Incorporation of silica in C-S-H phases in alkaline conditions

SCK•CEN Mentor

Ferrand Karine, kferrand@sckcen.be, +32 (0)14 33 31 28

Expert group

R&D Waste Packages

SCK•CEN Co-mentor

Lemmens Karel, klemmens@sckcen.be, +32 (0)14 33 31 38

Introduction

An important mechanism affecting the dissolution behavior of nuclear alumino-boro-silicate waste glass in contact with concrete based on ordinary portland cement, is the reaction of silica from the glass with Ca (portlandite) from the concrete (pozzolanic reaction), leading to the formation of C-S-H phases. The further incorporation of glass silica in these C-S-H phases to reach higher Si/Ca ratios may be another driving force for glass dissolution. Previous studies were done with glass in contact with concrete, where both mechanisms occur simultaneously, and where the supply with silica depends on the glass dissolution rate. To isolate the silica incorporation in the C-S-H from the other mechanisms, a simplified system will be tested, using only predissolved silica and pre-characterized C-S-H phases.

 

Objective

The study would consist of laboratory experiments with interpretation supported by geochemical modeling.

The laboratory experiments would be mainly batch sorption tests with Si rich alkaline solutions and well characterized C-S-H phases.

The experiments should make clear the silica incorporation capacity and silica incorporation kinetics of the tested C-S-H phases.

 

 

The minimum diploma level of the candidate needs to be

A2: Upper secondary school (+7th year BSO)

The candidate needs to have a background in

Bio-engineering