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A platform for research: civil engineering, architecture and urbanism
Utilization of municipal solid waste incineration (MSWI) fly ash in blended cement. Part 1: Processing and characterization of MSWI fly ash
This paper is the first of a series of two articles dealing with the processes applied to MSWI (municipal solid waste incineration) fly ash with a view to reusing it safely in cement-based materials. Part 1 presents two stabilisation processes and Part 2 deals with the use of the two TFAs (treated fly ashes) in mortars. Two types of binder were used: an OPC (ordinary portland cement) containing more than 95 % clinker (CEM I 52.5R) and a binary blend cement composed of 70 % ground granulated blast furnace slag and 30 % clinker (CEM III-B 42.5N). In this first part, two stabilisation processes are presented: the conventional process, called 'A', based on the washing, phosphation and calcination of the ash, and a modified process, called 'B', intended to eliminate metallic aluminium and sulfate contained in the ash. The physical, chemical and mineralogical characteristics of the two TFA were comparable. The main differences observed were those expected, i.e. TFA-B was free of metallic aluminium and sulfate. The mineralogical characterisation of the two TFAs highlighted the presence of large amounts of a calcium aluminosilicate phase taking two forms, a crystalline form (gehlenite) and an amorphous form. Hydration studies on pastes containing mixed TFA and calcium hydroxide showed that this phase reacted with calcium hydroxide to form calcium aluminate hydrates. This formation of hydrates was accompanied by a hardening of the pastes. These results are very encouraging for the reuse of such TFA in cement-based materials because they can be considered as pozzolanic additions and could advantageously replace a part of the cement in cement-based materials. Finally, leaching tests were carried out to evaluate the environmental impact of the two TFAs. The elements which were less efficiently stabilised by process A were zinc, cadmium and antimony but, when the results of the leaching tests were compared with the thresholds of the European landfill directive, TFA-A could nevertheless be accepted at landfills for non-hazardous waste. The modifications of the process led to a significant reduction in the stabilisation of chromium, selenium and antimony.
Utilization of municipal solid waste incineration (MSWI) fly ash in blended cement. Part 1: Processing and characterization of MSWI fly ash
This paper is the first of a series of two articles dealing with the processes applied to MSWI (municipal solid waste incineration) fly ash with a view to reusing it safely in cement-based materials. Part 1 presents two stabilisation processes and Part 2 deals with the use of the two TFAs (treated fly ashes) in mortars. Two types of binder were used: an OPC (ordinary portland cement) containing more than 95 % clinker (CEM I 52.5R) and a binary blend cement composed of 70 % ground granulated blast furnace slag and 30 % clinker (CEM III-B 42.5N). In this first part, two stabilisation processes are presented: the conventional process, called 'A', based on the washing, phosphation and calcination of the ash, and a modified process, called 'B', intended to eliminate metallic aluminium and sulfate contained in the ash. The physical, chemical and mineralogical characteristics of the two TFA were comparable. The main differences observed were those expected, i.e. TFA-B was free of metallic aluminium and sulfate. The mineralogical characterisation of the two TFAs highlighted the presence of large amounts of a calcium aluminosilicate phase taking two forms, a crystalline form (gehlenite) and an amorphous form. Hydration studies on pastes containing mixed TFA and calcium hydroxide showed that this phase reacted with calcium hydroxide to form calcium aluminate hydrates. This formation of hydrates was accompanied by a hardening of the pastes. These results are very encouraging for the reuse of such TFA in cement-based materials because they can be considered as pozzolanic additions and could advantageously replace a part of the cement in cement-based materials. Finally, leaching tests were carried out to evaluate the environmental impact of the two TFAs. The elements which were less efficiently stabilised by process A were zinc, cadmium and antimony but, when the results of the leaching tests were compared with the thresholds of the European landfill directive, TFA-A could nevertheless be accepted at landfills for non-hazardous waste. The modifications of the process led to a significant reduction in the stabilisation of chromium, selenium and antimony.
Utilization of municipal solid waste incineration (MSWI) fly ash in blended cement. Part 1: Processing and characterization of MSWI fly ash
Aubert, J.E. (author) / Husson, B. (author) / Sarramone, N. (author)
Journal of Hazardous Materials ; 136 ; 624-631
2006
8 Seiten, 6 Bilder, 4 Tabellen, 32 Quellen
Article (Journal)
English
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