POLYMER ASPHALT CONCRETE, IT’S PROPERTIES, TEST METHODS AND QUALITY ASSURANCE
IntroductionAsphalt concrete is a dispersed system, where the solid phase appears as a compound of mineral particles. The liquid phase is bitumen. Asphalt concrete is also considered coagulated structure. However, this understanding should me made more precise: asphalt concrete and other organic concretes based on organic binding material with coagulated structure are dispersed systems, where the dispersed phase is made up of mineral materials, which adsorbed on their surface and in their pores part of the components of the binding substance, as well as particles of the binding substance’s dispersed phase, whereas the dispersion media (liquid phase) is the dispersion media of the binding substance. In this regard, the future may require serious research directed at the influence of the composition and properties of the dispersion media of bitumen, polymer bitumen binders and other organic binding materials on the properties of asphalt concrete, polymer asphalt concrete and other organic concretes.
Comparison of polymer asphalt concrete and asphalt concrete propertiesParticular properties of polymer binding substances are well demonstrated in process and operational properties of polymer asphalt concrete mixes. Polymer based mixes have the best compactability. The optimum of compactability lies in the cold temperature range, regardless the viscosity of bitumen used, that is, the mix compacts well at lower temperatures. In this case we obtain a material with somewhat different pore structure. The difference between residual porosity and water saturation, which characterized the volume of closed pores in polymer mixes, is 20 – 30% higher than that of bitumen, which can be inferred from the table below. Polymer asphalt concrete satisfies all of the requirements related to hot asphalt concrete by the relevant standards and has higher deformability (which is indirectly indicated by lower durability at 0°C), higher durability at 50°C, water and cold resistance. The most indicative characteristic, which allows detection of the difference of polymer asphalt concrete from asphalt concrete, is the temperature sensitivity coefficient. Polymer asphalt concrete is much less sensitive to temperature changes.
Table 1. Mechanical properties of type D polymer asphalt concretes