Monitoring the interaction of multiple mode deterioration mechanisms in concrete

• Main Author: Backus, Jonathon
• Published: Queen's University Belfast 2014
• Subjects: 620.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669541

The current Eurocodes (British Standards 2005b) and American Standards (ACI Committee 318 2004) stipulate single deterioration mechanism design that caters to the worst case scenario, However, in certain environments such as coastal structures and road structures where de-icing salts are used, combinations of chlorides, sulfates and carbon dioxide are possible. Thus as current codes of practice provide no guidance on how to deal with multiple modes of deterioration this is the main subject of this thesis, In this research project the effects of combined deterioration mechanisms in concrete have been measured over time, Although the effects of chloride, carbon dioxide ingress have been widely researched previously, their interactions and effect on durability of concrete has not been comprehensively covered for common cementitious materials, In this study an accelerated exposure regime was established, This allowed the interactions between carbon dioxide and chloride, and chloride and sulfate, and their effects on the concrete to be assessed. The progression was measured using the following techniques: chloride, sulfate and pH profiles, phenolphthalein indicator, Autoclaim air permeability, compressive strength and X-ray diffraction analysis, It has been shown that combined mechanisms can occur and can have a detrimental effect on the durability of concrete, Thus structures designed to the current standards may deteriorate prematurely, It is recommended that further research is carried out to check that the experimental data correlates with results for existing structures, If these trends hold true then the standards need to be updated to account for these interactions,