# Mechanical and Sound Absorption Properties of Ice-Templated Porous Cement Co-Incorporated with Silica Fume and Fly Ash

## TL;DR

This paper introduces a new cement material made with industrial waste that is lighter, stronger, and better at absorbing sound.

## Contribution

A novel cement composite using fly ash and silica fume with enhanced mechanical and sound absorption properties via ice-templating.

## Key findings

- The composite shows 26.6% higher flexural strength and 30% greater toughness perpendicular to the lamellae.
- Noise reduction coefficient improves by 82% due to the material's unique microstructure.
- Compressive failure strain increases, indicating better deformability from the hybrid waste blend.

## Abstract

Reducing the consumption of energy-intensive cement and promoting the resource utilization of industrial waste are two critical challenges that should be urgently addressed to achieve the goals of carbon neutrality and green sustainable development in the building materials field. Among these, the massive stockpiling of industrial waste such as fly ash and silica fume poses serious threats to the environment and human health, making their efficient utilization an urgent need to alleviate environmental pressure. This study employs the ice-template method to incorporate fly ash and silica fume as functional components into a cement-based system, fabricating a novel composite material. This material features a layered porous structure, which not only reduces cement usage but also results in a lighter weight. The introduction of the ice-templating method successfully constructed an anisotropic lamellar structure, leading to significant enhancements in flexural strength and toughness—by approximately 26.6% and 30%, respectively, vertical to the lamellae compared to conventional dense cement. Meanwhile, the hybrid blend of silica fume and fly ash effectively improved the deformability of the material, as evidenced by a notable increase in compressive failure strain. These excellent behaviors of mechanical properties are attributed to the formation of a multi-scale microstructure characterized by “macroscopically continuous and microscopically dense” features. Moreover, this specific microstructure offers greater advantages in sound absorption performance. The acoustic impedance tube tests demonstrate that the noise reduction coefficient of the novel cement-based material incorporating fly ash and silica fume is improved by 82%, holding promising applications in noise reduction for the construction and transportation fields. This research provides a feasible pathway for the high-value application of industrial solid waste in low-carbon materials.