Mineral carriers for nanoscale additives in bituminous concrete

To prolong the lifetime and to improve the quality of pavements made of bituminous concretes it is necessary to apply innovative solutions during design of such building materials. The common way to increase the values of operational properties is to admix various modifying additives during production. Nanoscale additives currently constitute the big group of advanced modifiers. The known difficulty limiting the widespread practical use of nanotechnology is the necessity to ensure uniform distribution of nanoscale objects in the volume of material. Thus, to realize nanotechnology in construction it is necessary to use the various carriers for nanoscale modifiers. Several mineral materials (dolomite- and silica-based) were examined and results are presented in this paper. The optimal grain size is determined and optimal modes of grinding were identified to provide conformity of structural parameters for carriers. It is shown that total surface area of diatomite obtained by means of nitrogen absorption method is quite high due to structure of its pore space. It is stated that for structure with numerous contacts between grains, rheological properties of mixture are mostly determined by the thickness and properties of solvation shells on the grains. High surface activity of diatomite is confirmed by the rheology data. It is shown that there is the formation of adsorption layer during interaction between bitumen and surface of diatomite, and thickness of this layer is relatively high for the wide range of temperatures. It is found by means of IR spectroscopy that there is only physical sorption of bitumen on the diatomite and no new chemical compounds are forming.