Refractory Bricks Characterization Manufactured from Geopolymers Based on Volcanic Ash

Almirón J.; Churata R.; Huanca-Zuñiga P.; Torres-Almirón J.; Acevedo-Obando G.; Tupayachy-Quispe D. · Key Engineering Materials (2026) · DOI: 10.4028/p-9vemam

Resumen

The aim of this study is to analyze the mechanical and physical properties of refractory bricks produced via geopolymerization using volcanic ash. Volcanic ash was combined with 12 M sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) as activators, with a liquid-to-solid ratio of 0.2. Two brick prototypes were produced: a cylindrical specimen for testing compressive strength and water absorption, and a rectangular prism for analyzing thermal conductivity. The bricks were calcined at 600°C and 800°C, showing favorable performance compared to well-known commercial refractory bricks. Cylindrical specimens calcined at 600°C reached an average compressive strength of 5.51 MPa, while those calcined at 800°C averaged 6.60 MPa—more than double the 2.80 MPa of commercial bricks. The average density of the specimens at both temperatures was similar, around 1.58 g/cm³, significantly higher than the 0.95 g/cm³ of commercial counterparts. Moreover, the average thermal conductivity of the geopolymer bricks was 0.008 W/m·K, indicating superior insulating properties compared to the 0.39 W/m·K of commercial refractory bricks. These results demonstrate optimal properties in refractory bricks made from geopolymer-based volcanic ash.

Instituciones: Universidad Nacional de San Agustín de Arequipa; Universidad Tecnológica del Perú; Universidad Católica de Santa María