Soil-Cement Reinforced with Industrial and Biological Wastes for Civil Construction.

Abstract

This thesis examines the mechanical properties of soil–cement base materials (pavement) and the optimal ratio of cement, fly ash, bottom ash, polyethylene fibers, glass fibers, and chicken feathers to produce an environmentally friendly road material. The best proportions of these materials to be incorporated into soil–cement will be determined, as it is essential to define an environmentally friendly road material. In this investigation, the unconfined compression test was used. A liquid limit of 84–88% was maintained while mixing all soil–cement samples to investigate the strength development in Ordinary Portland Cement (OPC) and fly ash (FA) admixed Bangkok clay.The compressive strength of Bangkok soft clay was analyzed. The OPC was partially replaced by FA, which is a sustainable method since FA is an industrial waste product from the Mae Moh power plant in northern Thailand. Bangkok soft clay was mixed with OPC at 20% by weight and varied FA content from 0%, 10%, 15%, 20%, 25%, to 30% by weight. Samples were cured for 7, 14, 28, and 90 days.The initial shear modulus (G₀) was determined from the shear wave velocity (Vs), measured using a non-destructive bender element test. For comparison and validation of results, strength development was also evaluated using the destructive unconfined compression test (UCS). The results showed that the optimum FA replacement was approximately 15–20%, and strength development of Bangkok clay admixed with OPC and FA increased with curing time. Moreover, the research established a linear relationship between G₀ (MPa) and qᵤ (MPa) as G₀ = 27.57qᵤ. Additionally, the linear relationship between the normalized G₀/G₀(28) and qᵤ/q₂₈ was observed as G₀/G₀(28) = 0.9073qᵤ/q₂₈.In addition to OPC contents of 2%, 4%, 6%, 8%, and 10% by weight, polyethylene fibers were added at 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% by volume. These samples were cured for 7, 14, and 28 days and subjected to an unconfined compressive strength test. The results showed that the optimum cement content was 8% by weight, and the recommended polyethylene fiber content was 1% by volume. Furthermore, the novel high-strength polyethylene fiber with a diameter of 0.2 mm and a length of 6 mm provided the maximum UCS value.Different glass fiber volumes of 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% by volume, and lengths of 3, 6, and 12 mm were added to soil–cement. The OPC content was varied between 2%, 4%, 6%, 8%, and 10% by dry weight. Bottom ash content was varied from 5%, 10%, 15%, 20%, 25%, to 30% by volume. All soil–cement samples were cured for 7, 14, 28, 60, and 90 days. It was found that the optimum OPC content was around 8–10%, which aligns with the ACI 230.1R-09 standard requiring OPC content of 10–16%. The optimum fiber content was between 1.0% and 1.5%, with the best UCS result achieved using a glass fiber length of 12 mm. Finally, the optimum bottom ash content was 5–10%, and the recommended curing period should exceed 28–90 days.The unconfined compression strength test in this investigation was also conducted at a liquid limit of 84% while mixing soil–cement samples with chicken feathers an industrial waste at varying contents of 0.0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% by volume, and with OPC contents of 2%, 4%, 6%, 8%, and 10% by weight. After 28 days of curing, all soil–cement samples were tested according to the ACI 230.1R-09 standard. It was found that the recommended cement content for Bangkok soil–cement was 8%, and the optimal chicken feather fiber content was in the range of 0.5–1.0%.