Characterization of the microstructure of cement paste exposed to gamma radiation by scanning electron microscopy

Abstract

Hardened cement paste with a water-cement ratio of 0.4 was examined under five different relative humidity (RH) conditions (11 %, 33 %, 76 %, 96 %, and 100 %). These samples were exposed to gamma radiation with a total dose of 13.82 MGy over 341 days. Scanning electron microscopy (SEM) was the primary tool used for characterizing the samples’ microstructure at a microscale, aided by image analysis (IA), which showed negligible changes in Calcium-Silicate-Hydrate phases but a decrease in Portlandite of 1.5–3.5 % under 33–100 % RH conditions. Point elemental analysis was conducted to determine the (Ca-S)/Si ratio of the inner product, finding a significant increase of up to 20 % at medium RH conditions (33–76 %).