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

The concrete containing Type I cement in a structure is cured for 4 days at 75°F, followed by 2 days at 60°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.

A longer yield plateau signifies a _______ brittle material.

A wall footing has the following conditions. Determine the pressure that acts on the bottom of the footing. Assume the footing is 5 ft wide.The bottom of the footing is at a depth of 4 ft below grade.The service dead load is 14.1 kips/ft, and the service live load is 7 kips/ft.The wall is 14 in. thick.The footing is 13 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 = 3,100 psi and fy = 60,000 psi.

A wall footing has the following conditions. Determine the critical bending moment, Mu, at the face of the wall. Assume the footing is 4 ft wide and the pressure that acts on the bottom of the footing is 7,000 psf.The bottom of the footing is at a depth of 2 ft below grade.The service dead load is 14 kips/ft, and the service live load is 7 kips/ft.The wall is 16 in. thick.The footing is 13 in. thick.The allowable soil pressure, qa, is 5,800 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 = 3,400 psi and fy = 60,000 psi.

Prolonged moist curing leads to the lowest concrete strength.

The concrete containing Type I cement in a structure is cured for 2 days at 54°F, followed by 5 days at 63°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 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.

A concrete cube is subjected to biaxial loading. Estimate the compressive strength σ2 if σ1 = 0.3 times the tensile strength, in tension.

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