Abstract

Ultra High Performance Fiber Reinforced Concrete (UHP-FRC) is relatively new cementitious material, which has been developed to enhance material performance such as, durability, workability and strength. UHP-FRC has an outstanding dynamic performance with high capacity to absorb damage. Because of its superior performance under dynamic loading, UHP-FRC has been induced in structures where dynamic resistance is required. It is proven that like other concrete materials, UHP-FRC strength increases significantly when subjected to high strain rates. The objective of this study is to develop understanding of strain rate sensitivity of UHP-FRC with 2% steel fiber by volume fraction and plain High Strength Concrete (HSC). Compressive and flexural tensile strength of each concrete composite were investigated to evaluate and compare their strain rate sensitivity through dynamic increase factor (DIF). The specimens were tested under six different strain rates; three in quasi-static and three in dynamic domain. Strain rates in quasi-static domain conducted by MTS test machine and strain rates in dynamic domain conducted using the drop hammer technique. The test results revealed that UHP-FRC exhibits less strain rate sensitivity while HSC show much higher rate sensitivity in comparison to other materials.

Highlights

  • Ultra-High Performance Concrete known as Ultra High Performance Concrete (UHPC) was initially known as reactive powder concrete (RPC) with a compressive strength over 150 MPa produced in bulk quantities, which have been in interest around the world since early 1990s [1]

  • This study revealed that there is no significant increase in shear strength at high strain rates

  • Compressive and flexural strength tests conducted at different strain rates for the evaluation of dynamic increase factor (DIF) of each composite

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Summary

Introduction

Ultra-High Performance Concrete known as UHPC was initially known as reactive powder concrete (RPC) with a compressive strength over 150 MPa produced in bulk quantities, which have been in interest around the world since early 1990s [1]. Despite of high compressive strength and durability, UHPC shows poor tensile and flexural strength which make it prone to cracking, and gradual increase of brittleness. Many researches developed to reveal that the mechanical characteristics of UHPC including high tensile strength and large ductility continues to develop even after cracking in cooperation with fibers [2]. From these studies, Ultra High Performance Fibre Reinforced Concrete (UHP-FRC) has merged. Compressive and flexural strength tests conducted at different strain rates for the evaluation of dynamic increase factor (DIF) of each composite. The compressive strength of each composite was recorded at 7, 14, 21, 28 and 56 day. It should be noted that, all the tests for HSC material were conducted after 56 days where material reached its maximum strength

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