Residual Mechanical Properties of Fiber-Reinforced Lightweight Aggregate Concrete after Exposure to Elevated Temperatures

Chao-Wei Tang

doi:10.3390/app10103519

Abstract

In this study, the effects of individual and mixed fiber on the mechanical properties of lightweight aggregate concrete (LWC) after exposure to elevated temperatures were examined. Concrete specimens were divided into a control group (ordinary LWC) and an experimental group (fiber-reinforced LWC), and their compressive strength, elastic modulus, and flexural strength after heating to high temperatures of 400–800 °C were investigated. The four test parameters included concrete type, concrete strength, fiber type, and targeted temperature. The test results show that after exposure to 400–800 °C, the variation in mechanical properties of each group of LWC showed a trend of increasing first and then decreasing. After exposure to 400 °C, the residual mechanical properties of all specimens did not attenuate due to the drying effect of the high temperature and the more sufficient cement hydration reaction. However, after exposure to 800 °C, the residual mechanical properties significantly reduced. Overall, the mixed fiber-reinforced LWC showed a better ability to resist the loss of mechanical properties caused by high temperature. Compared with the loss of compressive strength, the flexural strength was relatively lost.

Highlights

Aggregates used in cement concrete are generally classified into three categories: light, normal, and heavy-weight
The results showed that, in general, steel fiber-reinforced concrete (SFRC) exhibited better residual mechanical properties than plain concrete when exposed to high temperatures and can more effectively prevent the risk of explosive spalling
The compressive strength, flexural strength, and elastic modulus of the concrete were tested according to the ASTM C39 [38], ASTM C78 [39], and ASTM C469 [40]

Summary

Introduction

Aggregates used in cement concrete are generally classified into three categories: light-, normal-, and heavy-weight. Lightweight aggregate (LWA) is a general term for natural or artificial aggregates with a bulk density less than 1200 kg/m3 [1]. Due to the increasing demand for LWAs and the unavailability of natural LWAs worldwide, techniques have been developed to produce them in modern factories [2]. LWA can be used to produce lightweight aggregate concrete (LWC) [1,2], which has a lower unit weight and can significantly reduce the cross-section of load-bearing members, thereby reducing the size of the foundation and making it more suitable for structural engineering [2,3]. Compared with normal weight aggregate concrete (NWC), LWC has practical advantages, such as good seismic performance, fire resistance, and durability [2]. LWC generally has higher brittleness and lower mechanical properties than NWC with the same compressive strength [4,5]

Methods

Results

Conclusion