Use of fly ash to improve soils for road construction projects in Sri Lanka

Abstract

Sri Lanka is ambitiously pursuing for the massive infrastructure developments to meet the social demand and to foster economic growth. Construction highways and railways is a key focus area of the development effort. A considerable quantity of suitable soil which would be a major requirement for implementing such projects. In most of the cases, soils found near to the construction sites are rejected due to low California bearing ratio (CBR); although, they satisfy other parameters. Hence, engineers have to transport the suitable soil by hauling long distances incurring additional transport cost. If, locally available material can be improved, it would be the most beneficial solution to infrastructure developments. This study discusses the improvement of such rejected soils with fly ash from several construction sites in Sri Lanka. Fly ash is an abundantly available byproduct of the Norechchole Thermal Power plant. The basic soil tests such as particle size analysis, Atterberg limits, Proctor compaction and CBR tests were conducted on unimproved and improved soils. The CBR values of improved soils in different locations could be identified as increased with various percentage of soil with fly ash on weight basis. Mixing is proposed with a traditional conveyor belt mechanism. Use fly ash for infrastructure developments is to be motivated with objective in protecting environment by utilization of new alternatives and reducing the excessive dumping of fly ash to the environment.