Microstructural analysis of cement paste: experimental and numerical investigation

Cement paste is a highly porous product of the chemical reactions of cement with water. The total process of cement hydration comprises a complex set of chemical and physical phenomena, discussed worldwide by many researchers. Many physical and mechanical properties of cement-based materials, such as concrete, depend on this hydration process, which alters the microstructure of cement paste and its pore network morphology throughout time. Therefore, for understanding and determining the mechanical and physical properties of a cement-based material, an adequate knowledge of its microstructure is essential. In the present work, a numerical modelling strategy is followed by using the computer code HYMOSTRUC3D for simulating the hydration process in cement paste, in which the microstructure of the latter is constructed on a cubic representative elementary volume (REV) as a function of time. Some model parameters are the water-to-cement ratio, the chemical composition of cement clinker and the temperature. In this paper, the degree of hydration and pore network morphology obtained from the numerical model are discussed and compared, respectively, with the results obtained from isothermal calorimetry and Mercury Intrusion Porosity (MIP) testing techniques.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 acknowledged for the funding of the research project PTDC/ECM-EST/1056/2014 (POCI-01-0145-FEDER-016841). The first author also thanks the individual grant with reference number of SFRH/BPD/114754/2016 funded by FCT.