Influence of red mud and waste glass on the microstructure, strength, and leaching behavior of bottom ash-based geopolymer composites

Abstract

The influence of waste glass and red mud addition as alternative source of aluminosilicate precursors on the microstructural, mechanical, and leaching properties of bottom ash-based geopolymer was studied in this work through mineralogical, morphological, and spectroscopic analysis, as well as by conducting compressive strength and leaching tests. The bottom ash-based geopolymer composites were synthesized by adding a constant amount of waste glass (10% by weight) and increasing amounts of red mud (up to 30% by weight). The results derived from FTIR, 29Si and 27Al MAS NMR, and SEM–EDX revealed that adding up to 10% (by weight) red mud to the synthesis mixes leads to an increase in the degree of geopolymerization of the activated mixes. The compressive strength followed the same trend. An increase of more than 10% (by weight) red mud added to the synthesis mixes results in a significant decrease of compressive strength of the geopolymer composites. A low leachability of geopolymer composites in regard with their contaminants was revealed especially for those with good compressive strength.

Synthesis and characterization of geopolymer from “In Natura” red mud and glass waste

“…On the other hand, the average values of the compressive strength increase as the SiO 2 /Al 2 O 3 molar ratio becomes higher. The result is consistent with Bobirica et al 49 . and Duxson et al., 7 who reported that the higher available reactive Si content largely increases the mechanical strength.…”

“…48 On the other hand, the average values of the compressive strength increase as the SiO 2 /Al 2 O 3 molar ratio becomes higher. The result is consistent with Bobirica et al 49 and Duxson et al, 7 who reported that the higher available reactive Si content largely increases the mechanical strength. The mixtures with SiO 2 /Al 2 O 3 theoretical molar ratio equal to 6 presented the best compressive strengths, indicating that the greater availability of silica may have contributed to the greater degree of geopolymerization.…”

Preparation and Strength Formation Mechanism of Calcined Oyster Shell, Red Mud, Slag, and Iron Tailing Composite Cemented Paste Backfill

“…Combined with the previous research results [ 29 , 30 ], we observed a sharp peak at 450 cm −1 for Si–O–Si and O–Si–O bending vibrations and a peak at 715 cm −1 attributed to the CPB sample Si–O–T (symmetric stretching vibrations in middle aluminosilicate composites). The C–O bending vibration at 870 cm −1 and the C–O asymmetric stretching vibration at 1470 cm −1 were observed to be the peak characteristics in calcite.…”

“…The degree of polymerization of the two gels presented different trends. Because the bond energy of Al–O is lower than that of Si–O [ 30 ], Al entered the amorphous material and participated in polymerization at the beginning of the reaction. Thus, the degree of aggregation was the highest at an age of 1 day.…”

Taguchi- Grey relational analysis for Optimizing the Compressive Strength and Porosity of Metakaolin-Based Geopolymer

“…Geopolymer materials have an advantage over the Portland cement-based binders which cause the emission of very large amounts of carbon dioxide. Fly ash, waste glass and slag were used as raw materials for the geopolymer which can decrease the carbon emission from these binder materials [3][4][5][6]. Metakaolin-based geopolymers are supposed as ''model-system" without the drawbacks inserted by using fly ash, slag, and other alternative starting materials which include several difficult-to-characterize amorphous phases [7].…”