Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Hydraulic Pastes of Alkali-Activated Waste Glass and Limestone Cement Using in Situ Caustification
https://orcid.org/http://orcid.org/0000-0002-0696-6573
One-part waste glass (WG) and limestone (LS) alkali-activated cements were investigated in pastes using powdered activators CaO+Na2CO3. 9 formulations of pastes were selected from a full factorial experimental design with %LS, %Na2O-Na2CO3 and %CaO as factors. The activators promoted an in situ caustification that dissolved the WG amorphous structure leading to the formation of cementitious reaction products. The pastes developed 1-year strengths up to 35 MPa and were stable underwater. The characterization by SEM, EDS and 29Si-NMR indicated that while using a Na2CO3:CaO ratio close to 1:1, the main reaction products were polymerized C-S-H, silica gel and modified silica gel, intimately intermixed and crosslinked through Q3 bonds. Such coexistence of reaction products was better in terms of strength and underwater stability than those coexisting in pastes of WG+LS systems activated with solutions of only NaOH reported in literature. Moreover, curing underwater promoted the formation of shorter silicon-oxygen chains, suggesting more formation of C-S-H; nonetheless, the considerable presence of Q3 and Q4 signals along with a 1-year compressive strength of 32 MPa in pastes cured underwater evidenced that most of the silica gel was stable. The results indicated that in situ caustification is a promising one-part activation for SiO2-rich precursors such as waste glass to develop hydraulic alkali activated cements with low cost and CO2 emissions.
Hydraulic Pastes of Alkali-Activated Waste Glass and Limestone Cement Using in Situ Caustification
https://orcid.org/http://orcid.org/0000-0002-0696-6573
One-part waste glass (WG) and limestone (LS) alkali-activated cements were investigated in pastes using powdered activators CaO+Na2CO3. 9 formulations of pastes were selected from a full factorial experimental design with %LS, %Na2O-Na2CO3 and %CaO as factors. The activators promoted an in situ caustification that dissolved the WG amorphous structure leading to the formation of cementitious reaction products. The pastes developed 1-year strengths up to 35 MPa and were stable underwater. The characterization by SEM, EDS and 29Si-NMR indicated that while using a Na2CO3:CaO ratio close to 1:1, the main reaction products were polymerized C-S-H, silica gel and modified silica gel, intimately intermixed and crosslinked through Q3 bonds. Such coexistence of reaction products was better in terms of strength and underwater stability than those coexisting in pastes of WG+LS systems activated with solutions of only NaOH reported in literature. Moreover, curing underwater promoted the formation of shorter silicon-oxygen chains, suggesting more formation of C-S-H; nonetheless, the considerable presence of Q3 and Q4 signals along with a 1-year compressive strength of 32 MPa in pastes cured underwater evidenced that most of the silica gel was stable. The results indicated that in situ caustification is a promising one-part activation for SiO2-rich precursors such as waste glass to develop hydraulic alkali activated cements with low cost and CO2 emissions.
Hydraulic Pastes of Alkali-Activated Waste Glass and Limestone Cement Using in Situ Caustification
https://orcid.org/http://orcid.org/0000-0002-0696-6573
One-part waste glass (WG) and limestone (LS) alkali-activated cements were investigated in pastes using powdered activators CaO+Na2CO3. 9 formulations of pastes were selected from a full factorial experimental design with %LS, %Na2O-Na2CO3 and %CaO as factors. The activators promoted an in situ caustification that dissolved the WG amorphous structure leading to the formation of cementitious reaction products. The pastes developed 1-year strengths up to 35 MPa and were stable underwater. The characterization by SEM, EDS and 29Si-NMR indicated that while using a Na2CO3:CaO ratio close to 1:1, the main reaction products were polymerized C-S-H, silica gel and modified silica gel, intimately intermixed and crosslinked through Q3 bonds. Such coexistence of reaction products was better in terms of strength and underwater stability than those coexisting in pastes of WG+LS systems activated with solutions of only NaOH reported in literature. Moreover, curing underwater promoted the formation of shorter silicon-oxygen chains, suggesting more formation of C-S-H; nonetheless, the considerable presence of Q3 and Q4 signals along with a 1-year compressive strength of 32 MPa in pastes cured underwater evidenced that most of the silica gel was stable. The results indicated that in situ caustification is a promising one-part activation for SiO2-rich precursors such as waste glass to develop hydraulic alkali activated cements with low cost and CO2 emissions.
Hydraulic Pastes of Alkali-Activated Waste Glass and Limestone Cement Using in Situ Caustification
RILEM Bookseries
Escalante-Garcia, J. Ivan (Herausgeber:in) / Castro Borges, Pedro (Herausgeber:in) / Duran-Herrera, Alejandro (Herausgeber:in) / Menchaca-Ballinas, L. E. (Autor:in) / Escalante-García, J. I. (Autor:in)
RILEM Annual Week ; 2021 ; Merida, Mexico
Proceedings of the 75th RILEM Annual Week 2021 ; Kapitel: 71 ; 656-666
RILEM Bookseries ; 40
11.03.2023
11 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
Shrinkage Behavior of Alkali-Activated Slag Cement Pastes
| Trans Tech Publications | 2018
Thaumasite formation in Portland-limestone cement pastes
| Tema Archiv | 1999
Thaumasite formation in Portland-limestone cement pastes
| British Library Conference Proceedings | 1999
Alkali binding in cement pastes
| Online Contents | 1999
PAPERS - Thaumasite formation in Portland-limestone cement pastes
| Online Contents | 1999