Mechanical Properties of High-Strength Concrete

Researchers conducted an experimental program to investigate production techniques and mechanical properties of high-strength concrete and to provide recommendations for using these concretes in manufacturing precast/prestressed bridge girders.

High-strength concretes with 28-day compressive strengths in the range of 8,000 to 18,600 psi (55.2 to 128 MPa) were produced. Test variables included total amount and composition of cementitious material, portland cement, fly ash, and silica fume; type and brand of cement; type of silica fume, dry densified and slurry; type and brand of high-range water-reducing admixture; type of aggregate; aggregate gradation; maximum aggregate size; and curing.

Testing determined the effects of these variables on changes in compressive strength and modulus of elasticity over time, on splitting tensile strength, on modulus of rupture, on creep, on shrinkage, and on adsorption potential as an indirect indicator of permeability. The study also investigated the effects of test parameters such as mold size, mold material, and end condition. More than 6,300 specimens were cast from approximately 140 mixes over a period of three years.