Experimental characterization of mechanical properties of the cement pasteaggregate interface in concrete

• Main Authors: Jebli M., Jamin F., Malachanne E., Garcia-Diaz E., El Youssoufi M.S.
• Format: Article
• Language: English
• Published: EDP Sciences 2017-01-01
• Series: EPJ Web of Conferences
• Online Access: https://doi.org/10.1051/epjconf/201714012014

Granular materials are extensively used in the field of civil engineering. These materials are either used in their dry state, or mixed with water or with a binder. In the case of concrete, the binder could be cement or mortar. For ordinary concretes, it is generally admitted that there is a thin heterogeneous zone of paste, with a thickness of about 15-60 μm, surrounding the aggregates surface. This zone, commonly named the Interfacial Transition Zone (ITZ), is characterized by a higher porosity than the bulk paste and a high concentration of the portlandite crystals. Some of these crystals react with the aggregates’ surface (limestone aggregates), leading to a good adhesion. In this work, the mechanical properties of the cement paste and of the cement-aggregate interface are experimentally analyzed. Experimental tensile and shear tests are performed on parallelipipedic samples. These samples are made by linking limestone aggregates with Portland cement paste using a water / cement ratio of 0.5. The results show that the cement-aggregate interface is the weak zone in the composite.