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Hattaf R, Aboulayt A, Lahlou N, Touhami MO, Gomina M, Samdi A, Moussa R. Effect of phosphogypsum adding on setting kinetics and mechanical strength of geopolymers based on metakaolin or fly ash matrices. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023:10.1007/s11356-023-27861-x. [PMID: 37291350 DOI: 10.1007/s11356-023-27861-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 05/19/2023] [Indexed: 06/10/2023]
Abstract
Our study aims to highlight the effects of the addition of phosphogypsum on certain fresh and hardened characteristics of geopolymer matrices based on metakaolin or fly ash. In the fresh state, workability and setting were studied by rheology and by the electrical conductivity measurement. The hardened state was characterized by XRD, DTA, SEM, and compressive strength measurement. Workability investigations reveal that the addition of phosphogypsum increases the viscosity, which limited the phosphogypsum addition rate to 15 wt% for metakaolin-based matrices and 12 wt% for fly ash-based matrices, with a setting retarding effect in both cases. Analyses of the matrices show dissolution of gypsum along with formation of sodium sulfate and calcium silicate hydrate. Moreover, the introduction of phosphogypsum to these matrices up to a mass rate of 6% has no significant effect on the mechanical strength. Beyond that rate, the compressive strength drops from a value of 55 MPa for the matrices without addition down to 35 MPa and 25 MPa when the addition rate is 12 wt% for the metakaolin-based and fly ash-based matrix, respectively. This degradation seems to be due to the increase in porosity created by addition of phosphogypsum.
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Affiliation(s)
- Rabii Hattaf
- Laboratory of Interface Materials and Environment, Faculty of Sciences Aïn Chock, University Hassan II Casablanca, 53306, Casablanca, Morocco.
| | | | - Nouha Lahlou
- Laboratory of Mechanics, Faculty of Sciences Aïn Chock, University Hassan II Casablanca, 53306, Casablanca, Morocco
| | - Mohamed Ouazzani Touhami
- Laboratory of Mechanics, Faculty of Sciences Aïn Chock, University Hassan II Casablanca, 53306, Casablanca, Morocco
| | - Moussa Gomina
- CRISMAT UMR6508 CNRS, ENSICAEN, 6 boulevard Maréchal Juin, CEDEX 4, 14050, Caen, France
| | - Azzeddine Samdi
- Laboratory of Interface Materials and Environment, Faculty of Sciences Aïn Chock, University Hassan II Casablanca, 53306, Casablanca, Morocco
| | - Redouane Moussa
- Laboratory of Interface Materials and Environment, Faculty of Sciences Aïn Chock, University Hassan II Casablanca, 53306, Casablanca, Morocco
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Todaro F, Colangelo F, De Gisi S, Farina I, Ferone C, Labianca C, Petrella A, Cioffi R, Notarnicola M. Recycling of Contaminated Marine Sediment and Industrial By-Products through Combined Stabilization/Solidification and Granulation Treatment. MATERIALS (BASEL, SWITZERLAND) 2023; 16:ma16062399. [PMID: 36984279 PMCID: PMC10054810 DOI: 10.3390/ma16062399] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 02/26/2023] [Accepted: 03/14/2023] [Indexed: 06/01/2023]
Abstract
Stabilization/solidification (S/S) is becoming increasingly important, as it allows the remediation of contaminated sediments and their recovery into materials for civil engineering. This research proposes a cement-free cold granulation process for manufactured low-cost aggregates from marine sediments contaminated with organic compounds and metals. After the chemo-physical characterization of the study materials, two mix designs were prepared in a rotary plate granulator by adding two industrial by-products as geopolymer precursors, coal fly ash (CFA) and Blast Furnace Slag (BFS), but also alkaline activation solutions, water, and a fluidizer. The results indicated that sediments treated with mix 1 (i.e., with a higher percentage of water and fluidifier) represent the optimal solution in terms of metal leachability. The metal leachability was strictly influenced by aggregates' porosity, density, and microstructure. The technical performance (such as the aggregate impact value > 30%) suggested the use of granules as lightweight aggregates for pavement construction. The results indicated that cold granulation represents a sustainable solution to recycling contaminated marine sediments, CFA, and BFS into lightweight artificial aggregates.
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Affiliation(s)
- Francesco Todaro
- Department of Civil, Environmental, Land, Building Engineering and Chemistry (DICATECh), Polytechnic University of Bari, Via E. Orabona n. 4, 70125 Bari, Italy
| | - Francesco Colangelo
- Department of Engineering and INSTM Research Unit, University of Naples “Parthenope”, Centro Direzionale, Isola C4, 80143 Naples, Italy
| | - Sabino De Gisi
- Department of Civil, Environmental, Land, Building Engineering and Chemistry (DICATECh), Polytechnic University of Bari, Via E. Orabona n. 4, 70125 Bari, Italy
| | - Ilenia Farina
- Department of Engineering and INSTM Research Unit, University of Naples “Parthenope”, Centro Direzionale, Isola C4, 80143 Naples, Italy
| | - Claudio Ferone
- Department of Engineering and INSTM Research Unit, University of Naples “Parthenope”, Centro Direzionale, Isola C4, 80143 Naples, Italy
| | - Claudia Labianca
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Andrea Petrella
- Department of Civil, Environmental, Land, Building Engineering and Chemistry (DICATECh), Polytechnic University of Bari, Via E. Orabona n. 4, 70125 Bari, Italy
| | - Raffaele Cioffi
- Department of Engineering and INSTM Research Unit, University of Naples “Parthenope”, Centro Direzionale, Isola C4, 80143 Naples, Italy
| | - Michele Notarnicola
- Department of Civil, Environmental, Land, Building Engineering and Chemistry (DICATECh), Polytechnic University of Bari, Via E. Orabona n. 4, 70125 Bari, Italy
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Influence of the Integration of Geopolymer Wastes on the Characteristics of Binding Matrices Subjected to the Action of Temperature and Acid Environments. Polymers (Basel) 2022; 14:polym14050917. [PMID: 35267740 PMCID: PMC8912663 DOI: 10.3390/polym14050917] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 02/15/2022] [Accepted: 02/20/2022] [Indexed: 01/27/2023] Open
Abstract
Recycling geopolymer waste, by reusing it as a raw material for manufacturing new geopolymer binding matrices, is an interesting asset that can add to the many technical, technological and environmental advantages of this family of materials in the construction field. This can promote them as promising alternatives to traditional materials, such as Portland cements, which are not so environmentally friendly. Recent studies have shown that the partial replacement of reactive aluminosilicates (metakaolin and fly ash) up to a mass rate of 50% by geopolymer waste does not significantly affect the compressive strength of the new product. In line with these findings, this paper investigates the effects of aggressive environments, i.e., high temperatures (up to 1000 °C) and acid attacks (pH = 2), on the characteristics of these new matrices. Different techniques were used to understand these evolutions: mineralogical analysis by X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TGA-DTA), mechanical characterization and scanning electron Microscopy (SEM) observations. The results are very satisfactory: in the exposure temperature range explored, the new matrices containing geopolymer waste suffered losses in compressive strength similar to those of the matrices without waste (considered as materials reference). On the other hand, the new matrices exhibited good chemical stability in acid media. These results confirm that the reuse of geopolymer waste is a promising recycling solution in the construction sector.
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