Application of micro X-ray diffraction to investigate the reaction products formed by the alkali–silica reaction in concrete structures

• Published in: Cement and concrete research Vol. 79
• Main Authors: Dähn, R., Arakcheeva, A., Schaub, Ph, Pattison, P., Laboratory of Crystallography, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Chapuis, G., Grolimund, D., Wieland, E., Leemann, A.
• Format: Journal Article
• Language: English
• Published: United States 15.01.2016
• Subjects: CONCRETES; MATERIALS SCIENCE; SPATIAL RESOLUTION; X RADIATION; X-RAY DIFFRACTION
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/J.CEMCONRES.2015.07.012

Alkali–silica reaction (ASR) is one of the most important deterioration mechanisms in concrete leading to substantial damages of structures worldwide. Synchrotron-based micro-X-ray diffraction (micro-XRD) was employed to characterize the mineral phases formed in micro-cracks of concrete aggregates as a consequence of ASR. This high spatial resolution technique enables to directly gain structural information on ASR products formed in a 40-year old motorway bridge damaged due to ASR. Micro-X-ray-fluorescence was applied on thin sections to locate the reaction products formed in veins within concrete aggregates. Micro-XRD pattern were collected at selected points of interest along a vein by rotating the sample. Rietveld refinement determined the structure of the ASR product consisting of a new layered framework similar to mountainite and rhodesite. It is conceivable that understanding the structure of the ASR product may help developing new technical treatments inhibiting ASR.