Characterization of Fly and Bottom Ashes Mixtures Treated using Sodium Lauryl Sulphate and Polyvinyl Alcohol

C.G Robert,A Ayob,P.Y Hong,M.E Razali,M.F Muhammad Zaki,E.V Lew,N Mohamed Noor,A.W Azhari

doi:10.1051/e3sconf/20183401018

Abstract

Malaysia promotes coal as an option for solid fuel in electric power generation. Demanding of electricity needs, therefore, has led to increase the coal consumption and thus producing more coal waste products. The disposal of coal waste ashes has been a main concern to power generation station due to the need of disposal sites and operational costs. This study investigates the composition of fly ash (FA) and bottom ash (BA) mixtures with difference component percentage treated with sodium lauryl sulphate (SLS) and polyvinyl alcohol (PVA) at 1.5 and 2.5 wt% solutions and examined in terms of specific gravity, pH, maximum dry density properties, and its surface morphology. Although the chemical composition of the SLS and PVA treated fly and bottom ashes studied in this current work is not altered extensively, significant changes could be observed in its physicochemical properties. Chemically treated fly and bottom ashes mixtures with SLS and PVA at 1.5 wt% solution exhibited specific gravity of 1.97 to 2.92 and high pH values within range of 9.28 to 10.52. The mixture of BA:FA=0:1 ratio depicting high maximum dry density of 1.35 to 1.56 g/cm3 in both SLS and PVA solutions at 1.5 and 2.5 wt%. Scanning electron microscopy image shows distinct surface morphologies of SLS-treated fly and bottom ashes mixture that the particles are packed closely, strongly bonded similar to popcorn shape due to the effect of active silanol groups acted on coal ashes surface with the presence of Al-O/Si-O/other oxides. These findings suggest that higher level of chemical interaction between the fly and bottom ashes particles, significantly enhances pozzolanic reactions such as shear strength, plasticity, cementing properties, and thus other engineering properties.

Highlights

Coal power plant which generates electricity consumed coal and producing residuals which are fly ash (FA) and bottom ash (BA)
These coal ashes treated with the sodium lauryl sulphate (SLS) or polyvinyl alcohol (PVA) solutions were placed in a stirrer with continuous shaking at 130 revolutions per minute
The small size of spherical fly ash particles gives to a better packing of aggregate materials, which decrease porosity, and significantly increase the compressibility and workability of fly-bottom ashes mixtures for further engineering application

Summary

Introduction

Coal power plant which generates electricity consumed coal and producing residuals which are fly ash (FA) and bottom ash (BA). The by-products ratio of coal combustion is 80% fly ash and 20% bottom ash [1]. It is estimated both chemically toxic ashes produced as much as 100 million tons in US in the year 1999 [2]. These most complex and abundant of anthropogenic materials, if not properly disposed of, can lead water and soil pollution, disrupt ecological cycles and pose environmental hazards [3]. Fly ash is mostly light, fine particle, spherical in shape and grey while bottom ash is heavy, coarse particles, angular and blackish. The chemical constituents of both two materials are very similar, with the major difference in their particle shape and size [5]

Methods

Results

Conclusion