SOME FACTORS AFFECTING THE DYNAMIC MODULUS OF ELASTICITY OF HIGH-STRENGTH CONCRETE

A set of is concrete and six mortar mixes is described, with cube strengths at 28 days of 74 to 117 MPa and electrodynamic E values of 47 to 55 GPa (37 to 42 GPa for the mortar). Very limited potential for increased E is seen after 28 days and comparative detrimental effects are noted due to air-drying and/or self desiccation. Increase from 10 to 15 percent silica fume increases cube strength (by about 3 MPa here) but not E. Ultrasonic pulse velocity and cube strength have expected good correlations with E, the former being closely dependent on mix composition and density. Simple empirical prediction models for E are found to be satisfactory for values up to about 50 GPa for the concretes studied.