Abstract
Norochcholai coal power plant is the largest coal power plant in Sri Lanka and during the combustion of coalit annually generates about 250,000 metric tons of coal ash which consists of fly ash (FA) and bottom ash (BA). Almost all the generated ash is disposed into ash dumps except a small quantity of FA (30%) that is effectively utilized. Therefore, use of coal ash for construction purposes will offer a sustainable solution for reducing its by-products and overcoming the scarcity of raw materials required for construction work. The main aim of this research was therefore to determine the geotechnical engineering properties of FA and BA to find out the feasibility of using them as light weight embankment or backfill material. A series of laboratory experiments were conducted on FA, BA and FA-BA co-mixed samples to determine their particle size distribution, specific gravity, index properties, compaction characteristics, shear strength parameters and California bearing ratio (CBR). The experimental results reveal that the particle size of coal ash (FA and BA) is predominantly silt sized while containing some sand-sized fractions as well. This coal ash has a low maximum dry density (MDD) and a high optimum moisture content (OMC) compared to typical granular soils used in embankments. In addition, this ash has a higher friction angle and higher cohesion than most types of construction fills. Thus, both FA and BA can be used as light weight embankment or back fill material in civil engineering construction work.
Highlights
Lakvijaya coal power plant in Norochcholai is the largest coal power plant in Sri Lanka
Coal ash produced in the Lakvijayaplant can be used to meet this requirement which will provide a sustainable solution because of its advantages: (1) its byproducts can be used in construction and this will eliminate the land pollution problems associated with dump yards and reduce the
The higher void content in fly ash (FA) could limit the buildup of pore pressure during compaction, which allows it to be compacted over a larger range of water content [9]
Summary
Lakvijaya coal power plant in Norochcholai is the largest coal power plant in Sri Lanka. The power generated by this power plant meets about 50% of the daily electricity requirement of Sri Lanka. Land where ash could be dumped is scarce and the dust emitted by the already dumped ash spreads to nearby settlements. There is a scarcity of natural resources, especially fine aggregates, required for construction purposes. This has caused a shortage of backfill material and lightweight embankment material required for construction work. Coal ash produced in the Lakvijayaplant can be used to meet this requirement which will provide a sustainable solution because of its advantages: (1) its byproducts can be used in construction and this will eliminate the land pollution problems associated with dump yards and reduce the
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