Concrete subjected to critical stress of about _______ of its short-time strength will eventually fail under that load.

The concrete containing Type I cement in a structure is cured for 4 days at 70°F, followed by 4 days at 65°F. Use the maturity concept to estimate its strength as a percentage of the 28-day strength under standard curing. Maturity is defined as M = Σ(Ti + 50)(ti) where Ti is in degrees F and ti is in days.

The concrete containing Type I cement in a structure is cured for 2 days at 58°F, followed by 2 days at 43°F. Use the maturity concept to estimate its strength as a percentage of the 28-day strength under standard curing. Maturity is defined as M = Σ(Ti + 50)(ti) where Ti is in degrees F and ti is in days.

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

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

Prolonged moist curing leads to the lowest concrete strength.

A wall footing has the following conditions. Determine the pressure that acts on the bottom of the footing. Assume the footing is 4 ft wide.The bottom of the footing is at a depth of 2 ft below grade.The service dead load is 9.7 kips/ft, and the service live load is 6.9 kips/ft.The wall is 12 in. thick.The footing is 12 in. thick.The allowable soil pressure, qa, is 4,900 psf.The soil has a density of 115 lb/ft3.The concrete has a density of 150 lb/ft3.The concrete cover has a thickness of 3 in.f’c = 3,200 psi and fy = 60,000 psi.

The increase in the volume of concrete during hardening and drying under constant temperature is called shrinkage.

Although concrete is made up of essentially elastic, brittle materials, its stress-strain curve is nonlinear.

Which symbol is used to represent concrete’s compressive strength?