Abstract
In order to prevent or at least reduce the deformation of road surface, it is necessary to ensure adequate water permeability of the structural layers and control of groundwater level. In geotechnical engineering, the water permeability of the mineral aggregates or soils is determined using a constant head water permeability apparatus. In order to assess the suitability of the results, it is necessary to take into account particle size distribution of the test object and perform the test at different hydraulic ramps. The aim of this research is to define and clarify unbound mineral aggregate mixtures hydraulic gradient and compaction level of road layer impact on water permeability. The following properties have been determined during the tests: particle size distribution, particle density, Proctor density, optimum water quantity, water permeability under different compaction and hydraulic slopes. Based on the results of the research, low-dustiness non-bonded mineral materials are recommended for frost resistant layers. For the water-permeability coefficient test, it is recommended that the test layer should be compacted to a design compaction ratio and the hydraulic gradient should not be higher than 1.0. Other conclusions and recommendations for further research and for improvement of water permeability functionality in the road pavement are presented.
Highlights
When designing a road pavement structure, it is important to evaluate the maximum permissible vertical tension on the surfaces of the unbound base and subgrade layers by reducing the permissible deformations
Water permeability test results shows that the values of the washed sand are 3 times the value of the non-washed sand when the compaction rate is optimal; when the compaction rate is 103%, the value of the washed sand water permeability coefficient are 7 times the value of the non-washed sand
The results show that a 2% increase in mineral dust in the mixture has a significant impact on water permeability
Summary
When designing a road pavement structure, it is important to evaluate the maximum permissible vertical tension on the surfaces of the unbound base and subgrade layers by reducing the permissible deformations. It has been recognized that the performance of flexible and rigid pavements is closely related to the characteristics of unbound layers and subgrade. The main functional parameters (tension and deformation) of the non-rigid pavement constructions are highly dependent on the properties of cold-resistant layers and subgrade soil. A large part of the pavement surface deformations are conditioned by inadequate subgrade layer and its bearing capacity due to excessive water content. Raised groundwater level increases both the resilient and the permanent strains in all unbound layers above groundwater level in the pavement structure [2]
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