MATERIALS RESEARCH ON EPS20 AND EPS15 UNDER REPRESENTATIVE CONDITIONS IN PAVEMENT STRUCTURES

This article deals with the investigation of the mechanical characteristics of EPS with bulk densities of 15 km/cu m (EPS15) and 20 kg/cu m (EPS20) under different hydro-thermal condiitons. In the experiments, the EPS is tested under the expected loading, moisture and temperature conditions defined as critical. It is a guarantee that EPS will show at least an equally good mechanical behaviour in real sub-base conditions under real traffic loading. In the second section, details are given about EPS20 and EPS15 specimens on which the experiments were carried out. The third section deals with hydro-thermal research on EPS. Water absorption of EPS is stimulated by means of immersion, immersion together with exposing to underpressure, and exposing to freeze-thaw cycles. The purpose of the experiments is twofold: firstly, to obtain information on the water absoprtion of EPS under different conditions and, secondly, to prepare samples for further mechanical research. In the fourth section, determination of the dynamic moduli of elasticity of EPS20 by means of propagation velocity of a wave through a prismatic sample is described. The fifth section describes compression tests on cylindrical specimens of EPS15 and EPS20. Compression was performed with different strain rates on the specimens with varied moisture contents. The linear elastic region, evolution of the EPS material modulus and the stress and strain values corresponding to beginning of permanent deformations were determined by results analysis. The experiments were performed at low temperatures too. The minimum test temperature was -13.9 degrees C. Different strain rates, various test temperstaures (only EPS30) and specimen conditions were used to determine the effects, if any, of these test conditions on EPS15 and EPS20 material behaviour. In the scope of uniaxial cyclic loading tests described in the sixth section, samples have been exposed to combined static and dynamic loading. In the seventh section, creep in the EPS sub-base is investigated under static stresses, which represent dead weights of thin and thick overlaying layers above an EPS sub-base. Finally, in the last section, overall conclusions for this research on EPS15 and EPS20 are drawn. (A)