Resistivity Measurements to Assess the Freeze - Thaw Attack on Concrete - Lab Specimen and Real Structure

Abstract

Waterway structures like locks are exposed to a severe freeze-thaw-attack. A sufficient resistance of concrete against this exposure has to be assured. In Germany the concrete for the exposure class XF3 of federal waterway structures has to be tested in the laboratory by the CIF-Test in addition to descriptive requirements. To establish this procedure experiences on concrete mix designs which have been applied in the past were considered as well as research concerning the transferability of laboratory tests to practical experience. One important aspect was a service life study on the degree of water saturation of the concrete under practical conditions in combination with the temperature exposure. The paper presents the results of freeze-thaw tests on lab specimens and cores of concrete elements stored differently and tested at different ages. For a better understanding of the processes of the freeze-thaw attack during the freeze-thaw tests monitoring data of resistivity has been analyzed and compared to hardened concrete properties. The water absorption inside the specimen during capillary suction and the freeze-thaw-cycles could be monitored at different distances to the surface. Correlations of the water absorption to the initiation and development of internal damage were observable. A consideration of the results of the freeze-thaw tests and the resistivity measurements enables a better evaluation of long-term resistivity monitoring data of a lock. It allows for an assessment of the transferability of results of the CIF-Test to practical experience.

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