Thermo-mechanical stability of supplementary cementitious materials in cement paste to be incorporated in concrete as thermal energy storage material at high temperatures

• Published in: Journal of energy storage 2022-10, Vol.54, p.105370, Article 105370
• Main Authors: Boquera, Laura, Castro, J. Ramon, Pisello, Anna Laura, Fabiani, Claudia, D'Alessandro, Antonella, Ubertini, Filippo, Cabeza, Luisa F.
• Format: Article
• Language: English
• Subjects: Calcium aluminate cement; Cement paste; High temperature; Portland cement; Supplementary cementitious materials; Thermal energy storage
• ISSN: 2352-152X; 2352-1538
• DOI: 10.1016/j.est.2022.105370

The incorporation of recycled materials in concrete as a partial replacement of cement is becoming an alternative strategy for decreasing energy-intensive and CO2 emissions imputable to the cement manufacture, while investigating new potential uses of such multifunctional materials for environmental sustainability opportunities. Therefore, low-cost and worldwide availability of by-products materials is being assessed for sensible heat thermal energy storage applications based on cementitious materials. A greater concern is especially required focusing on the thermal stability of cement paste under high temperature cycled conditions. Moreover, compatibility between cement type and supplementary cementitious materials is determinant for the proper performance reliability. In this study, benchmark cement types were selected, i.e., ordinary Portland and calcium aluminate. Six supplementary cementitious materials were added to both types of cement in a content of 10 % and 25 %. Thermo-mechanical properties were studied before and after 10 thermal cycles from 290 to 650 °C. Results after thermal cycling showed that calcium aluminate cement paste mixtures maintained their integrity. However, most ordinary Portland cement paste mixtures were deteriorated: only mixtures with 25 % cement replacement with chamotte, flay ash, and ground granulated blast furnace slag remained without cracks. Calcium aluminate cement paste mixtures obtained the highest compressive strength, for partial replacement of cement with 10 % of chamotte, ground granulated blast furnace slag, and iron silicate. The incorporation of supplementary cementitious materials did not increase the thermal conductivity. •Two cement types were used, ordinary Portland (OPC) and calcium aluminate (CAC).•Six supplementary cementitious materials were added in a content of 10 % and 25 %.•Thermo-mechanical properties were studied after 10 thermal cycles from 290 to 650 °C.•Results after thermal cycling showed that CAC paste mixtures maintained their integrity.•Most OPC paste mixtures were deteriorated.