Comparison between Cement and Concrete Waste on the Strength Behaviour of Marine Clay Treated with Coal Ash

Norhidayah Abdul Hassan,Aminaton Marto,Ibrahim Izni Syahrizal,Ahmed Mohammed Awad Mohammed,Mohd Yunus Nor Zurairahetty,Nordiana Mashros,Nor Zurairahetty Mohd Yunus,Yaacob Haryati,Zuriana Haron,Nadiah Jamaludin,Mariana Aida Abdul Kadir

doi:10.1051/matecconf/201825001003

Abstract

This paper aims to compare the strength behaviour of demolished concrete material (DCM) and ordinary Portland cement (OPC) in addition to coal ash for stabilizing marine clay, thus determining the optimum mix. Coal ash with different ratio of bottom ash (BA) and fly ash (FA) were prepared at various percentages (i.e. 3%, 6% and 8%). In addition, limited amount of DCM and OPC of 2% was added at different curing periods of 0, 7 and 28 days respectively. Thus, the percentage of admixture added to the marine clay were 5%, 8% and 10% respectively. Unconfined compressive strength (UCS) test was done and the results revealed that the strength of treated marine clay soil increased significantly with increment percentage of coal ash and also for both DCM and OPC. For admixture with OPC, treated marine clay with 5% admixture shows the highest strength gained, while the effective combination between bottom ash and fly ash is 50:50. At the first 7 days the strength gain was very high but from 7 days to 28 days the gain of strength was reduced. While for DCM, 5% of additive at 30BA:70FA shows the highest strength. In addition, both OPC and DCM provide significant strength gained between 0-7 days and decrease for 7-28 days. In conclusion, when comparing both stabilizer, OPC is a much more efficient secondary stabilizer when reacted with coal ash. As it provide early gain in strength with a much higher strength.

Highlights

Generation of coal ash waste is increasing at alarming rate
The results from unconfined compressive strength (UCS) test are discussed over the strength of treated marine clay according to the percentage of additive, curing period and various proportion of coal ash other than compared with Unconfined compressive strength (UCS) untreated samples for both ordinary Portland cement (OPC) and demolished concrete material (DCM) stabilizer
DCM has a lower cement content which makes the strength of sample much lower than OPC

Summary

Introduction

Generation of coal ash waste is increasing at alarming rate It is predicted in International Energy Outlook 2009 that a projection of 88% increase is expected in coal combustion for countries such as United States, China and India between the year 2006 and 2030 [1]. The coal ash waste continues to increase to a rate of 131 million tons per year in United States[1]. Coal ash waste generated by Tanjung Bin power station itself produce 180 tonnes of bottom ash and 1620 tonnes of fly ash daily [6]. This shows that there is an abundance of coal ash waste waiting to be utilized. Due to the high costs in constructing coal ash ponds as a mean of dumping site, power plants’ authorities are finding new ways in order to explore the feasibility of beneficial uses of existing coal ash to cater for disposal of newly generated coal ash

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Conclusion