Investigating the Effects of H2O Interaction with Rainscreen Façade ACMs During Fire Exposure

Preliminary investigations into adverse reactions between aluminum alloy sheets, used as facings for aluminum composite material rainscreen panels, and water vapor (2Al + 3H2O −> Al2O3 + 3H2) contributing to high-rise façade fire events are reported. Panels containing a PE blend (70% polyethylene 30% calcium carbonate) core were characterised and subsequently exposed to a surface irradiance of 50 kW/m2 using a cone calorimeter, in modified ISO 5660:1/ASTM 1354 procedures, involving water spray. Inverse modeling techniques were applied to determine the effects of water spray on the samples’ combustion parameters. From the current study, evidence for the liberation of diatomic hydrogen (H2) contributing to peak heat release rate during combustion was not found. Observed thermal shock and subsequent degradation led to a greater surface area exposure of combustible inner core material, contributing to an increase for both peak heat release rate (from 393 kW/m2 to 1040 kW/m2) and total energy release (97 MJ/m2 to 117 MJ/m2). Findings suggest no significant increase in the combustibility of aluminum composite panels arises through reduction–oxidation reactions between aluminum-water at 50 kW/m2 irradiance. However, thermomechanical processes, brought upon by environmental conditions and external intervention, may affect the dynamic combustion behavior of aluminum composite panels.