufactured sand in mortar content was 25% and 50%, the water retentivity
was significantly improved than other replacements and control mixes. Mortars at lower replacements
greatly advanced the flexural strength, compressive strength and capillary water absorption. Linear
shrinkage and thermal expansion of mortars were also affected with the selected replacement levels.
Based on the overall performance of mortars, blended sand at 25% replacement of manufactured sand
with offshore sand was deduced as the feasible solution for completely replacing river sand and to produce economical mortars.
