Experimental Study on Axial Compressive Performance of Polyvinyl Alcohol Fibers Reinforced Fly Ash-Slag Geopolymer Composites.

Shuhua Xiao,Jiaxiang Lin,Yongchang Guo,Ying Song,Yongjian Cai,Xuewei Lan,Guotao Liu

doi:10.3390/polym14010142

Shuhua Xiao, Jiaxiang Lin + Show 5 more

Open Access

https://doi.org/10.3390/polym14010142

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Abstract

Geopolymer concrete (GC) has been gaining attention in research and engineering circles; however, it is a brittle material with poor tensile performance and crack resistance. To address these problems, we introduced fibers into GC. In this study, axial compression and scanning electron microscope (SEM) tests were carried out on polyvinyl alcohol (PVA) short fiber reinforced low-calcium fly ash-slag-based geopolymer concrete (PFRGC). The ratio of PVA short fibers and low-calcium fly ash on the compression behavior of fiber reinforced geopolymer concrete (FRGC) were investigated and discussed. The test results show that PVA fibers play a bridging role in the cracks of the specimen and bear the load together with the matrix, so the addition of PVA fibers delayed the crack propagation of GC under axial compression. However, with the increase of low-calcium fly ash/PVA fibers, the number of unreacted fly ash particles in PFRGCs increases. Too many unreacted fly ash particles make GC more prone to micro-cracks during loading, adversely affecting compressive properties. Therefore, the axial compressive strength, elastic modulus, and Poisson’s ratio of GC decrease with the increasing low-calcium fly ash/PVA fibers.

Highlights

Global warming and climate change are mainly caused by carbon dioxide (CO2) emissions, which have become the focus of international attention [1,2]
The main reasons may be as follows: (1) fluidity of cementitious material and uniformity of internal materials were deteriorating with the exceeding polyvinyl alcohol (PVA) fibers volume ratio, which decreased the axial compressive strength of the specimens; (2) the geopolymer reaction is decreased with an excessive PVA fibers ratio as the hydrophilic PVA fibers absorbed a large amount of free water during the geopolymer reaction process, which led to more porosities and cracks and lower compressive strength of the specimens
This paper conducted quasi-static axial compression and scanning electron microscope (SEM) tests on PVA fibers reinforced fly ash-slagbased geopolymer concrete (PFRGC)

Summary

Introduction

Global warming and climate change are mainly caused by carbon dioxide (CO2) emissions, which have become the focus of international attention [1,2]. Axial compression test and scanning electron microscope (SEM) test were used to study the axial compression performance of PVA fibers reinforced fly ash-slagbased geopolymer concrete (PFRGC) specimens. The effect of the ratio of fly ash and PVA fibers on the failure mode, compressive strength, the stress–strain behavior, elastic modulus, and Poisson’s ratio were investigated and discussed. Because of the high content of Ca in slag, a certain amount of calcium aluminosilicate gel (C-(A)-S-H) can be formed when it is mixed into the silicon-rich aluminum raw material system.

Results and Discussions

Stress–Strain Curves

Elastic Modulus and Poisson’s Ratio

Conclusions