Effects of Coating Aggregates on Dynamic Properties of Concrete by Impact Resonance Method

Concrete structures may be subjected to dynamic loadings like earthquakes, impact, and vehicular loads. These loads may cause considerable damage to infrastructures and shorten their life span. To reduce the effects, improving concrete’s dynamic properties is important. This can be done using granular elastic components and fibers in the production of concrete. This research explores the influence of using coated aggregates on the physical, mechanical, and dynamic properties of concrete. Experimental investigation on concrete with epoxy, epoxy-sand, and epoxy-crumb rubber as a partial replacement of coarse aggregates at different volume fractions ranging from 5% to 20% was conducted. Furthermore, the dynamic modulus of elasticity of concrete with coated aggregate was determined by measuring the resonant frequencies of flexural vibrations in a prismatic beam using an impactor (hammer). Results indicate that partial replacement of epoxy-crumb rubber coated aggregates in concrete shows a reduction in mechanical proprieties. However, significant improvements in the mechanical and dynamic properties of concrete were observed by the partial replacement of coarse aggregates with epoxy and epoxy-sand coated aggregates. Compressive strength and dynamic elastic modulus were enhanced by 12% and 10%, respectively, when concrete with 15% epoxy-sand coated was used. The results showed that concrete specimens using epoxy and epoxy-sand coated as a partial replacement for coarse aggregate have higher mechanical properties as compared to those of concrete specimens with epoxy-crumb rubber-coated aggregates. Moreover, the results showed that the calculated values of the dynamic modulus of concrete using the empirical relations proposed by Popovics and Hansen were overestimated as compared to the experimental values.