"Evaluation of Fresh Properties of High Calcium Content Fly Ash-based A" by Fareh Abudawaba, Eslam Gomaa et al.
 

Evaluation of Fresh Properties of High Calcium Content Fly Ash-based Alkali-activated 3D-Printed Mortar

Abstract

This study investigated the applicability of using class C fly ash (FA) having high calcium content to produce alkali-activated mortar (AAM) for 3D-printed concrete (3DPC). The fresh properties were examined through different tests including open time (OT), initial setting time (IST), immediate axial strain, and penetration test (PT), as well as the rheological characterization. In addition, the relationship between the OT, static yield stress (τo), and cycle time (CT) was discussed. Effect of water to FA (W/FA), alkaline activators to FA (Alk/FA), and sodium silicate to sodium hydroxide (SS/SH) ratios were studied to offer a wide selection of AAMs for different 3D-printing applications. The findings indicated that the OT for the mortar ranged from 4 to 93 min, suggesting suitable extrudability for 3D-printing. Variations were observed in OT, IST, and immediate axial strain based on the W/FA, Alk/FA, and SS/SH ratios. The τo evolution of AAMs linearly increased with rest time (trest) with R2 ranging from 0.91 to 0.99. The static yield stress evolution rate (Athix) ranged from 0.07 to 3.58 kPa/min. Regardless of the trest, the τo values obtained from the rheometer were about 17–53 % lower than the τo values obtained from the PT. The lowest estimated CT possible while avoiding a collapse of the 3DPC structure was based on the Athix and shear stress induced from gravity. The study demonstrated that by adjusting the AAM composition, properties can be tailored to suit specific 3D-printing requirements, highlighting the material's adaptability for diverse applications.

Department(s)

Civil, Architectural and Environmental Engineering

Keywords and Phrases

3D-printing; Alkali-activated mortar; Ambient curing; Class C fly ash; Cycle time; Open time; Static yield stress evolution

International Standard Serial Number (ISSN)

2352-7102

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2025 Elsevier, All rights reserved.

Publication Date

15 Jun 2025

Share

 
COinS
 
 
 
BESbswy