The mix and in-situ test results of coal ash CLSM


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Title: The mix and in-situ test results of coal ash CLSM

Author(s): Lih-Wen Quo, Jan-Cyuan Syu, San-Der Chyou, R. B. Zen and Hui-Jen Chiu

Publication: TCI Concrete Technology

Volume: 5

Issue: 4

Appears on pages(s): 61-70

Keywords: bottom ash, CLSM, coal ash, compressive strength, fly ash

Date: 10/20/2011

Taiwan Power Company (TPC) annually produces around 2 million tons of coal ash. Among them, fly ash occupies around 80% and bottom ash 20%. Most of the fly ash have been utilized as a kind of resources, however, most of the bottom ash are unusable as they are treated by sea-water and therefore, they are dumped into ash ponds. Recently, fresh water has been adopted to substitute sea water by parts of power plants to treat bottom ash so that the development of available approaches for bottom ash utilization becomes urgent. Because the dark-colored fly ash produced by TPC is hard to sell and it usually dumped at ash pond that shortens the service life of ash pond. The controlled low strength material (CLSM) containing dark-colored fly ash and bottom ash is developed and applied to the construction of pipeline trench backfill. Such an application not only promotes the resource utilization of coal ash, but also solves the soil settlement problem in the construction of pipeline trench backfill for TPC. The test results of this study indicate that coal ash from TPC is much suitable for the construction of pipeline trench backfill. As to the mixture design of CLSM, 1100 kg/m3 coal ash and 100 kg/m3 cement are typically used. If higher early strength is required, 20 kg/m3 of accelerating admixture without chloride is can be added. The CLSM mixture has flow spread greater than 20 cm and 28-day strength of 60 kg/cm2. In addition, The CLSM mixture has superior permeability as well as abrasion resistance to normal CLSM. The above-mentioned mixture has been applied to the demonstration constructions of pipeline trench backfill in Taichung and Kaohsiung city, resulting in excellent engineering properties.
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