Effect of class F fly ash on fine sand compaction through soil stabilization

Effectiveness study for fly ash cement improved marine clay

Thermal power stations in most countries are burdened with the problem of fly ash disposal, and unless suitable uses are found for fly ash, it will pose a gigantic problem for the power sec...

State-of-the-Art Review on the Role of Fly Ashes in Geotechnical and Geoenvironmental Applications

The use of recycled bassanite and coal ash to enhance the strength of very soft clay in dry and wet environmental conditions

Soil stabilization has become the major issue in construction engineering and the researches regarding the effectiveness of using industrial wastes as a stabilizer are rapidly increasing. This paper briefly describes the suitability of the local fly ash to be used in the local construction industry in a way to minimize the amount of waste to be disposed to the environment causing environmental pollution. Several civil engineering laboratory tests are conducted to study the geotechnical properties of fly ash and strength gain when mixed with local clay sample. A different proportion of fly ash and soil sample cured for 7 days results in a strength gain. A better understanding of the properties of fly ash is gained from the study and the tests indicates an improved strength and better properties of soft soil sample when stabilized. ivil engineering projects located in areas with soft or weak soils have traditionally incorporated improvement of soil properties by using cement and lime. Use of fly ash as a ground improvement soil admixture, when found viable, will be effective in terms of cost and a good approach to the environment to preserve and minimize accumulation of industrial waste. This study is performed to obtain geotechnical properties of fly ash for its application in the stabilization of soft soil. The geotechnical properties of fly ash will be evaluated with various laboratory tests to investigate the feasibility of using fly ash in soft soil stabilization. Constructions over soft soil are one of the most frequent problems in many parts of the world. The typical approach to soil stabilization is to remove the soft soil, and substitute it with a stronger material of crushed rock. Due to substantial cost of replacement, alternative methods to the problems are assessed. The study of using coal combustion residues, fly ash, is carried out to observe the effectiveness of its addition on stabilization of soft soil. This is one of the approaches to overcome the increasing amount of solid waste generated by the population. As land is a very valuable commodity and landfills are fast diminishing, the disposal of the ash generated from solid waste incineration poses increasingly difficult problems for the municipalities. A practicable solution to the disposal problems would be the reuse of solid waste ash for civil engineering applications. A research study of the geotechnical properties of the incinerator fly ash derived from solid waste incineration is investigated. The objectives of the study are to determine the geotechnical properties of fly ash and to investigate the effects of fly ash addition for strength of stabilized soft soil. Scope of this study is to analyze the consequences of the application of fly ash in soft soil stabilization. It covers methods for determining the geotechnical properties of fly ash to assess its suitability for soft soil stabilization. The fly ash is taken from Sejingkat Thermal Plant, Kuching.

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Geotechnical Properties of Fly Ash and its Application on Soft Soil Stabilization

The combustion of subbituminous coals in electrical generating units produces a fly ash that has proven benefits for the construction industry. Fly ash consists of the inorganic material within the coal that has been fused during combustion, solidified while suspended in the exhaust gases and collected by electrostatic precipitators. Bituminous coals have low concentrations of calcium compounds and the ash produced (Class “F”) exhibits no self-cementing characteristics. The addition of activators such as lime yields cementitious products so that this material can be used for a wide range of soil stabilization applications. Subbituminous coals have higher concentrations of calcium carbonate (CaCO3); thus, the ash (Class “C”) produced during combustion is rich in calcium, resulting in the self-cementing characteristics. Since Class “C” fly ash is self-cementing; activators such as lime or Portland cement are not required. Upon exposure to water, Class “C” fly ash hydrates forming cementitious products similar to those produced during the hydration of Portland cement. This property makes the self-cementing fly ash a very effective and economical stabilization agent for use in variety of construction applications.

Scott M. Mackiewicz

Papers

Stabilization of Soil with Self-Cementing Coal Ashes