General Evaluation of the Recyclability of Polyester-Glass Laminates Used to Reinforce Steel Tanks

Polyester-glass laminates are widely used to reinforce underground steel fuel tanks due to their excellent corrosion resistance and mechanical performance. However, the management of these composites at the end of their service life poses significant challenges, particularly in terms of material recovery and environmental impact. This study investigates both the structural benefits and recyclability of polyester-glass laminates. Numerical simulations confirmed that reinforcing corroded steel tank shells with a 5 mm GFRP (Glass Fiber Reinforced Polymer) coating reduced the maximum equivalent stress by nearly 50%, significantly improving mechanical integrity. In parallel, thermogravimetric and microscopic analyses were conducted on waste GFRP samples subjected to pyrolysis, gasification, and combustion. Among the methods tested, pyrolysis proved to be the most favorable, allowing substantial organic degradation while preserving the structural integrity of the glass fiber fraction. However, microscopy revealed that the fibers were embedded in a dense char matrix, requiring additional separation processes. Although combustion leaves the fibers physically loose, pyrolysis is favored due to better preservation of fiber mechanical properties. Combustion resulted in loose and morphologically intact fibers but exposed them to high temperatures, which, according to the literature, may reduce their mechanical strength. Gasification showed intermediate performance in terms of energy recovery and fiber preservation. The findings suggest that pyrolysis offers the best trade-off between environmental performance and fiber recovery potential, provided that appropriate post-treatment is applied. This work supports the use of pyrolysis as a technically and environmentally viable strategy for recycling polyester-glass laminates and encourages further development of closed-loop composite waste management.