Title: Fiber Reinforced Cement Based Composites Under Drop Weight Impact Loading: Test Equipment and Material Influences

Author(s): N. Banthia and V. Bindiganavile

Publication: Symposium Paper

Volume: 206

Issue:

Appears on pages(s): 411-428

Keywords: drop-weight test, fiber reinforced concrete, impact, polymeric fibers, size effect, steel fibers

DOI: 10.14359/12266

Date: 4/1/2002

Abstract:
Impact resistance of concrete remains to date one of its least understood properties. There are no standardized test methods and no meaningful comparisons can be made between results from various labs. This paper describes some of the issues at hand, and examines the response of plain and fiber reinforced concrete to impact loading through a multi-pronged investigation using instrumented drop weight impact tests. The study involved understanding the influence of machine specific parameters such as hammer mass and drop-height, specimen specific parameters such as specimen geometry and size and, several material related parameters including the type of fiber reinforcement. Amont the fibers investigated, particular attempt was made at comparing steel and polymeric fibers under varying rates of load application. It was found that machine parameters such as the hammer mass and drop height greatly influence the apparent resistance of concrete to impact and its apparent sensitivity to stress rate. Both flexural strength and thoughness factors were seen to exhibit a size effect under impact loading. In the case of fiber reinforced concrete, both plain and fiber reinforced concrete exhibited an increase in strength with strss-rate. In the case of poypropylene fiber, however, due to the viscoelastic nature of the fiber material, a much greater improvement in fracture energy absorption under impact loading was noted. This effect was so pronounced, that under very high concrete exceeded that of steel fiber reinforced concrete. The paper discusses the relevance of these data in designing structures under impact and blast loading, and identifies areas of further research.