The Laboratory of Geomaterials was first established by Professor Ioannis Vardoulakis in 1997. Two triaxial (basic and advanced) and one biaxial apparati were bought from research funding and financial support of the Section of Mechanics, Department of Applied Mathematics and Physics, National Technical University of Athens. The Laboratory of Geomaterials is fully operational since the end of 2004. The installation of the above apparati was completed during the PhD thesis of Dr Georgopoulos Ioannis-Orestis, under the supervision of Professor Ioannis Vardoulakis. In view of the increased laboratory needs and current experimental updates, the laboratory has been refurbished. The current version of GeoLab includes a newly designed pressure panel distributor (17.5Mb) (air, CO2, N2, vacuum and water-lines) a basic and an advanced triaxial apparati and one biaxial apparatus. Two data loggers have been constructed for monitoring and controlling the above mentioned apparati. The position of the apparati and the rest of the GeoLab infrastructure has been redisgned so as to maximize the laboratory efficiency.
Current apparatus updates
The effort is mainly focused on the modification of the advanced triaxial apparatus. The Wykeham Farrance triaxial cell is modified in such a way that the upper and lower loading plates move parallel to each other during a test and at the same time the axial load eccentricity is aslo monitored. The triaxial cell also supports on-sample transducers, which allow direct measurement of the axial and radial strain of the specimen. The design also includes the installation of an hypodermic needle, which will allow for monitoring of the pore water pressure inside the sample.
Current experimental research in the Laboratory
From the beginning of 2005, common triaxial compression tests in Hostun Sand S28 have been performed in the basic-3xl apparatus. The results have been qualitatively and quantitatively compared with others from so-far well established laboratories (Laboratoire 3S, Grenoble, France, Prof. Desrues Jacques) so as to verify the testing capabilities of the apparatus. Special attention is also paid at grain crushing phenomena. The study of the mechanical behavior of granular materials with soft grains is performed through detailed experimental tests, which include special stress paths in triaxial and biaxial apparati.