Preparation of geopolymeric materials from sewage sludge slag with special emphasis to the matrix compositions

Abstract

Solidification of SSS (sewage sludge slag) has been carried out by the geopolymer binder technique at 80°C steam conditions mixed with CFA (coal fly ash). Geopolymer liquor was prepared by mixing Na-disilicate solution of 1.27 S.G. (specific gravity) and 10 M NaOH solution in 3:1 proportion. Obtained monolithic materials were subjected to physical measurements such as 3-point flexural strength, bulk density and expansion-shrinkage. Subsequently, matrix as well as filler chemical compositions were analyzed by SEM-EDX. Results showed SSS is an active filler similar to CFA and maximal strength was reached by blending SSS with CFA in 1:3 proportion. P2O5 and CaO components of SSS strongly contributed to the polycondensation of the geopolymer liquor other than theoretically expected Al2O3 and SiO2 components.