Dynamic Tests of Model Concrete

Résumé du livre

The objective of the project was to evaluate the dynamic properties of modeling materials. Dynamic tests were conducted on microconcrete with no. 4 and no. 30 maximum aggregate size, and gypsum concrete with no. 4 maximum aggregate size. The effects of strain rate (up to 2.5 in./in./sec) on ultimate compressive strength were obtained. The results are compared with results of dynamic tests conducted on prototype concrete by others. Microconcrete with a no. 4 macimum aggregate gives good correlation with prototype values of dynamic strength increase. The ratio of dynamic to static modulus of elasticity with increasing strain rate and dynamic strength increase factor also gives good correlation. Microconcrete with a maximum aggregate size of no. 30 gives dynamic increase factors somewhat lower than those of the prototype. The ratio of dynamic to static modulus of elasticity with increasing strain rate is greater than that of the prototype or microconcrete with no. 4 macimum aggregate. Both microconcretes experience higher strains at ultimate load than the prototype. Gypsum concrete experiences dynamic strength increase factors of approximately half those of the prototype. It may be significant that the increase in modulus of elasticity with increasing strain rate for gypsum concrete is not similar to that of prototype concrete. Strains in gypsum concrete at ultimate load are slightly higher than those for prototype concrete. (Author).