Advances in understanding cement hydration mechanisms

• Published in: Cement and concrete research Vol. 124; p. 105823
• Main Authors: Scrivener, Karen, Ouzia, Alexandre, Juilland, Patrick, Kunhi Mohamed, Aslam
• Format: Journal Article
• Language: English
• Published: Elmsford Elsevier Ltd 01-10-2019; Elsevier BV
• Subjects: Acceleration; Aluminum oxide; Cement; Cement hydration; Consumption; Deceleration; Diffusion rate; Hydration; Induction period; Later ages; Main hydration peak; Morphology; Portland cements; Tricalcium silicate; Induction period; Main hydration peak; Later ages; Hydration; Cement
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/j.cemconres.2019.105823

Progress in understanding hydration mechanisms of alite and Portland cement is reviewed. Up to the end of the induction period, dissolution rates determined by the undersaturation of the solution dominate the reaction, but, better understanding is needed about the alite solution interface. The main heat evolution peak hydration is dominated by the growth of outer C-S-H with a spiky or “needle” like morphology. Growth is rapid over several hours (acceleration period) and then slows (deceleration period). At later ages the consumption of water and lack of water filled pores above about 10 nm, along with the consumption of anhydrous material are major factors leading to the continual reduction in the rate of reaction. There is no evidence that diffusion becomes the rate controlling mechanism even at this stage. The microstructure of cement differs significantly from that of alite, largely due to the influence of alumina on C-S-H growth and distribution.