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Last update 30/05/2007

Task 2_2:- “New material treatment techniques”

Lead Contact

Pauli Kolisoja - Tampere University of Technology

Nuutti - Tampere University of Technology

Objective

Task 2_2 of the Roadex II Project deals with the available methods that can be used in improving the performance of the structural layers, especially the base course layer, of the low volume roads in the Northern Periphery (NP) area. The main emphasis is on the so called non-traditional treatment agents and methods that can potentially provide cost-effective alternatives to the traditional stabilisations performed using hydraulic and bituminous binding agents. Since the main problem, to which the new material treatment methods are being applied, is permanent deformations on low volume roads, the task has been done in close co-operation with Task 2_1 ‘Permanent deformation’.

Outputs

The final report of Task 2_2 attempts to make a concise summary of the current knowledge concerning the types of non-traditional treatment agents available and to assess their applicability in treating the base course materials of low volume roads in the NP area.

In the beginning of the report a short summary of the typical climatic conditions and the related problems on the low volume road network in the NP areas is given. After that an overview of the currently available stabilisation and treatment methods is made. Special attention is given to the non-traditional treatment agents and the various types of classifications presented for them in the literature. Further, a classification applicable to the materials typically used in the base courses of low volume roads in the NP area is suggested. Based on that classification, the primary influence mechanisms of the various types of non-traditional treatment agents are considered.

The experimental results presented in this report include Tube Suction (TS) tests and repeated load triaxial (RLT) tests with four Finnish, one Norwegian and one Swedish test material. The TS test is used as a simple to perform test method to assess the water suction properties of the various types of base course materials and the effect of different treatment agents on them. The RLT tests have been done according to a special test procedure attempting to simulate the effect of seasonal variations on the mechanical behaviour of the base course materials.

Both the results of TS and RLT tests indicate that even a fairly small amount of bitumen, 2 to 3% and in some cases only 1%, can markedly reduce the water suction tendency of a problematic base course aggregate and thus improve its performance under a repeated loading corresponding to the effect of heavy vehicles even during the thawing period of seasonal frost. The results obtained with the non-traditional treatment agents were twofold. Some of the treatment agents did not indicate any positive effect while some of them seemed to have great potential as alternatives to traditional stabilisation methods. Concerning many of the negative results it must be noted, however, that the tests were done even with treatment agents that, according to the information provided by the manufacturers, could only be expected to be effective with materials having a much higher fines content than what is typical for the base course materials in the areas of seasonal frost.

Links

Tampere University of Technology

Acknowledgments

Research Assistants Timo Raitanen and Mirko Harjula and Laboratory Technician Marko Happo.