Exceptional shrinkage can occur when concrete is _______.

A wall footing has the following conditions. Determine the depth, d, of the reinforcement. Assume the footing is 4 ft wide, the pressure that acts on the bottom of the footing is 5,300 psf, and the reinforcement is a #8 bar spaced every 12 inches.The bottom of the footing is at a depth of 5 ft below grade.The service dead load is 7 kips/ft, and the service live load is 8 kips/ft.The wall is 14 in. thick.The footing is 14 in. thick.The allowable soil pressure, qa, is 5,500 psf.The soil has a density of 125 lb/ft3.The concrete has a density of 150 lb/ft3.The concrete cover has a thickness of 3 in.f’c = 3,600 psi and fy = 60,000 psi.

The concrete containing Type I cement in a structure is cured for 3 days at 40°F, followed by 5 days at 71°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 4 days at 53°F, followed by 4 days at 52°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.

Although concrete is made up of essentially elastic, brittle materials, its stress-strain curve is nonlinear and it appears to be somewhat _______.

Carbonation shrinkage occurs without the loss of moisture due to hydration reactions inside the cement matrix.

Increasing the water/cement ratio of concrete might make it _______ but also _______.

Concrete near the top of deep members tends to be stronger than the concrete lower down.

A wall footing has the following conditions. Determine the pressure that acts on the soil. Assume the footing is 4 ft wide.The bottom of the footing is at a depth of 4 ft below grade.The service dead load is 6 kips/ft, and the service live load is 6 kips/ft.The wall is 14 in. thick.The footing is 13 in. thick.The allowable soil pressure, qa, is 4,000 psf.The soil has a density of 110 lb/ft3.The concrete has a density of 150 lb/ft3.The concrete cover has a thickness of 3 in.f’c = 3,000 psi and fy = 60,000 psi.

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?