Deformation Characteristics of Rubber Waste Powder–Clay Mixtures

Abstract

With the increasing accumulation of rubber waste, the potential reuse of rubber fillers offers a promising solution to enhance the engineering properties of low-plasticity soils while promoting environmental sustainability. In this study, the effect of rubber waste powders (RWPs) on the consolidation and deformation properties of low-plasticity clay soil (CS) was investigated using a fully automated consolidation testing procedure for clay–rubber mixtures. The study involved adding 2% up to 30% RWPs to Tehran clay, and various parameters were evaluated through consolidation, compaction, and uniaxial strength tests. The results revealed that the consolidation volume of the mixture differed from that of the CS due to the elastic nature of the rubber wastes (RWs). To achieve higher precision, a new equation was proposed to determine the void ratio, along with modified e-log p’ curves for the clay–rubber mixture. Furthermore, the addition of RWPs to the CS resulted in moderated free swelling of the soil while enhancing ductility, compression index (Cc), swelling index (Cs), and recompression index (Cr). However, it was observed that the strength and modulus of elasticity of the mixture decreased with the increase in rubber content. Considering the variations in geotechnical parameters with different rubber contents, the appropriate rubber content can be selected based on specific applications in soil and rubber mixtures, considering the required geotechnical parameters. This study highlights the potential applications of RWPs as a material in civil and geotechnical engineering projects, providing valuable insights for sustainable and eco-friendly engineering practices.

Effect of Moisture Content and Wet–Dry Cycles on the Strength Properties of Unsaturated Clayey Sand

“…The roadbed filler of the Weihai-Yanhai segment of the Rongwu Expressway provided the soil specimens used in this investigation, which possess a particular density of 2.64 g/cm 3 , an ideal level of moisture of 12.5%, and a maximum dry weight of 1.79 g/cm 3 . Its distribution of particle sizes is displayed in Table 1.…”

“…Soils tend to deteriorate when subjected to wet-dry cycles or changes in moisture content. This has a direct impact on the roadbed pavement structure's strength, stiffness, and stability, which lowers the road's quality and lifespan [3]. The engineering properties of significant variations existed between the sand soil and clay and clayey sand [4].…”

“…The engineering properties of significant variations existed between the sand soil and clay and clayey sand [4]. However, according to the current engineering design standards, clayey sand is often regarded as sand for design, and some characteristics of the clay particles in the clayey sand are ignored, which will have a certain impact on the rationality, safety, and economy of road design [3].…”

“…Scholars have conducted numerous investigations to comprehend the impact of wet and dry cycles and moisture content on the engineering qualities of soils. And as the The roadbed filler of the Weihai-Yanhai segment of the Rongwu Expressway provided the soil specimens used in this investigation, which possess a particular density of 2.64 g/cm 3 , an ideal level of moisture of 12.5%, and a maximum dry weight of 1.79 g/cm 3 . Its distribution of particle sizes is displayed in Table 1.…”

“…Therefore, six groups of tests with different moisture content were set up, which were 6%, 8%, 10%, 12%, 14%, and 16%, respectively. The initial amount of moisture and the initial specimen's drying density were 12.5% and 1.71 g/cm 3 , respectively. The soil samples were sealed for 24 h after slowly air-drying or adding distilled water to the permeable stone to reach the target moisture content, followed by strength testing [5].…”