Investigation of Fire Performance of Recycled Carbon Fiber-reinforced Alkali-activated Cement Composites

Description

The integrity of building materials under fire is an essential consideration in civil engineering. The physical, mechanical, and durability properties of cementitious composites suffer from fire degradation. Concrete is one such material that loses strength when exposed to fire, resulting in structural failures, casualties, and economic losses. A building fire on November 15, 2010 in Shanghai (China) caused 129 casualties and a direct economic loss of 158 million RMB due to the collapse of the concrete structure. The cement industry is facing the demanding challenge of reducing its carbon footprint. Alkali-activated cement (AAC) is a sustainable solution to minimizing the industry’s carbon emission by up to 80% at a low cost. However, a broader application of AAC is constrained by the lack of aluminosilicate-rich precursor materials. A potential solution to this issue is to recycle waste glass (WG) from decommissioned solar panels and use it as an AAC precursor material. However, WG-derived AAC composites can lose more strength at high temperatures than conventional Portland cement composites. Sustainable recycled carbon fibers (rCFs) from end-of-life wind turbine blades may enhance the fire performance of WG-derived AAC. However, as rCF-reinforced AAC (rCFAC) composites are likely to exhibit complicated structural changes and coupled mechanisms at elevated temperatures, well-designed experiments and accurate numerical frameworks are needed to elucidate their structural responses under fire. During a fire, cementitious composites exhibit complex multiphysics phenomena involving the coupling of heat transfer, moisture transport, and mechanical deformation processes. The challenge lies in the accurate characterization of the strong nonlinear constitutive relationships resulting from material degradations and the strong discontinuities due to multiple cracking and even spalling. The proposed project will develop a fully coupled thermo-hygro-mechanical (THM) model by conducting rigorous experiments. This model will be used to study the THM mechanisms and behaviors of rCFAC composites at elevated temperatures. A multiscale multiphysics meshfree computational framework will be developed and validated using experimental results to predict the structural responses and failures of rCFAC composites under fire.  In the proposed project, a series of computational and experimental investigations will be conducted to evaluate the fire performance of newly developed rCFAC composites with different combinations of design variables. A multi-objective optimization of the composites will be further carried out to improve comprehensive design of rCFAC composites regarding fire safety, economic cost, and sustainability.