Concrete PSI

also called concrete strength, compressive strength, f'c

Concrete PSI is the compressive strength of cured concrete in pounds per square inch. Standard residential and commercial pours range from 2,500 to 5,000 PSI; structural and industrial pours can exceed 8,000 PSI.

Strength is specified by the structural engineer and verified by cylinder testing at 28 days. Common applications: 2,500 PSI for non-structural slab on grade, 3,000 PSI for residential footings and slabs, 4,000 PSI for commercial slabs and structural concrete, 5,000+ PSI for column and high-load structural concrete.

Higher PSI requires higher cement content (and often admixtures), which raises the per-CY price. A 5,000-PSI mix can cost 10-20% more per CY than 3,000 PSI. Use the structural engineer's specified strength — over-specifying wastes money.

Mix design notation: '4000 psi, 3/4 SAG, 4-6 inch slump' means 4,000 PSI strength, 3/4-inch maximum aggregate size, 4-6 inch slump on delivery. The supplier's mix-design sheet lists cement content, aggregate gradation, and admixtures.

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