Material Properties of Crushable Concrete for use in Vehicle Anti-ram Barriers

Open Access
Author:
Doyle, Keith E
Graduate Program:
Civil Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 30, 2015
Committee Members:
  • Tong Qiu, Thesis Advisor
  • Aleksandra Z Radlinska, Thesis Advisor
  • Gordon Patrick Warn, Thesis Advisor
  • Zoltan Ivan Rado, Thesis Advisor
Keywords:
  • crushable concrete
  • polystyrene concrete
  • energy dissipation
  • confined testing
  • vehicle anti-ram barriers
Abstract:
The objectives of this research are to create a crushable concrete material that maximizes energy absorption and to characterize that material so that it can be modeled in full-scale crash test simulations. These objectives were fulfilled by performing a series of tests to determine the materials’ stress-strain behavior, strength and deformability in particular, under unconfined and confined conditions. In this study, multiple crushable concrete mixture designs containing partial and full replacement of aggregate by expanded polystyrene spheres were tested in unconfined and confined compression tests. Unconfined testing showed high ductility of polystyrene concrete, but the samples ultimately failed in shear. This shows that unconfined condition is not an efficient way to incorporate a crushable concrete element into a barrier. As such, it is recommended that crushable concrete is designed with adequate confinement (e.g., encapsulated element), to maximize energy dissipation in vehicle anti-ram barriers. Confined compression testing showed a much better comparison of the energy absorption characteristics of different mixtures. Changes in the water-to-cement ratio (w/c) and strain rate of loading were shown to have minimal effect at the levels that were tested. Increasing the amount of polystyrene replacement of aggregate, however, caused an increase in deformability but a decrease in strength. This tradeoff will define the process for determining a mixture design that optimizes energy dissipation for application-specific barrier design.