This IP reports on a programme of uniaxial compression tests on concrete specimens to determine the effect of concrete grade on volumetric strain and to compare short-term and long-term loading capacity. Uniaxial compression tests were carried out on concrete prisms made from concrete grades ranging from normal to very high grade (C40, C70 and C130). Axial and lateral strains were measured, thus giving the volumetric strain. The applied stress carried at minimum volume, as determined from these short-term tests, was compared with the long-term strength of concrete under sustained loading, and the effect of concrete grade was studied. The results were also used to investigate the power curve for stress-strain relationships, and simple formulae for the initial stiffness and Poisson's ratio were obtained. 6 pages.