Properties of fly ash-based spray-applied fire resistive materials

Abstract

Spray-applied fire-resistive materials (SFRMs) are one of the most commonly used passive fire protection materials due to their low thermal conductivity, lightweight, cost-effectiveness, and ease of application. Gypsum and Portland cement are commonly used in SFRMs to bind lightweight fillers and fibres. Due to the wide application of SFRMs, their production consumes large amounts of natural and non-renewable resources and contributes significantly to greenhouse gas emissions. This paper investigates the feasibility of using industrial by-products (e.g., fly ash) and waste materials (e.g., waste glass) to manufacture SFRMs with the aim of reducing the environmental impact. Accordingly, three SFRMs with different densities were developed utilising fly ash blended cement (FAC) and expanded glass. The use of FAC significantly reduced the use of Portland cement by 81% and achieved a 28-day compressive strength of 33.8–46.3 MPa for the binder. The developed SFRMs had average densities of 345 kg/m3, 560 kg/m3, and 698 kg/m3 for low-, medium-, and high-density groups, respectively. The compressive strengths of the SFRMs ranged from 747 kPa to 888 kPa, 6188 kPa to 7314 kPa, and 2343 kPa to 3535 kPa for the corresponding three groups, respectively. Additionally, the bond strengths of the corresponding SFRMs are 14.4 kPa–19.3 kPa (low-density), 34 kPa–40.9 kPa (medium-density), and 51.5 kPa–85.1 kPa (high-density), respectively. All the tested SFRMs met the requirements for density, compressive strength, bond strength, and non-combustibility. The thermal properties of the developed SFRMs were comparable to those of commercially available cementitious-based SFRMs in the same density group. In addition, using FAC instead of Portland cement could reduce carbon emissions by 68.4% and save costs by 38.4% in the Australian context.