title: Coal fly ash utilization: low temperature sintering of wall tiles.
abstract: We present here a study of the sintering of fly ash and its mixture with low alkali pyrophyllite in the presence of sodium hexa meta phosphate (SHMP), a complex activator of sintering, for the purpose of wall tile manufacturing. The sintering of fly ash with SHMP in the temperature range 925-1050 degrees C produces tiles with low impact strength; however, the incremental addition of low alkali pyrophyllite improves impact strength. The impact strength of composites with >or=40% (w/w) pyrophyllite in the fly ash-pyrophyllite mix satisfies the acceptable limit (19.6 J/m) set by the Indian Standards Institute for wall tiles. Increasing the pyrophyllite content results in an increase in the apparent density of tiles, while shrinkage and water absorption decrease. The strength of fly ash tiles is attributed to the formation of a silicophosphate phase; in pyrophyllite rich tiles, it is attributed to the formation of a tridymite-structured T-AlPO(4) phase. Scanning electron micrographs show that the reinforcing rod shaped T-AlPO(4) crystals become more prominent as the pyrophyllite content increases in the sintered tiles.
authors.affiliation: Regional Research Laboratory, Bhopal (CSIR), Habib Ganj Naka, Hoshangabad Road, Bhopal- 462026, India. navinchandrarrl@yahoo.com
authors.forename: Navin
authors.initials: N
authors.lastname: Chandra
authors.forename: Priya
authors.initials: P
authors.lastname: Sharma
authors.forename: G L
authors.initials: GL
authors.lastname: Pashkov
authors.forename: E N
authors.initials: EN
authors.lastname: Voskresenskaya
authors.forename: S S
authors.initials: SS
authors.lastname: Amritphale
authors.forename: Narendra S
authors.initials: NS
authors.lastname: Baghel
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry; D060729:Coal Ash; D003080:Cold Temperature; D003252:Construction Materials; D019563:Mechanics; D008855:Microscopy, Electron, Scanning; D052638:Particulate Matter / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D000538:Aluminum Silicates; D060729:Coal Ash; D052638:Particulate Matter; D010710:Phosphates; D014867:Water; C049037:aluminosilicate; D002244:Carbon; C009285:sodium polymetaphosphate