Introduction. One of the aspects of Ukraine's European integration is the introduction of European approaches to the design of asphalt mixtures. In Ukraine, as in other European countries, when designing the asphalt mixtures, asphalt concrete samples are made by compaction in the laboratory; however, different compaction methods are used for this purpose.
Statement of the problem. In Ukraine, the method of compaction of asphalt mixtures in the laboratory at a pressure of (30.0 ± 0.3) MPa is used if the crushed stone content in the mixture is higher than or equal to 35%, or at a pressure of (40.0 ± 0.4) MPa if the crushed stone content in the mixture is up to 35%. In the countries of the European Union, the Marshall impact compaction method of 100 strokes (50 strokes on each side) is mainly used for this purpose. Therefore, it is advisable to determine the effect of the method of compaction of asphalt mixtures on the volumetric properties of asphalt concrete, depending on the largest nominal grain size of the aggregate and the compaction method.
Objective. To determine the dependence of the volumetric properties of asphalt concrete on the largest nominal grain size of the aggregate and the compaction method.
Materials and methods. Analysis of literature sources and laboratory research.
Results. With an increase in the bitumen content, there is a decrease in the maximum density of the asphalt mixture and an increase in the bulk density of asphalt concrete. The increase in the bulk density of asphalt concrete is associated with both improved compaction of the asphalt mixture as a result of an increase in the bitumen content and more filling of air pores, as evidenced by the values of the pore content in the mineral aggregate. The only exception is the AC 16 asphalt mixture, for which the values of the pore content in the mineral aggregate remain unchanged, i.e. in this case, the increase in bulk density is due exclusively to the filling of pores in the mineral aggregate. The largest nominal size of the aggregate in the asphalt mixture affects the total pore content of the mineral aggregate. This suggests that the increase in the required bitumen content in the asphalt mixture with a decrease in the largest nominal size of the aggregate is largely due to the need to fill more pores, rather than to an increase in the total specific surface area of the aggregate.
Conclusions. The volumetric properties of asphalt concrete depend on the bitumen content in the asphalt mixture and the largest nominal aggregate size. An increase in the bitumen content leads to a decrease in the maximum density of the asphalt mixture, residual porosity and water saturation of the asphalt concrete, as well as an increase in the content of pores filled with binder. At the same time, the bitumen content has virtually no effect on the percentage of pores in the mineral aggregate. A decrease in the largest nominal size of the aggregate leads to an increase in the percentage of pores in the mineral aggregate.
