Mechanical, Fracture, and Microstructural Assessment of Carbon-Fiber-Reinforced Geopolymer Composites Containing Na2O.

Ahmad Rashedi,Riadh Marzouki,J Naveen,Nurul Fazita Mohammad Rawi,Ali Raza

doi:10.3390/polym13213852

Abstract

For a sustainable environment, geopolymer (GPO) paste can be used in the construction industry instead of Portland cement. Nowadays, sustainable construction and high-efficacy composites are demanding. Therefore, in the present investigation, the mechanical and microstructural efficacy of carbon-fiber-reinforced fly ash-based GPO with different percentages of nano-sodium dioxide (NS) were studied. The investigated percentages of NS were 0%, 1%, 2%, 3%, and 4%. For all the samples, the carbon fiber content was kept the same at 0.5% by weight. Different percentages of NS for all five fabricated GPO composite pastes were assessed with scanning electron microscopy (SEM). Various mechanical parameters of GPO—the compressive strength, toughness modulus, hardness, toughness indices, impact strength, fracture toughness, flexural strength, and elastic modulus—were evaluated. The results revealed that the use of 3% NS was the most effective for ameliorating the mechanical, microstructural, and fracture behavior of GPO. The use of 3% NS in carbon-fiber-reinforced GPO paste showed the maximum improvements of 22%, 46%, 30%, 40%, 14%, 38.4%, 50.2%, 31%, and 64% for the compressive strength, flexural strength, elastic modulus, toughness modulus, hardness, compressive stiffness, bending stiffness, fracture toughness, and impact strength, respectively. The SEM study showed that the inclusion of NS improved the microstructure and delivered a denser GPO paste by improving the interfacial zones and quickening the polymerization reaction.

Highlights

The early strength of GPO is reduced when prepared with fly ash, and it has limited use because of its brittle nature when the requirement is of flexural strength (FLS) capacity is high
The results showed that the presence of nano-sodium dioxide (NS) led to deflection improvements because of the arrangement of a fiber–lattice bond, but it decreased the diversion of all models because of the creation of a brittle composite
We obtained the maximum compressive strength (COS) value of carbon-fiber-reinforced GPO pastes, 22% in comparison to the GPO paste without NS, with 3% NS. This improvement may have resulted from the blocking of nanovoids and microvoids caused by the inclusion of NS, as well as the increased speed of the polymerization reaction

Summary

Introduction

Studies on the geopolymer (GPO) composites are in the spotlight of advanced research due to the high requirements for sustainable construction and high-efficacy composites [1,2]. Environmental pollution is increasing due to the high carbon footprint by-products of Portland cement production and the emission of 5% CO2 globally [3]. Due to outstanding efficacy in the construction pastes, geopolymers can be used instead of Portland cement [4,5,6,7]. To use them in construction, other modern techniques should be explored. The early strength of GPO is reduced when prepared with fly ash, and it has limited use because of its brittle nature when the requirement is of flexural strength (FLS) capacity is high. Other modern techniques should be explored to tackle this problem

Methods

Findings

Discussion

Conclusion