The research project presented here includes the development and construction of a new robust and reliable long-time swelling testing device. The influence of external factors on the test as adjustment of loads, long-time accuracy of measurement, stiffness of the testing device or temperature should be eliminated or minimised. With this new testing apparatus and with samples from the Chienberg tunnel, i.e. dehydrated rock from the gypsum keuper, series of swelling tests under different axial loads should be performed. The duration of each test is estimated up to 10 years. The measurements should deliver information about the time development of the swelling process and in particular about the influence of pressure and on the long-term swelling strain.