Pozzolanic Effect of Fly Ash with Calcined Lime Sludge

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Title: Pozzolanic Effect of Fly Ash with Calcined Lime Sludge

Author(s): S. Maheswaran, A. Ramachandra Murthy, and G. N. Sakthi Priya

Publication: Materials Journal

Volume: 115

Issue: 6

Appears on pages(s): 925-934

Keywords: calcined lime sludge; fly ash; heat of hydration; hydrothermal reaction; microstructure; pozzolanic effect

Date: 11/1/2018

Abstract:
This study examines the pozzolanic effect of calcined lime sludge (CLS), a residual solid waste from the paper industry, and fly ash (FA), a residue generated from thermal power plants. CLS is obtained by calcination of lime sludge (LS) at the temperature 750 to 800°C (1382 to 1472°F) for 2 hours. The formation of calcium silicate hydrate (C-S-H), which is responsible for binding aggregates in concrete, is observed by hydrothermal method for three different proportions of CLS and FA in 1:5, 2:5, and 3:5 ratios at the temperature 220 to 250°C (428 to 482°F) in a hydrothermal cell. The chemical composition, physical properties, morphology, and mineralogical characteristics of the precursor materials and the formed C-S-H are analyzed by using XRF, XRD, SEM/EDS, TG-DSC, and FT-IR. In addition, the hydration behavior of ternary blended cementitious paste at a constant temperature of 30°C (86°F) is evaluated for pozzolanic activity by using ordinary portland cement (OPC), FA, and CLS in three different proportions. The result shows that the premature stiffening during early hydration of ternary blends compared to control. This study leads to potential use of FA and CLS in large quantities in a promising direction.