Material Characterization of Fiber Reinforced Concrete for Improved Blast Performance

摘要

The U.S. Army Engineer Research and Development Center (ERDC) is currently conducting material research on advanced cementitious composites with randomly distributed fiber reinforcement. The successes of the research are well documented, and unconfined compressive strengths on the order of 200 MPa are not uncommon. However, as with most cementitious materials, these materials exhibit a brittle tensile failure response. To improve the material's response to blast and ballistic loads, the tensile capacity must first be quantified and subsequently enhanced. This paper presents findings of three laboratory experimental series conducted to characterize, quantify, and enhance the tensile failure response of a new rapid-set, field-curable geopolymer concrete that offers distinct advantages over other cementitious composites. Individual fiber, single fiber pull-out, and direct uniaxial tension experiments were conducted for a geopolymer concrete capable of achieving 44 MPa in 24 hours, and 62 MPa in 28 days in ambient temperatures with no additional curing requirements. Three fiber types were examined at various embedment lengths in the matrix. Load versus displacement curves are presented for each type of fiber, as well as the mechanical properties of the fiber itself. Direct tension samples were cast with each type of fiber at 2% by volume in the matrix and tested in a direct uniaxial experiment. The corresponding load versus displacement responses are presented and discussed. Key steps are identified for ongoing research to optimize the fiber matrix interaction, thus maximizing ductility for enhanced material response to tensile forces.