Sampling in coarse granularity materials frequently causes problems since relatively large sample masses are required for the samples to be representative of the material in question. The objective of the experiments reported here has been to develop a method for sampling in roadbases and sub-bases primarily for production control and quality control after production. Sampling in roadbases has been performed in two different materials laid in one of the VTI test road halls. The materials were chosen so that one was at the lower limit of the roadbase zone of BYA (Swedish Road Administration Specifications), while the other was at the upper limit. Sampling in sub-bases was performed in two road construction projects. In both cases, the material had a maximum grain size of about 200 mm. Sampling was performed primiarily on laid and rolled material, but less extensive sampling was also carried out in stockpiles and directly from a conveyor belt. When sampling in sub-bases, field sieve analyses of material larger than 20 mm were performed to a great extent. Certain preparatory experiments were performed with the aid of image analysis (photographs from field of compacted material). Finally, a proposal concerning "A method for sampling roadbase and sub-base layers" is described. (A)
Abstract