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

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites Pub Date : 2024-11-26 DOI:10.1016/j.cemconcomp.2024.105870

Xiaodi Dai , Sharu Bhagavathi Kandy , Narayanan Neithalath , Aditya Kumar , Mathieu Bauchy , Edward Garboczi , Torben Gaedt , Samanvaya Srivastava , Gaurav Sant

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引用次数: 0

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.

查看原文本刊更多论文

通过添加 Ca(OH)2 进行热刺激硬化和粉煤灰碱性活化可促进 3D 打印技术的发展

三维打印技术可为建筑行业带来巨大的好处，包括制造定制部件、消除模板和减少材料浪费。尽管有这些优势，但控制三维打印混凝土（3DPC）的可泵性、可挤出性和可施工性仍具有挑战性。本研究展示了粉煤灰（FA）如何在存在波长石（Ca(OH)2，CH）的情况下增强热刚度和快速碱活化。一般来说，CH 和 FA 的混合物在低温下的结构形成较少，但当达到 75 °C 的触发温度时，这些混合物会以 ∼800 Pa/s 的速度快速硬化。快速硬化的原因是 CH 颗粒的絮凝，以及 CH 和 FA 之间开始发生热固性/碱激活反应，从而在硬化过程中形成 C-A-S-H 和 N-A-S-H。对 FA-CH 混合比的精心选择（CH 质量百分比在 20 ∼ 20% 时为最佳）可为 3D 打印应用提供无水泥配方。这些成果对建筑用碳效率配方的替代原料途径具有重要意义。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Cement & concrete composites 工程技术-材料科学：复合

CiteScore

18.70

自引率

11.40%

发文量

459

审稿时长

65 days

期刊介绍： Cement & concrete composites focuses on advancements in cement-concrete composite technology and the production, use, and performance of cement-based construction materials. It covers a wide range of materials, including fiber-reinforced composites, polymer composites, ferrocement, and those incorporating special aggregates or waste materials. Major themes include microstructure, material properties, testing, durability, mechanics, modeling, design, fabrication, and practical applications. The journal welcomes papers on structural behavior, field studies, repair and maintenance, serviceability, and sustainability. It aims to enhance understanding, provide a platform for unconventional materials, promote low-cost energy-saving materials, and bridge the gap between materials science, engineering, and construction. Special issues on emerging topics are also published to encourage collaboration between materials scientists, engineers, designers, and fabricators.