DETERMINING MATERIAL PARAMETERS CONCERNING THE DESIGN OF CONCRETE PAVEMENTS

This paper reports on a research project, carried out at the Chair of Pavement Engineering at the Dresden University of Technology, which aimed at determining material parameters concerning the design of concrete pavements. Thereby the feasibility of assessing the tensile strength by way of indirect tensile strength was investigated. The latter was used as input data for the analytical design of concrete pavements respectively the calculation of the loading capacity of the pavement. Static and dynamic tests were conducted to answer questions concerning different parameters. The obtained results showed that the particle top size as well as the source of the core specimen affected the dependency of the indirect tensile strength on the layer location. Short specimens were used preferably due to the possibility of uneven surfaces and the corresponding stress peaks. In particular the testing of two-layer concrete might have generated wrong results for specimens of great height as specimens composed of several layers possibly featured varying compaction characteristics. Furthermore it could be confirmed that the indirect tensile strength decreased for increasing specimen diameters independent from the particle top size. The investigation showed that the usage of concavely bent loading strips resulted in a higher strength at a lower coefficient of variation compared to even loading strips. Recordings with a high speed camera proved the material failure to be due to tensile stress in spite of existing cracks deriving from shear stress. Thus the type of failure could not be reasoned from the fracture pattern observable at the end of the test.

• INTRODUCTION

• METHODS FOR INVESTIGATION OF THE TENSILE STRENGTH

• DESIGN OF EXPERIMENTS

• EXAMINATION OF THE TEST CONDITIONS

• TEST EVALUATION

• SUMMARY

• REFERENCES