Use of pulverised and fluidised combustion coal ash in secondary road construction

Abstract

The research presented herein was undertaken to examine the viability of pulverised coal combustion (PCC) fly ash and fluidised bed combustion (FBC) spent bed, as a primary cementitious material and a secondary fine aggregate, respectively, for production of mixtures suitable for low-volume county and other secondary roads. To achieve the stated objective, the mechanical properties of a number of previously identified optimum PCC/FBC composites were studied in the laboratory and field. The characteristics such as unconfined uniaxial compressive strength, splitting tensile strength, modulus of elasticity and Poisson's ratio, absorption, resistance to freezing and thawing, and length change were investigated. Results conclude that the engineering properties of the PCC/FBC composites exceed those of the conventional mixes used in secondary roads. The field results reaffirm that the engineering characteristics of the laboratory mixtures can be easily attained in field. The suggested thickness design requirements are conservative when the 90-day strength of the PCC/FBC composites is considered.

Keywords:

• by-products
• secondary roads
• elastic modulus
• freezing
• sulphate attack
• thickness

Acknowledgements

This research was funded by the Office of Coal Combustion Residues Management Program (CCRM) through grants (No. 6-23428) made possible by the Illinois Department of Energy and Natural Resources (IDENR) and Illinois Clean Coal Institute (ICCI). However, any opinions, findings, conclusions or recommendations expressed herein are those of the author and not necessarily reflect the views of IDENR, ICCI and the CCRM. Thanks are extended to a number of manufacturers who contributed materials used in this project.