Does coarse sand or fine sand make a stronger brick? The size of the sand particles mixed into cement changes how the finished brick holds together. You mix two batches of bricks. One uses large #8 silica sand. The other uses fine #30 silica sand. Both get the same amount of Portland cement and water. After three days of curing you run three tests: - a drop test from eight feet - a hanging weight test - a compression test with a soil lab machine The larger #8 sand produced stronger bricks in nearly every test. Under compression the #8 bricks averaged 6,610 kg before cracking. The #30 bricks averaged only 4,281 kg.