TITLE:
Comparative Characteristics of Hydrated Lime with Fine Sewage Sludge Ash (FSSA) and Coal Fly Ash (CFA)
AUTHORS:
Mamoudou Sall, Abdou Ciss Wade, Gora Dieye, Alassane Traoré, Prince Momar Gueye, Prince Momar Gueye, Saliou Diouf, Déthié Thiaw, Khalifa Ababacar Diop, Djibril Diop
KEYWORDS:
Coal Fly Ash, Fine Sewage Sludge Ash, Lime, Binder, Microstructure, Thermomechanical Behavior
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.10 No.5,
September
29,
2022
ABSTRACT: The disposal of waste has become an environmental issue due to the limited available landfilling space. This paper aims to compare the characteristics of hydrated lime with fine sewage sludge ash (FSSA) and coal fly ash (CFA). Multiple techniques, X-ray fluorescence (XRF), X-ray diffraction (XRD), the Fourier transform infrared (FTIR), compressive strengths, thermophysical properties, and setting time were used to assess the physicochemical characteristics of the lime-based materials. X-ray fluorescence and X-ray diffraction were used to determine the chemical composition and phases of ashes, lime and binders. The results showed that the chemical composition of ashes is similar to that of cement. Besides glass, the main minerals identified in CFA and FSSA are quartz (SiO2) and anhydrite (CaSO4). Moreover, calcium aluminium oxide (Ca3Al2O6) was detected for CFA and phosphorus calcium silicate (Ca2SiO4-Ca3(PO4)2) for FSSA and minor phases were detected for both. FTIR measurements were carried out to characterize the inorganics components of different samples. Compressive strengths of mortars with different formulations have shown that both have a long-term positive effect which might be related to a pozzolanic activity. For the CFA the L3 binder consisting of 60% of coal fly ash and 40% lime has a higher compressive strength than the others while for the FSSA the L4 binder consisting of 80% fine ash and 20% lime has a higher compressive strength than the others. Both binders setting start times are greater than that of cement but shorter than that of lime. The study of the thermophysical properties of binders shows that they have a higher thermal resistance than cement mortar. Moreover, binders heat up less quickly because of their low effusivity compared to cement. Lime-based materials system could be a promising option to both relieve the waste disposal pressure and provide a potential sustainable construction material.