Impact Tests on Cement-Based Fiber Reinforced Composites

This paper describes the construction of two simple impact machines--one small with a capacity of 100 Joules and the other large with a capacity of 1,000 Joules--designed to conduct impact tests on fiber reinforced mortars and concretes in the uni-axial tensile model. During a test, the applied load, accelerations, and velocities are measured such that with a proper analysis scheme, the raw data can be analyzed to obtain fundamental material properties under impact loading. Carbon, steel, and polypropylene micro-fiber reinforced mortars and steel fiber reinforced concrete were tested and it was demonstrated that the proposed technique is a simple and rational method of obtaining meaningful material properties. In general, fiber reinforced composites were found to be more impact resistant than their unreinforced counterparts and the improvements were proportional to the fiber volume fraction. In addition, both the unreinforced matrix as well as fiber reinforced composites were found to be stress-rate sensitive, but the extent of sensitivity observed was smaller than usually reported in the literature for cement-based materials under uni-axial tensile loading.