The paper provides a brief presentation of laboratory investigations of concrete and its components that have so far been performed at the Albanian Construction Institute in Tirana and reflect the Albanian construction practice. Selected results from compressive tests of three concrete mix proportion, (normal, intermediate and high strength) prepared with five different types of cements are presented. In order to study the influence of different concrete classes on dynamic behavior and seismic resistance of buildings, analytical investigations of the seismic response of models of RC buildings have been carried out.