Mechanical and Microscopic Properties of Graphite/Laterite Nanocomposites

Yuhao Gao,Xu Sun,Jianzhong Li,Yuxin Zhang,Leiyong Yang,Gianfranco Carotenuto

doi:10.1155/2021/1175621

Abstract

The effectiveness and improvement mechanism of graphite nanoparticles (GN) in strength properties and microstructure characteristics of regional laterite were analysed in this study. Dry density was also taken into consideration, and the effects of graphite nanoparticle (GN) content and dry density were mainly addressed. Triaxial tests, consolidation tests, and penetration tests were used to analyse the effectiveness of different dry densities and graphite nanoparticle mass ratios on the properties of laterite; microscopic methods such as scanning electron microscopy (SEM) tests were used to analyse the improvement mechanism. The results show that the increase in dry density can make the laterite more compact. The large specific surface area and nanoeffects of the graphite nanoparticles (GN) induce the attraction between soil particles after mixing, both of which make the laterite’s shear strength; compression index and impermeability have been enhanced to varying degrees. The microscopic tests showed that, as the content of graphite nanoparticles (GN) continues to increase, when it exceeds 1.0%, the attraction between soil particles increases and coarse particles are formed, which leads to the increase of the pores of the soil. In addition, the graphite nanoparticles have a certain degree of lubricity, a high amount of graphite nanoparticles enters the laterite soil layer, increasing the distance and gap between the layers, making it easy to separate the coarse particles from the coarse particles, and the strength increase is reduced. However, it is still stronger than that of the plain laterite.

Highlights

Laterite is a brownish yellow and brown regional special clay formed by physical and chemical weathering of carbonate rocks under humid and warm subtropical climate [1,2,3,4], which is widely distributed in Guangxi Zhuang Autonomous Region in southern China [5, 6]
When the graphite nanoparticles (GN) content is at the same level, the relationship between principal stress difference and axial strain of triaxial consolidated undrained test are shown in Figures 4(a)–4(c) and Figures 4(e)–4(g). e figures show that the dry density has a certain influence on the stressstrain curve of GN-laterite, which is mainly manifested in that the principal stress difference increases with the axial strain, and the relationship curve (M 1.0%) presents different forms due to the influence of dry density
When the dry density is at the same level, the relationship between principal stress difference and axial strain of triaxial consolidated undrained test shows that the GN content has a certain influence on the stress-strain curve of laterite, which mainly shows that the relationship curve presents different forms with the increase of axial strain (Figures 4(b), 4(d), 4(f ), and 4(h))

Summary

Introduction

Laterite is a brownish yellow and brown regional special clay formed by physical and chemical weathering of carbonate rocks (or rocks rich in iron, silicon, and alumina) under humid and warm subtropical climate [1,2,3,4], which is widely distributed in Guangxi Zhuang Autonomous Region in southern China [5, 6]. It has important research significance to improve the properties of laterite Traditional admixtures such as fly ash [23,24,25], lime [26, 27], and cement [28, 29] are used to improve the swelling, permeability, and mechanical strength of clay, while there are engineering problems with poor improvement effects such as slow growth of strength, easy cracking, and poor water stability [30,31,32] in practical application. E addition of graphite improves tensile cracking and expansion potential of bentonite, improving its strength [57] It can enhance the unconfined compressive strength and shear strength of the compacted clay [58], as well as yield strength and hardness of alloy [59]. This study added the admixture of graphite nanoparticles (GN) to the laterite, took a series of consolidated undrained triaxial tests, standard consolidation tests, variable head penetration tests, and scanning electron microscopy (SEM) tests to further study the influence of dry density and GN on the material composition, mechanical properties, and microstructure of laterite, as well as the microscopic mechanism that causes changes in the mechanical properties of laterite

Materials

Experimental Investigations

99.9 Flake powder

Results and Discussion

Conclusions