The subject of the work is the characterization of lightweight aggregates intended for construction using the example of silica-clay raw material from south-eastern Poland (Dylągówka-Zapady deposit). The primary objective of the research is to assess the possibility of managing the accumulated organic waste, including cellulose pulp. This storage is problematic for processing plants and local government bodies and incurs high costs annually. Therefore, based on the patent (Kukułka et al. Method of producing raw meal, dried clay granules, and fired clay granules and the production line of raw meal, dried clay granules, and baked clay granules. Patent RP no P.429284.), an attempt was made to confirm the assumptions of the technology of fired clay granules, which can be used for zootechnical, agricultural, and construction purposes. The presented work assessed the physicochemical transformations in the clay-silica raw material after adding a significant amount of cellulose waste (10%, 20%, and 30%) in the temperature range of 25–1300 °C were assessed. Thermal methods such as thermodilatometry, Hot-Stage Microscopy with image analysis (IA-HSM) and thermal DSC/TG analysis with gas analysis were used for this purpose. Based on the first method, a temperature range was established in which sintering occurs without an apparent effect of densification. Therefore, the range of 850–950 °C was used to obtain fired granules, which were tested as a material for lightweight aggregates.