Contributions for standardisation of plate loading test

The static loading plate tests have been done in different engineering works and particularly in earthwork quality control. At Portugal AFNOR NF P94-117-1 and DIN 18134 standards are frequently used for this purpose. These standards differ on the test protocol and on test interpretation, which reflects on the final elastic modulus obtained. Attempting the importance that this parameter assumes on quality control of embankments layers, there is the need to clarify the interpretation of test results following each standard and to compare their results. In the aim of a national research project POCI/ECM/61114/2004, entitled “Interaction soilrail track for high speed trains”, financed by the Portuguese Foundation for Science and Technology, it was established a protocol between the National Railway Network (REFER) and four national research institutions (University of Minho – UM, National Laboratory of Civil Engineering – LNEC, New University of Lisbon – FCT-UNL and Technical University of Lisbon – IST) to develop the knowledge concerning the methodology for the construction and control of the railway embankments and railtrack layers for high speed trains. One of the objectives of this protocol was the interpretation of results of plate loading tests following standards AFNOR NF P94-117-1 (plate of 600 mm) and DIN 18134 (plate of 300 mm) and the comparison between them, in order to develop a specification of this test to be used as a reference method in Portugal by REFER. To reach this goal it was constructed a trial embankment in the railway of the Évora railway line, about 2,5 km far from railway station of “Monte das Flores”, and a test campaign was performed between October and November of 2006. In the trial embankment materials similar to the ones used on the new Évora railway line were employed. Two types of materials were used: soil, for the embankment layers, and crushed aggregate for the sub-ballast layer (fig. 1). This embankment was constructed above a foundation layer with 0,60 m thickness, compacted in two layers of 0,30 m each. Different layer’s thicknesses (30cm, 40cm, 50cm) and different moisture contents (w-2%, wopt, w+2%) were used for the embankment layers.