Improvement in Predicting the Post-Cracking Tensile Behavior of Ultra-High Performance Cementitious Composites Based on Fiber Orientation Distribution

Myoung Choi,Gum-Sung Ryu,Kyeong-Taek Koh,Su-Tae Kang,Bang Lee

doi:10.3390/ma9100829

Abstract

In this paper, the post-cracking tensile behavior of Ultra-High Performance Cementitious Composites (UHPCC) was studied and an improved analytical model to predict the behavior depending on the fiber orientation distribution was proposed. Two different casting methods were adopted to estimate the influence of the casting method on the tensile behavior. The direct tensile test results showed that the post-cracking tensile behavior was considerably dependent on the casting method. The influence of the casting method was quantified by image analysis of the fiber distribution. The fiber orientation distribution obtained by image analysis may sometimes include considerable error according to the image resolution, which may cause inaccuracy when predicting the post-cracking tensile behavior based on the fiber orientation distribution. To overcome this dependency, the tensile bridging behavior by the fibers in UHPCC was simulated considering the obtained fiber orientation distribution as well as the number of fibers detected. The post-cracking behavior was then simulated by combining the bridging behavior and tension softening behavior of the matrix. The approach adopted in this study to simulate the post-cracking behavior of UHPCC showed good agreement with the experimental results.

Highlights

Ultra-High Performance Cementitious Composites (UHPCC), which is one of several major topics related to recent concrete technology, exhibit very high compressive strength over 200 MPa as well as excellent durability [1,2,3,4,5]
The number of fibers detected in an image is relatively accurate regardless of the image resolution, if an appropriate threshold value for detecting fiber is applied and the objects that might be misidentified as a fiber are removed. In view of these points, this paper proposes an analytical method to predict the post-cracking tensile behavior of UHPCC with improved accuracy by considering both the fiber orientation distribution and the number of fibers detected simultaneously from the image analysis technique
The post-cracking tensile behavior of UHPCC according to the fiber orientation distribution was examined and an improved analytical model for better prediction of the behavior distribution was examined and an improved analytical model for better prediction of the behavior depending on the fiber orientation distribution was suggested

Summary

Introduction

Ultra-High Performance Cementitious Composites (UHPCC), which is one of several major topics related to recent concrete technology, exhibit very high compressive strength over 200 MPa as well as excellent durability [1,2,3,4,5]. With the help of short steel fibers, the inherent brittleness of high strength concrete can be overcome and sufficient ductility can be obtained in both compression and tension. This results in a high tensile strength of more than 10 MPa in direct tension and 35 MPa or more in bending [6,7,8,9]. The modal expressions for the Materials 2016, 9, 829; doi:10.3390/ma9100829 www.mdpi.com/journal/materials

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Results

Conclusion