Use of calorimetry and thermal analysis to assess the heat of supplementary cementitious materials during the hydration of composite cementitious binders

摘要

The present paper focuses on the suitability, variability and versatility of thermal analysis and calorimetry methods in the study of cement hydration as physical and chemical process including pozzolanicity and hydraulicity of supplementary cementitious materials. Isothermal calorimeter TAM AIR and simultaneous TGA/DSC were used. Not only activation energy of system comprising SCMs, but also heat generated through alkali-activated reaction of metakaolin and ground granulated blast furnace slag (BFS) can be successfully determined by using conduction calorimetry. The incremental heat flow and incremental cumulative heat of the alkali-activated reaction of ground granulated BFS and metakaolin (MK) were determined and found dependent on temperature and mass ratio between cement and SCMs. The incremental heat flow presents the same characteristics as parent heat flow with different peaks, denoting the formation of C-S-H, ettringite and C-A-S-H trough alkali-activated reaction. While BFS and MK influenced moderately the formation of C-S-H, their influence on the formation of C-A-S over bar -H (ettringite and monosulphate) and C-A-S-H is significant as evidenced by peak position and intensity. The method of calorimetry coupled with thermal analysis was considered sufficient to assess the pozzolanicity and hydraulicity of SCMs.