Investigations of durability on concrete samples reinforced by alkali resistant and non alkali resistant glass fibers: Fid-Bau Portal

Investigations of durability on concrete samples reinforced by alkali resistant and non alkali resistant glass fibers

Kretzschmar, F. / Häußler, F. / Hempel, R. / Franzke, G.

The use of long fibres as a reinforcement of concrete allows a reduction of the fibre content. The use of ARG (alkali resistant glass) fibre reinforcement (polymer modified matrixes) is an attempt to provide the industry with special material systems. By using media-resistant reinforcing materials (ARG fibres or carbon fibres) the media influences can be drastically reduced. For optimising new technologies in civil engineering, the description of time dependent hydration process of cement pastes requires non destructive methods. The ARG fibres are in a direct contact to the cement paste. Therefore interactions (chemical, solution) between the fibre surfaces and the hydrating cement must be considered. This interfacial transition zone creates a special region for specific chemical reactions as well as crystalline phase transformations. The contact between the glass fibre surface is studied by non destructive testing methods (e.g. Impact-echo, Ultrasonic Pulse with Transmission Technique, Infrared Thermography). The instruments scanning electron microscope (SEM) as well as the environmental scanning electron microscope (ESEM) are used for imaging the morphological characteristics of the interfacial transition zone around the fibre surfaces. The objective of the small-angle neutron scattering (SANS) investigations is the non destructive study of the hydrating cement paste influenced by the embedded glass fibres. The structural changes of the cement start with the onset of hydration and could be assumed as an asymptotic process. Hence it is necessary to investigate the same sample over a long time. Monitoring the changes of the scattering curve parameters, it is expected that the presence of the glass fibres (various types) influences the hydration process. The differences in the time dependent hydration mechanism could be observed. SANS gives the possibility to study the hydration process for a tong time by usage of the same sample in dependence on the type of embedded glass fibres.