The effect of gamma radiation on the mechanical properties of inorganic polymers

Abstract

Currently, radioactive waste (RAW) is mainly conditioned using concrete and mortar based on Ordinary Portland. Unfortunately, these materials can present several drawbacks when exposed to the heat-emitting RAW and the accompanying radiation itself. Alkali-activated materials (AAM) are considered as interesting alternative candidates for application in nuclear safety structures since they are highly chemical and thermal resistant. If AAM are considered to be used for RAW management, their chemical and mechanical stability in a radiation field has to be proven.

In this study, the effect of gamma radiation on the mechanical and microstructural properties of AAM was investigated. For that purpose, 2 cm³ cubes of AAM were cast and irradiated using different dose rates (2 Gy/h, 7 Gy/h, and 2 kGy/h) until different absorbed doses with a maximum of 100 kGy. The effect of the gamma rays on the samples cured for 1d or 28d was evaluated. Another fourth dose rate (150 Gy/h) was used to evaluate the effect of the hardening time prior to irradiation. For each irradiation test, non-irradiated samples were kept as a reference at the same environmental conditions as the irradiated samples.

The effects were evaluated by means of compressive strength tests, SEM-imaging and porosity analysis (MIP and BET). The results were compared with similar studies on mortar and concrete samples.