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Thermally stimulated stiffening and fly ash's alkaline activation by Ca(OH)2 addition facilitates 3D-printing.

Authors :
Dai, Xiaodi
Kandy, Sharu Bhagavathi
Neithalath, Narayanan
Kumar, Aditya
Bauchy, Mathieu
Garboczi, Edward
Gaedt, Torben
Srivastava, Samanvaya
Sant, Gaurav
Source :
Cement & Concrete Composites. Feb2025, Vol. 156, pN.PAG-N.PAG. 1p.
Publication Year :
2025

Abstract

3D-printing could offer substantial benefits to the construction industry including the fabrication of customized/bespoke components, eliminating formwork, and reducing material waste. Despite these advantages, control of the pumpability, extrudability, and buildability of 3D-printed concrete (3DPC) remains challenging. This study demonstrates how the use of fly ash (FA) enables enhanced thermal stiffening, and rapid alkali-activation in the presence of portlandite (Ca(OH) 2 , CH). In general, blends of CH and FA exhibit less structural build-up at low temperatures, but upon reaching a trigger temperature of 75 °C, these blends achieve rapid stiffening, at rates of ∼800 Pa/s. The rapid stiffening arises from the flocculation of CH particles, and the onset of the pozzolanic/alkali-activation reactions between CH and FA, resulting in the formation of C-A-S-H and N-A-S-H during stiffening. Careful selection of the FA-CH blend ratio, which displays an optimum at ∼20 mass % CH, enables the composition of cement-free formulations for 3D-printing applications. The outcomes have important implications on alternate feedstock pathways to compose carbon-efficient formulations for construction. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
09589465
Volume :
156
Database :
Academic Search Index
Journal :
Cement & Concrete Composites
Publication Type :
Academic Journal
Accession number :
181490634
Full Text :
https://doi.org/10.1016/j.cemconcomp.2024.105870