Geotechnical properties of rice husk ash and coconut fiber stabilized soil and its performance evaluation as subbase material

Name: Domphoeun, Rithy

keyword: Laterite soil

; Rice husk ash

; Coir fiber

; Lime

; Compaction

; UCS

; CBR

; Direct Shear

; Flexural strength

Abstract: Thailand, as a tropical country, is subject to substantial rainfall and a high risk of floods. These floods can directly impact roads constructed with soil with engineering properties, necessitating the stabilization of such soil before allowing traffic. Laterite soil is commonly utilized for road construction in several provinces of Thailand, including Songkhla, Chumphon, Surat Thani, Trang, and Nakhon Si Thammarat. The Ministry of Natural Resources and Environment has indicated that the northeastern region has the highest quantity of lateritic soil. However, the majority of laterite soil exhibits poor engineering properties, failing to meet the requirements set by the Department of Highways in Thailand (DOH) for the use of subgrade or subbase materials in road construction. Soil stabilization refers to the process of improving the engineering properties of a soil to enhance its strength and durability. It involvesvarious techniques and materials, such as lime and cement, used to modify or treat soil, making it more suitable for construction purposes. In this study, the improvement of laterite soil replaced by RHA, lime, and coir fiber was investigated for use as a subbase pavement material. The laterite soil was replaced with 10%, 20%, and 30% rice husk ash (RHA) ; 0.5%,1%, and 1.5% coir fiber (CF) ; and 4% and 8% lime (L) were added to the dry mass of the soil. A compaction test was performed to obtain the maximum dry unit weight and optimum moisture content required to prepare different mix designs for the unconfined compressive strength (UCS), California bearing ratio (CBR), Durability, Direct Shear, and Flexural Strength tests. Based on the UCS results for the 7 and 28 days cured samples, mix designs with significant improvements were chosen for the other tests mentioned above. The results indicated an improvement in the strength of the laterite soil stabilized with RHA, lime, and CF. The mix design of 20% RHA and 8% lime showed the optimum strength of the UCS, CBR, direct shear, and durability. Similarly, the mix designs with 20% RHA, 8% lime, and 1% CF exhibited the highest flexural strength. Based on the stress-strain curves of the UCS test, the mix designs with higher strength exhibited more brittle behavior during failure. Nonetheless, the presence of coir fibers resulted in a more ductile behavior of the samples. Moreover, the flexural strength test showed that the inclusion of coir fibers prevented sudden failure of the specimen under high tensional stresses. The morphology and chemical characteristics of the materials were analyzed using Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), and X-ray fluorescence (XRF) tests. The SEM and EDX results indicated the presence of calcium silicate hydrate (C-S-H) gel on the surface of the soil particles, which resulted from the pozzolanic reaction of Rice Husk Ash (RHA) and Lime (L) after 56 days of curing.

Thammasat University. Thammasat University Library

Address: BANGKOK

Email: preserv@tu.ac.th

Name: Otaghsaraei, Amin Eisazadeh

Role: advisor

Name: Nishimura, Satoshi

Role: co-advisor

Created: 2023

Modified: 2024-10-22

Issued: 2024-10-22

วิทยานิพนธ์/Thesis

application/pdf

DOI: 10.14457/TU.the.2023.360

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Engineering and Technology

Grantor: Thammasat University

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