Dissertation/Thesis Abstract

Mechanical and Durability Characteristics of Fly Ash Based Soil-Geopolymer Mixtures for Road Base and Subbase Layers
by Adhikari, Bikash, M.S., University of Louisiana at Lafayette, 2017, 148; 10287480
Abstract (Summary)

In this research study, high plastic and medium plastic soils were used in evaluating the physical and mechanical properties of fly ash-soil Geopolymer mixtures. Sieve analysis and Atterberg limit tests were conducted to classify the soil. Class F fly ash, an industrial byproduct, was used in the alkaline environment of a mixture of sodium silicate and various concentration of sodium hydroxide to prepare fly ash based Soil-Geopolymer mixtures. The modified proctor test was conducted to investigate the moisture-density characteristics of mixtures. Based on literature search and preliminary experiments, the experimental design matrix of was developed by using various combination of fly ash content, alkaline ratio, and concentration of sodium hydroxide. Several mixtures based on the experimental design matrix were compacted, cured at elevated temperature and tested for unconfined compressive strength.

Regression analysis was conducted to develop regression models to optimize and conduct sensitivity of the compressive strength in relation to mix variables of Soil-Geopolymer mixtures. Based on sensitivity analysis and UCS criteria recommended by DOTD Louisiana, two mixtures were selected for further evaluation along with Standard soil-cement mixtures. The resilience modulus, dynamic modulus, and durability test were conducted for selected Soil-Geopolymer mixtures and standard soil-cement mixtures, as recommended by LA DOTD.

The result of the study showed that the alkali activated soil-fly ash mixtures fulfilled the compressive strength criteria of cement treated design (CTD) and cement stabilize design (CSD) of 150 psi and 300 psi, as recommended by LA DOTD. Also, the results indicated that Soil-Geopolymer showed satisfactory performance under compressive strength test and dynamic loading tests. Further, the Soil-Geopolymer mixtures passed wet and dry durability test criteria. Based on mechanical and durability characteristics evaluated it can be recommended that Soil-Geopolymer mixtures studied in this study has an immense potential to be used as pavement subgrade, subbase, and bases.

Indexing (document details)
Advisor: Khattak, Mohmmad Jamal
Commitee: McManus, Kenneth, Sun, Xiaoduan
School: University of Louisiana at Lafayette
Department: Civil Engineering
School Location: United States -- Louisiana
Source: MAI 57/01M(E), Masters Abstracts International
Subjects: Civil engineering, Transportation
Keywords: Durability, Fly ash, Resilient modulus, Soil-cement stabilization, Soil-geopolymer, Unconfined compressive strength
Publication Number: 10287480
ISBN: 978-0-355-52068-2
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