Expansive Reactions and Nanoindentation

Date This project started on 01 June 2008 and ended on 28 February 2010

Status This project is Finished

Authors
Czech Technical University in Prague, Czech Republic
OXAND S.A., France
University of Aberdeen, UK
Objectives
State of the Art : Although expansive phase formation in structural concrete can lead to cracking and loss of strength, not all expansive reactions are detrimental. Expansion of phases within gel porosity is more damaging than phase formation in larger pores . Phase formation arises from chemical reactions between locally available constituent ions. Consequently, the deterioration of concrete through expansive phase formation must involve: mass transport (constituent ions and water) (Project 4), chemistry (Project 1), suitable crystallisation environment (e.g. confined space) and appropriate crystal orientation relative to the pore wall.
Objective and Innovation : The project will characterise the impact of expansion at the nano-microstructural level by characterising the mechanical properties of pore wall materials and crystal growth pressures. Such information will provide the link between models of the physico-chemical processes of phase formation and the macroscopic models which predict mechanical properties of concrete. Collaboration with Oxand will enable application of the fundamental knowledge concerning expansive reactions to the practical model developed in project 9, and study of the mechanical behaviour of a material subjected to expansion reaction product in a limited pore and void volume.

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