Utilization of Class ‘C’ Fly Ash in Flexible Pavement System—A Review
Class C fly ash is a by-product of combustion of lignite or subbituminous coals having higher CaO content than Class F fly ashes. Class C fly ash possesses self-cementing properties; hence, its utilization as stabilizing agent for road material appears to be one of the most efficient solutions for dealing with critical problem of fly ash disposal. When clayey soils are stabilized with fly ash, mechanical properties of soil relevant to highway design and construction are found to be significantly improved. A review of literature for effect of use of Class C fly ash on California bearing ratio (CBR), resilient modulus (MR) and unconfined compressive strength (UCS) of soil is done and reported in this paper. With increase in fly ash content and curing period of soil samples, UCS, CBR and MR values for fly ash-treated soils are significantly improved when compared with those for untreated soils. These improved values on fly ash addition place the treated soils in the category of good to excellent for pavement base course, subbase course and subgrade applications. This paper also reviews some of the key advances in improving our understanding about clayey soils stabilized with Class C fly ash. The practical and research needs in order to enhance effectiveness of soil stabilization using Class C fly ash are addressed through discussion.
KeywordsClass C fly ash Flexible pavement Stabilization
- ASTM C618-17 (2017) Standard Specification for coal fly ash and raw or calcined natural pozzolan for use in concrete, ASTM International, West Conshohocken, PAGoogle Scholar
- Bergeson KL, Barnes AG (1998) Iowa thickness design guide for low volume roads using reclaimed hydrated Class C fly ash bases (No. ISU-ERI-Ames Report 98401), Engineering Research Institute, Iowa State UniversityGoogle Scholar
- Kang X, Ge L, Kang GC, Mathews C (2015) Laboratory investigation of the strength, stiffness, and thermal conductivity of fly ash and lime kiln dust stabilized clay subgrade materials. Road Mater Pavement Des, Taylor & Francis, 16(4):928-945Google Scholar
- McManis K. L., and Arman A. (1989) Class C fly ash as full or partial replacement for Portland cement or lime, Transportation Research Record 1219. Transp Res Board, Washington, DC, 68–81Google Scholar
- Puppala AJ (2016) Advances in ground modification with chemical additives: From theory to practice. Transp Geotech, Elsevier, 9:123-138Google Scholar