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Compressive Strength

Compressive strength is how much a material can be squeezed or pushed together before it breaks.

Think of it this way

A stack of crackers on a plate shows compressive strength. Press down lightly and the stack holds. Press too hard and the crackers crush and crumble. The crackers' compressive strength is how much force they can take before they break.

Explaining compressive strength by grade level

Think about pressing down on a brick made from sand. If the brick is strong, it holds its shape. If it is weak, it crumbles apart. Bigger grains of sand can lock together and make a brick that is harder to crush.

Projects that explore compressive strength

Sand Particle Size and Brick Strength

Sand particle size turns out to matter more than you might expect. When you mix Portland cement with large #8 silica sand, the finished bricks averaged 6,610 kg under compression before cracking. Switch to fine #30 sand — same cement, same water — and that number drops to just 4,281 kg. The coarser particles change how well cement resists being squeezed together, and the compression tester makes that difference concrete.

Hard