The valorization of industrial waste is crucial for sustainability in the construction sector. This study assesses the pozzolanic reactivity of waste materials from the Portuguese glass industry specifically soda-lime flat glass cutting waste (R2) and polishing sludge (R3), using the modified Chapelle method. Samples were collected directly from disposal areas without prior sorting by type and were not subjected to washing processes, thus closely reflecting real industrial waste generation and disposal conditions. The results revealed that both types of waste exhibit pozzolanic activity, with the polishing sludge (R3) demonstrating high reactivity comparable to that of silica fume. These findings suggest significant potential for these materials in the production of sustainable mortars and concretes, particularly for use in the rehabilitation of traditional buildings. Further studies are required to validate the long-term performance and durability of these materials.