Circular insulation material: characterisation and bio-solubility of waste mineral wool for blown-in insulation applications

Mineral wool is extensively utilized worldwide for thermal and acoustic insulation in buildings. However, the widespread use of these materials has led to a significant increase in construction and demolition (C&D) waste, much of which is either landfilled or incinerated. With the increasing emphasis on sustainability and circular economy practices, the low-energy recycling of mineral wool waste as blown-in insulation emerged as a promising pathway to reduce landfill burdens, conserve resources, and close material loops with minimal processing. This study aims to investigate the chemical and physical properties of the shredded waste mineral wool as well as its health and safety aspects in order to be reused as a blown-in insulation. To benchmark performance and safety of short fibers, a comparative analysis was also conducted against virgin mineral wool samples. The waste mineral wool insulation boards were shredded into loose form, which were then characterized using chemical methods such as FTIR and XRF. The physical properties such as bulk density, thermal conductivity, water absorption, vapour sorption and water contact angle were also analyzed. In addition, an in-vitro dissolution test was conducted to assess the bio-solubility of short inorganic fibres. Despite having a lower silicon content, XRF revealed that the chemical compositions of waste mineral wool were similar to virgin counterparts. Although the thermal conductivity of waste mineral wool increases, the λ-value remained within the permissible range, indicating its potential use in blown-in insulation. The in-vitro bio-solubility of short fibres through a batch dissolution method showed that all the samples except waste stone wool reached the threshold level after 14 days. • Waste and virgin wool are chemically similar • Waste wool absorbs water faster due to degraded hydrophobic coating • Thermal conductivity of waste mineral wool is slightly higher than their virgin counterparts • All wool samples passed bio-solubility tests except waste stone wool • Waste mineral wool is a viable insulation material