The strength of concrete under biaxial compression is less than the uniaxial compressive strength.

A group of 20 tests on a given type of concrete had a mean strength of 4,800 psi and a standard deviation of 400 psi. Does this concrete satisfy the strength requirement for 4,500 psi concrete?

The standard compressive strength acceptance test is performed on concrete cylinders that are how old?

Prolonged moist curing leads to higher concrete strength.

This shrinkage occurs without the loss of moisture due to hydration reactions.

What does the “c” represent in f’c?

Drying shrinkage occurs in carbon-dioxide rich atmospheres.

The three most common durability problems in concrete structures are corrosion of steel in the concrete, breakdown of the structure of the concrete due to freezing and thawing, and breakdown of the structure of the concrete due to a chemical attack.

There is a permanent reduction in strength when concrete is exposed to sustained high loads.

A concrete cube is subjected to biaxial loading. Estimate the compressive strength σ1 if σ2 = 0.8 times the compressive strength, in compression.