Introduction. Mastic asphalt concrete is one of the oldest road construction materials used for road pavements.
Problem Statement. Mastic asphalt concrete is a type of hot asphalt concrete, a feature of which is an increased amount of mineral powder and bitumen binder, due to which mastic mixtures can be placed in the road surface without compaction. Therefore, one of the main technological indicators of the quality of mastic asphalt mixtures is their fluidity. This indicator is one of the most important for designing the composition of the mastic asphalt mix, establishing the optimal amount of bitumen binder and setting the technological temperatures for preparing the mix at the plant and placing it in the road surface. Despite this, this indicator is not currently defined or standardized in the domestic road industry.
The purpose. The aim of the study was to review the method for determining the plasticity of mastic asphalt mixtures based on the immersion depth of the test rod, as well as to establish the possibility and feasibility of its use for assessing the quality of mastic mixtures.
Materials and methods. The object of study is the method for determining the plasticity of mastic asphalt mixtures based on the immersion depth of the test rod, which is used in European countries to select the composition of mastic mixtures and establish the optimal temperature conditions for their manufacture and paving. The method of determining plasticity was tested on a mastic asphalt mixture LABS-10 made on BND 35/50 bitumen, the composition and properties of which meet the requirements of current national regulatory documents.
Results. The article presents the results of testing a method for determining the plasticity of a mastic asphalt mixture based on the immersion depth of the test rod. The advantages and disadvantages of this method and the device used to determine the plasticity of the mixture are identified, and further steps to improve it are outlined. On the basis of experimental verification of this method, its sensitivity to the composition of mastic asphalt mixtures and their production temperature was determined. It has been established that a comprehensive assessment of mastic asphalt mixtures in terms of technological and operational plasticity makes it possible to determine the optimal content of bituminous binder at the design stage of the mastic mixtures composition and to assign the most rational temperature regime for the preparation and placement of mixtures.
Conclusions. On the basis of experimental verification of the method for determining the plasticity (mobility) of mastic asphalt mixtures based on the assessment of plasticity by the depth of immersion of the test device (plunger, rod, hammer) in the mixture, the possibility and expediency of its use for: designing the composition of mastic mixtures; selecting the optimal amount of bitumen and establishing acceptable technological temperatures for the preparation and placement of mixtures were established.
