Mechanical stabilisation of peat and clayey sand by using shraded tyre waste

Abstract

Weak soil, such as clayey sand and peat soil portray the characteristics of low bearing capacity, shear strength and permeability, high water content and compressibility, which are unsuitable to be the foundation of structure and pavement subgrade. Differential settlement and structural cracks will be most likely to occur when construct a structure on these types of soil. Thus, soil stabilisation introduces mechanical treatment to improve the properties and performance of the weak soils and achieve the desired soil stability by mixing with stabiliser. On the other hand, the need of treating the ground which is peat and clayey sand for construction as well as using scrap materials for stabiliser which can reduce environmental pollution and economic shall be considered. Therefore, this study performs to characterise the strength and performance of clayey sand and peat soil incorporate with waste rubber tyres and identify the optimum percentage of rubber tyres for soil enhancement. Clayey sand and peat soil were mixed with 0%, 5%, 10% and 15% of rubber tyre by the weight of the soil sample in each testing standard prior to conduct several laboratory experiments, such as physical properties test, for example, sieve analysis, hydrometer, pycnometer and Atterberg limit test. Also, several tests were conducted to determine the mechanical properties of modified soils, like moisture content test, consolidation test, standard Proctor compaction test and California bearing ratio test. The results showed that addition of stabiliser reduced the liquid limit, plasticity index and specific gravity of both soils. Subsequently, the moisture content of peat soil was 70.9% higher than clayey sand. Increased in the percentage of rubber tyre up to 10% and 15% revealed an improvement in the CBR value and settlement value of clayey sand, respectively. The CBR value was improved by 65% and addition of 50kN/m2 load to the CRT15 sample showed a lower settlement occurred than the parent soil. In contrast, the alteration of strength and settlement of peat-rubber tyre mixture did not give satisfactory results where it reduced the CBR value and increased the settlement thickness when more rubber tyre were included. Therefore, this research anticipated that rubber tyre can alter the strength and performance of clayey sand to meet the desired requirements of civil engineering construction, such as for ground foundation and pavement subgrade.