This paper illustrates the hypothetical study conducted when using quarry dust (QD) and sludge in producing 225mm x 225mm x 450mm hollow sandcrete blocks. QD and wastewater treatment sludge (WWTS) were used to replace river sand at 10%, 20% and 30%. Proportions of 50%QD:50%WWTS and 75%QD:25%WWTS were considered for a standard cement to sand combination of 1:6. Water-cement ratio (w/c) was increased as the percentage replacement increased. Specimens were produced and cured via sprinkling for 28 days. They were subjected to compression and water absorption tests. Mix A2 having 75%QD:25%WWTS at 0.55 w/c and 10% sand replacement had the highest compressive strength and water absorption values of 3.69N/mm2 and 6.22% accordingly. These results exceeded the NIS 87:2000 recommendation of 3.45N/mm2 for 225mm load bearing blocks and 12.61% by ASTM C140 respectively. Therefore, QD and WWTS in right proportions can substitute river sand in producing load bearing sandcrete hollow blocks.