Experimental Investigation and Characterization of the Thermal Insulating Behavior of Municipal Solid Waste and its Constituents

Rapid urbanization and industrialization have resulted in the massive expansion of municipal solid waste (MSW) generation. Although there are various waste management methods in place to handle MSW, exploring new opportunities for utilizing MSW is also welcoming in today’s world to reduce landfill volumes, conserve resources, and potentially avoid/reduce emissions. This study focused on utilization of MSW as a thermal insulation with a goal to benchmark the performance with a commercial insulation. The MSW and various fractions of MSW (e.g., paper, plastic) were mechanically processed through high-torque twin-shaft shredder and knife mills to make different sized materials (e.g., 13, 6, 4, and 2 mm). The physical properties of the materials were investigated in terms of density, porosity, compressibility while the thermal properties were examined in terms of thermal conductivity, diffusivity, and R-value (thermal resistance). In addition, the fire retardancy of the studied materials were explored in terms of ignition time, heat release rate, effective optical obscuring area, etc. The results showed that processed MSW can easily reach performance of commercial cellulose product within 70%. Whole 6 mm shredded MSW had a R-value comparable to that of the commercial cellulose product (2.6 (0.45) compared to 3.2 (0.56) °F⋅ft2⋅h/BTU (m2K/W)). Smaller particle sizes led to less flame-retardant behavior as well as increased density. Higher bulk porosity led to higher thermal resistivity and improved R-value. Thermal insulation properties of MSW are investigated. R-value is highly dependent on packing density and mean particle size. Composition of the MSW does not significantly impact its thermal properties. R-values of tested MSW are within 70% of the commercial cellulose insulation.