Workability Properties of Concrete using Alum Sludge and Limestone Dust as Replacement of Fine Aggregate.

Workability is a function of the rheological properties of concrete which consist of stability, consistency and compatibility, it is also attributed to the physical property of a newly mixed concrete that determines the homogeneity at which a mix will be placed in form and finished without segregation of the individual materials. This paper presents an experimental work of ongoing research on the effect of two different industrial waste filler (treated alum sludge filler and limestone dust filler) on the workability of normal concrete. The alum sludge waste used in this study was waste from drinking water treatment plant. Both fillers were crushed and sieved to achieve a particle size of 45μm that was used to replace fine aggregate in different percentages 5, 10 and 15. This study was carried out in order to find the definite effect or behaviour of the two filler material on the workability of fresh concrete when used as a replacement of natural fine aggregate. Reduction in workability was observed from 10 to 15% replacement when alum sludge filler was employed in the mix, whereas limestone dust filler had better workability performance than the alum sludge. It was concluded that the addition of 400⁰C treated alum sludge with 5% replacement of fine aggregate yield similar workability behaviour with control mix and addition of 400⁰C treated alum sludge filler with 5 to 10% replacement content of fine aggregate in terms of the workability of fresh concrete is ideal and feasible to employ in concrete. Furthermore, the replacement of fine aggregate with limestone dust filler improved the workability of fresh concrete in all parameters of testing. Thus all percentage replacement content of limestone dust filler showed superior improvement in the concrete workability and said to be a good filling material for concrete when compared with the alum sludge filler. [ABSTRACT FROM AUTHOR]