3D printable earth-based alkali activated �ink�: Effect of alkali concentration and binder-to-aggregate ratio

Sahoo, P and Gupta, S (2024) 3D printable earth-based alkali activated �ink�: Effect of alkali concentration and binder-to-aggregate ratio. In: Journal of Building Engineering, 98 .

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Abstract

This research attempts to investigate the effect of activator concentration (4 mol/L (M) and 8M) and binder-to-aggregate (B:A) ratio (ranging from 1:1 to 1:3 by weight) on extrudability and buildability of 3D printable natural earth-based alkali-activated materials (EAAM). It is found that natural clay in soil, used to replace 25 of M-sand, imparts higher thixotropy, evident from 90 to 100 recovery in viscosity compared to 65�80 for corresponding control (containing only M-sand and no soil). Presence of clay increases the dynamic yield stress than control but reduces the plastic viscosity by 80 � 90 in EAAM compared to corresponding control where interlocking between sand particles resists smooth extrusion of the material. EAAMs made with 8M NaOH have higher flow retention and maintain 95�100 recovery in viscosity for longer duration than 4M EAAM. This contributes to superior extrusion quality of 8M EAAM than 4M EAAM. The findings suggest that binder content can be reduced as concentration of NaOH is increased from 4M to 8M. This is evident from lower layer deformation (0.09 of original height) under self-weight and higher 3D printed buildable height of at least 457 mm in 8M EAAM with B:A of 1:2 compared to a maximum of 375 mm for 4M EAAM at higher B:A of 1:1. Ratios of wet compressive strength to dry compressive strength vary between 0.92 and 1.09 in 8M EAAM compared to 0.79 � 0.85 for 4M EAAM at 28-day age, suggesting lower sensitivity to moisture due to improved clay stabilization. Based on the strength and moisture sensitivity, the developed material can serve as a low-carbon and durable alternative to Portland cement in the construction of masonry elements in buildings, including cavity walls, panels, flooring tiles and façade members. © 2024 Elsevier Ltd

Item Type:	Journal Article
Publication:	Journal of Building Engineering
Publisher:	Elsevier Ltd
Additional Information:	The copyright for this article belongs to publisher.
Keywords:	Binders; Compressive strength; Extrusion; Portland cement; Tropics; Walls (structural partitions); Yield stress, 3-D printing; 3D-printing; Activated materials; Aggregate ratios; Alkali concentrations; Alkali-activated; Alkali-activated binder; Natural soils; Strength; Thixotropy, Aggregates
Department/Centre:	Division of Mechanical Sciences > Centre for Sustainable Technologies (formerly ASTRA)
Date Deposited:	26 Nov 2024 12:56
Last Modified:	26 Nov 2024 12:56
URI:	http://eprints.iisc.ac.in/id/eprint/86938

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