Study of stress–strain and volume change behavior of fly ash-GBFS based geopolymer rammed earth

2021 ◽  
Author(s):  
Vahab Toufigh ◽  
Mohammad Hossein Karamian ◽  
Saeid Ghasemalizadeh
Keyword(s):  
Fly Ash ◽  
Volume Change ◽  
Rammed Earth ◽  
Stress Strain ◽  
Change Behavior ◽  
Volume Change Behavior

scholarly journals Optimization of Soil to Fly-Ash Mix Ratio for Enhanced Engineering Properties of Clayey Sand for Subgrade Use

2020 ◽  
Vol 10 (20) ◽  
pp. 7038
Author(s):  
M. A. Karim ◽  
Ahmed Sami Hassan ◽  
Adam Kaplan
Keyword(s):  
Fly Ash ◽  
Volume Change ◽  
Ash Content ◽  
Engineering Properties ◽  
Dry Density ◽  
Maximum Dry Density ◽  
Clayey Sand ◽  
Curing Period ◽  
Change Behavior ◽  
Volume Change Behavior

A laboratory investigation was carried out to determine the optimum soil to fly ash mix ratio to enhance the engineering properties of clayey sand that can potentially be used as a road subgrade. Grain size distribution and Atterberg limits tests were conducted to classify the soil and to study the effects of the fly ash on the soil plasticity. The Proctor test was conducted to determine the optimum moisture content and maximum dry density of soil-fly-ash mixtures with arbitrarily selected 0%, 40%, 50%, and 60% fly ash content. A higher percentage was selected to find the highest optimum fly ash content to maximize the beneficial use. Unconfined compression and consolidation tests were conducted with air-dry arbitrarily selected curing periods of 0, 2, 8, and 28 days to determine the strength and to predict the settlement and the volume change behavior. It can be concluded from the trend analysis that a fly ash content range of 32–50% appeared to be optimum that is expected to perform better as subgrade materials for a curing period range of 16–19 days. However, experimental data showed a fly ash content of 50% was the optimum for a curing period of 8 days. The settlement and the volume change behavior improved at least 44% with increased fly ash content.

Improvement of Strength and Volume-Change Properties of Expansive Clays with Geopolymer Treatment

2021 ◽  
pp. 036119812110018
Author(s):  
Rinu Samuel ◽  
Anand J. Puppala ◽  
Aritra Banerjee ◽  
Oscar Huang ◽  
Miladin Radovic ◽  
...  
Keyword(s):  
Volume Change ◽  
Carbon Dioxide Emissions ◽  
Expansive Soils ◽  
Linear Shrinkage ◽  
Plasticity Index ◽  
Specimen Preparation ◽  
Expansive Clays ◽  
Change Behavior ◽  
Volume Change Behavior ◽  
Lower Carbon

Expansive soils are conventionally treated with chemical stabilizers manufactured by energy-intensive processes that significantly contribute to carbon dioxide emissions globally. Geopolymers, which are synthesized from industrial byproducts rich in aluminosilicates, are a viable alternative to conventional treatments, as they are eco-friendly and sustainable. In this study, a metakaolin-based geopolymer was synthesized, and its effects on the strength and volume-change behavior of two native expansive soils from Texas, with a plasticity index over 20 were investigated. This paper elaborates on the geopolymerization process, synthesis of the metakaolin-based geopolymer, specimen preparation, and geopolymer treatment of soils. Comprehensive material testing revealed two clays with a plasticity index over 20. They were each treated with three dosages of the metakaolin-based geopolymer and cured in 100% relative humidity for three different curing periods. The efficiency of geopolymer treatment was determined by testing the control and geopolymer-treated soils for unconfined compressive strength (UCS), one-dimensional swell, and linear shrinkage. Field emission scanning electron microscope (FESEM) imaging was performed on the synthesized geopolymer, as well as on the control and geopolymer-treated soils, to detect microstructural changes caused by geopolymerization. A significant increase in UCS and reduction in swelling and shrinkage were observed for both geopolymer-treated soils, within a curing period of only 7 days. The FESEM imaging provided new insights on the structure of geopolymers and evidence of geopolymer formation in treated soils. In conclusion, the metakaolin-based geopolymer has strong potential as a lower-carbon-footprint alternative to conventional stabilizers for expansive soils.

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