Microstructure-based prediction of thermal properties of cement paste at early ages

The time-dependent process of cement hydration affects many physical and mechanical properties of the cement-based materials, particularly at early ages. To estimate the thermomechanical response of cementitious composites, such as concrete, determination of thermal properties, including heat capacity, thermal conductivity and coefficient of thermal expansion, are necessary. An effort is made in the present study to predict the thermal behaviour of cement pastes by simulating the development of the microstructure during the hydration progress. The model deals with the thermal properties of main cement hydration products, Calcium-Silicate-Hydrate (C-S-H) and Calcium Hydroxide CH, and the change in their volume fraction in the microstructure. The paper discusses the results of thermal conductivity and the specific heat capacity from the model, and they are compared to some recent experimental data from the literature.This work was financially supported by: Project POCI-01-0145-FEDER-007457 (CONSTRUCT - Institute of R&D in Structures and Construction) and by project POCI-01- 0145-FEDER-007633 (ISISE), funded by FEDER funds through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI), and by national funds through FCT - Fundação para a Ciência e a Tecnologia. FCT and FEDER (COMPETE2020) are also acknowledged for the funding of the research project IntegraCrete PTDC/ECMEST/1056/2014 (POCI-01-0145-FEDER-016841). The financial support of COST Action TU1404 through its several networking instruments is also gratefully acknowledged.