Determining the Influence of Curing Temperature and SCMs on C-A-S-H Composition Using SEM-EDS Hypermaps

Abstract

Calcium-alumina-silicate-hydrate (C-A-S-H) is the main hydration product formed in Portland composite cement pastes. C-A-S-H is a key phase with regard to the strength and durability of concrete. Proper characterization of C-A-S-H is difficult due to intermixing with other phases, thus limiting the applicability of point scan analyses using scanning electron microscopy (SEM). Recent advances have enabled the use of hypermaps from energy dispersive spectroscopy (EDS) to investigate hydrate phases with better statistics. This study investigated how increased curing temperature and the inclusion of pozzolanic SCMs change the composition of the C-A-S-H, using the edxia plugin and SEM-EDS hypermaps. Composite cement pastes were cured at 20, 38, and 60°C for 180 days before analysis. We discuss the interpretation of the data from hypermaps in comparison to the traditional point scan approach.

Keywords

• sem-eds
• characterization
• c-s-h
• scm
• fly ash
• volcanic pozzolana