PRELIMINARY THERMO-MECHANICAL CHARACTERIZATION OF CEMENT-BASED MATERIALS FOR LLW IMMOBILIZATION

The aim of the study is to investigate the thermo- mechanical properties of cement-based materials for immobilization of low/intermediate level waste. The cementation is an important technology, nevertheless the durability of such waste form must be studied in consideration of the institutional period of storage or even under disposal conditions. Moreover, if liquid organic wastes are immobilized into cement matrix, we must face a significant technological challenge due to their complex chemical composition and relatively high activity. To investigate the durability of cement cement-based materials, an experimental campaign was carried out by performing hot wire tests on (aged/unaged) cylindrical concrete samples at temperatures ranging from 100 to 800 degrees C. The determination of thermal conductivity up to 800 degrees C was obtained according to the Hot Wire Parallel Method. Additional characterization procedures included X-ray inspection, porosity measurements, compressive strength testing, and aging investigations. The activity was developed within the framework of the H2020 PREDIS project. Further, numerical simulation by finite element method (FEM) was carried out to properly consider different conditions. The obtained results show that the cement matrix demonstrated a good level of thermal, and physical stability. The visual and Xray inspections of the samples did not reveal any significant damages that would affect the thermal performance of the studied cement-based material. The thermal conductivity results obtained were found to be consistent with literature values, indicating a strong correlation between the simulation results and established knowledge in the field.