Fabrication and performance of foamed alkali-activated materials by in-situ gas generation from metallic silicon powder

TY - JOUR

T1 - Fabrication and performance of foamed alkali-activated materials by in-situ gas generation from metallic silicon powder

AU - Li, Fangxian

AU - Wang, Zijing

AU - Lu, Chunyu

AU - Zheng, Li

AU - Wei, Jiangxiong

N1 - Publisher Copyright: © 2025 Elsevier Ltd

PY - 2025/10/17

Y1 - 2025/10/17

N2 - This study presents an innovative, autoclave-free approach to fabricate foamed alkali-activated materials (FAAMs) using metallic silicon (Si) powder as a novel in-situ foaming agent, overcoming the process control challenges associated with the rapid reaction of conventional agents like aluminum powder. The unique four-stage gas evolution kinetics of Si powder, with a crucial induction period of 15–30 min, enables effective synchronization between gas evolution and alkali-activated materials (AAMs) setting. By optimizing key parameters such as water-to-solid (W/S) ratio, water glass modulus (WGM), and Si content, the process prevents pore coalescence and achieves a uniform microstructure of discrete, near-spherical mesopores (100–300 µm) with robust, integral walls. Notably, the resulting Si-foamed alkali-activated materials (density ≈500 kg/m³) demonstrate an excellent balance of properties, achieving a low oven-dry thermal conductivity of 0.117 W·m⁻¹ ·K⁻¹ and a high compressive strength of up to 3.01 MPa under steam-curing. These findings establish Si-foaming as a promising, low-carbon method for producing lightweight and sustainable insulation for the construction industry.

AB - This study presents an innovative, autoclave-free approach to fabricate foamed alkali-activated materials (FAAMs) using metallic silicon (Si) powder as a novel in-situ foaming agent, overcoming the process control challenges associated with the rapid reaction of conventional agents like aluminum powder. The unique four-stage gas evolution kinetics of Si powder, with a crucial induction period of 15–30 min, enables effective synchronization between gas evolution and alkali-activated materials (AAMs) setting. By optimizing key parameters such as water-to-solid (W/S) ratio, water glass modulus (WGM), and Si content, the process prevents pore coalescence and achieves a uniform microstructure of discrete, near-spherical mesopores (100–300 µm) with robust, integral walls. Notably, the resulting Si-foamed alkali-activated materials (density ≈500 kg/m³) demonstrate an excellent balance of properties, achieving a low oven-dry thermal conductivity of 0.117 W·m⁻¹ ·K⁻¹ and a high compressive strength of up to 3.01 MPa under steam-curing. These findings establish Si-foaming as a promising, low-carbon method for producing lightweight and sustainable insulation for the construction industry.

KW - Foamed Alkali-Activated Materials

KW - In-situ gas generation

KW - Metallic silicon

KW - Pore structure

KW - Thermal insulation

UR - https://www.scopus.com/pages/publications/105016307880

U2 - 10.1016/j.conbuildmat.2025.143688

DO - 10.1016/j.conbuildmat.2025.143688

M3 - Article

AN - SCOPUS:105016307880

SN - 0950-0618

VL - 495

JO - Construction and Building Materials

JF - Construction and Building Materials

M1 - 143688

ER -