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Title: Unraveling the expansion mechanism in lightweight aggregates: Demonstrating that bloating barely requires gas
Authors: José Manuel Moreno-Maroto, Carlos Javier Cobo-Ceacero
Manuel Uceda-Rodríguez, Teresa Cotes-Palomino
Carmen Martínez García, Jacinto Alonso-Azcárate
Abstract: Lightweight aggregate bloating process has been studied by a simple experiment using an archetypal clay to know the actual amount of gas involved in expansion. Considering the relationship between gas loss (LOI) and volumetric changes over time, three main stages are identified: 1) a preheating stage of massive gas loss (close to 80% of the total) with hardly any volumetric change; 2) a very brief transition stage, in which sintering (shrinkage) and closed (micro)porosity formation begin, accompanied by a sudden gas loss (close to 100% of the total); 3) the bloating stage itself, in which an appropriate viscosity is reached, allowing the available residual gas (<0.1 wt%) to increase the aggregate volume due to the growth in size of the micropores formed in the transition phase and probably also to the development of new porosity. Therefore, the proportion of gas-generating components estimated to obtain a highly expanded lightweight aggregate would be much lower than previously thought: e.g., only 0.06 to 0.2% of carbonates (calcite or dolomite) or 0.2 to 1% of Fe2O3 would actually be involved in bloating. These results suggest that obtaining an adequate viscosity appears to be much more decisive for bloating than gas release capacity.
Keywords: Bloating
Expanded clay
Gas release
Lightweight aggregate
Issue Date: Jun-2020
metadata.dc.description.sponsorship: This research was conducted as a part of the SmartMats Project (MAT2015-70034-R), “Smart materials for sustainable construction”, funded by the Spanish Ministry of Economy and Competitiveness and FEDER (MINECO-FEDER). The authors gratefully acknowledge this support. The authors also gratefully acknowledge the technical and human support provided by CICT of the University of Jaén and the University of Málaga (UJA, MINECO, Junta de Andalucía, FEDER).
Publisher: ELSEVIER
Citation: José Manuel Moreno-Maroto, Carlos Javier Cobo-Ceacero, Manuel Uceda-Rodríguez, Teresa Cotes-Palomino, Carmen Martínez García, Jacinto Alonso-Azcárate, Unraveling the expansion mechanism in lightweight aggregates: Demonstrating that bloating barely requires gas, Construction and Building Materials, Volume 247, 2020, 118583
Appears in Collections:DIQAM-Artículos

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