Effect of Grouting on the Resistance of Portland and Blast Furnace Slag Cement Paste Against Chemical Attack by Aggressive Carbon Dioxide

Chemical attack by aggressive carbon dioxide on cement-based materials is of major concern for foundations of engineering structures with long service life. The exposure in natural groundwaters leads to dissolving attack, where all hydration products are deteriorated. The resistance of cement-based materials increases therefore with a low porosity and a high content of inert aggregates. For ground anchors cement suspensions are grouted during the manufacturing process. In non-cohesive soils the mixing water is filtered by the applied pressure. This leads to an improved and dense microstructure. Due to their small dimensions and high tensile load capacity ground anchors can be subjected to a loss of load bearing capacity already in short-term periods because of the attack by aggressive carbon dioxide. This paper investigates the effect of grouting on the resistance of cement paste against the chemical attack by aggressive carbon dioxide. Three cement types CEM I, CEM III/A and CEM III/B are investigated. The object of the investigations are grouted and neat cement paste samples which are prepared in the laboratory and afterwards stored for 3 and 6 months in an aggressive solution with ~ 90 mg CO2 /l. The depth of impact is assessed by polarized light microscopy on thin sections. The results conclude in an assessment of the resistance of the different cement types and an evaluation of the durability for issues in building practice.

Subjects

aggressive carbon dioxide

cement grouting

cement paste

Chemical attack

ground anchor

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Effect of Grouting on the Resistance of Portland and Blast Furnace Slag Cement Paste Against Chemical Attack by Aggressive Carbon Dioxide