USE OF INDUSTRIAL BY-PRODUCTS AS MINERAL POWDERS IN ROAD CONSTRUCTION

Introduction. Mineral powder is an important structural component of asphalt concrete. Mineral powder is the output material obtained after crushing of rocks or powdery remains of the industry. It is made by grinding the following hard rocks: dolomitized limestone, dolomite, limestone. Non-carbonate raw materials and industrial wastes are also used as raw materials. Problem statement. Road construction with the arrangement of asphalt concrete pavements requires a number of components of these mixtures. Due to this, the need in scarce carbonate mineral powders is growing. Therefore, it is advisable to consider researches directed on studying a number of by-products of industry in order to use them as a mineral powder of asphalt concrete. Purpose. To analyze the existing experience of using industrial waste as a mineral powder in production of asphalt concrete mixture for further introduction and improvement of environmental safety and operational characteristics of pavement due to new road construction materials. Materials and methods. Analysis of information sources and experience in the use of industrial waste as a mineral powder and study of requirements for materials and their composition. Results. An analytical review of the experience of using industrial waste as a mineral powder was performed. Various materials have been studied and analyzed, requirements for materials, their particle size distribution, content in asphalt concrete mixture had been established. Conclusions. Analysis of information sources regarding use of industrial waste as a raw material for the production of mineral powder had determined that they are used in the whole volume in different countries and in most cases in road construction. It had been found that the use of various wastes during road construction is a viable option that needs further study.

Structured asphalt binder is a new binder type in asphalt concrete mixtures

The data presented in the article are part of disserta-tion research on the formula development and pro-duction principle of composite material for road con-struction with phosphogypsum and secondary poly-ethyleneterephthalate use. The article provides an assessment of the existing most successful and effec-tive technologies for creating asphalt concrete pave-ments with high technical performance characteris-tics, and the key role in formula is an asphalt binder on the binary system mineral powder/oil road bitu-men basement, their main advantages and disad-vantages are described. A new technological method for the asphalt concrete mixtures production is de-scribed - pelletization by rolling, which was proposed by the authors. The paper presents the study's results to determine the structured asphalt binder technical and operational properties obtained by the method of pelletization by rolling. A brief theoretical substantia-tion of the physicochemical nature of improving a number of developed composition technical and op-erational characteristics of a structured asphalt binder is presented. The dynamics of over time changes in the main structured asphalt binder indicators, from 2005 to 2019, are given. It has been theoretically proven that in a structured asphalt binder obtained by the method of pelletization by rolling, bitumen is in a film state, and the bitumen interlayers thickness be-tween the mineral powder particles is of the order of 100 nm, which makes it possible to classify the prod-uct as a nanomaterial and determines its special properties set. The data of independent and our own experimental studies are also presented, indicating the previously obtained theoretical justification correct-ness for increasing the strength indicators, improving the water saturation indicators, and the water re-sistance coefficient. The absence of negative changes in the main technical and operational properties dy-namics for 14 years confirms the possibility of storing the mixture in a cold form outside a sealed package in an unheated room, which makes it possible to assert the possibility of preparing material for future use and transporting it over unlimited distances.

Structured asphalt binder is a new binder type in asphalt concrete mixtures

The data presented in the article are part of disserta-tion research on the formula development and pro-duction principle of composite material for road con-struction with phosphogypsum and secondary poly-ethyleneterephthalate use. The article provides an assessment of the existing most successful and effec-tive technologies for creating asphalt concrete pave-ments with high technical performance characteris-tics, and the key role in formula is an asphalt binder on the binary system mineral powder/oil road bitu-men basement, their main advantages and disad-vantages are described. A new technological method for the asphalt concrete mixtures production is de-scribed - pelletization by rolling, which was proposed by the authors. The paper presents the study's results to determine the structured asphalt binder technical and operational properties obtained by the method of pelletization by rolling. A brief theoretical substantia-tion of the physicochemical nature of improving a number of developed composition technical and op-erational characteristics of a structured asphalt binder is presented. The dynamics of over time changes in the main structured asphalt binder indicators, from 2005 to 2019, are given. It has been theoretically proven that in a structured asphalt binder obtained by the method of pelletization by rolling, bitumen is in a film state, and the bitumen interlayers thickness be-tween the mineral powder particles is of the order of 100 nm, which makes it possible to classify the prod-uct as a nanomaterial and determines its special properties set. The data of independent and our own experimental studies are also presented, indicating the previously obtained theoretical justification correct-ness for increasing the strength indicators, improving the water saturation indicators, and the water re-sistance coefficient. The absence of negative changes in the main technical and operational properties dy-namics for 14 years confirms the possibility of storing the mixture in a cold form outside a sealed package in an unheated room, which makes it possible to assert the possibility of preparing material for future use and transporting it over unlimited distances

The Effect of Mineral Powder on the Surface/Interface of Aggregates and Asphalt

This paper attempts to analyze the effect of mineral powder on the adhesion of aggregates and asphalt. First, it employs the gravimetric method to quantitatively analyze the peeling rate of asphalt and asphalt mortar from the surface of basalt, andesite, and limestone aggregates. Then, it takes microscopic pictures of the mineral powder adhered on the surface of the aggregates to observe the distribution of mineral powder in the asphalt mixtures, and uses profiles to analyze the adhesion status of mineral powder on the surface of the aggregates. At last, this paper analyzes the effect of mineral powder particles on the surface/interface of the aggregates and asphalt, and the results indicate that mineral powder has increased the roughness of the surface of the aggregates, therefore it indirectly promotes the adhesion of asphalt on the surface of the aggregates; the mineral powder particles interact with the surface texture of the aggregates, forming an embedding and wedging structure in the texture; compared with aggregates with smooth surface, the adhesion promotion effect is stronger.

Analysis of Nanoindentation Test Results of Asphalt Mixture with Different Gradations

Nanoindentation has been applied in the field of asphalt mixtures, but, at the nano-scale, changes in the composition of the mixture and material properties can have a significant impact on the results. Therefore, it is necessary to investigate the feasibility of nanoindentation tests on different types of asphalt mixtures with different gradations and the influence of material properties and test methods on nanoindentation results. In this paper, the nanoindentation test results on three kinds of asphalt mixture (AC-13, SMA-13, and OGFC-13) with different aggregate gradations were investigated. The load-displacement curves and moduli obtained from the nanoindentation tests were analyzed. In addition, nanoindentation tests were carried out before and after polishing with different ratios of filler and asphalt (RFA) (0.8–1.6). On this basis, the morphology of asphalt specimens with different RFAs is observed by scanning electron microscopy (SEM) imaging. The results indicate that using the nanoindentation test to characterize the mechanical behavior of asphalt mixture, the confidence level of the dense-graded mixture is low, and non-dense-graded mixtures are used as much as possible. Moreover, results illustrate that the nanoindentation modulus tends to increase as the RFA increases. and the SEM chart shows that the higher the mineral powder content in the mastic, the more complex the bitumen and mineral powder interaction surface, confirming the influence of mineral powder content on the nanoindentation test results. Furthermore, the effect of polishing is almost insignificant.

Biopositive Technologies Applied to the Management of Road-building Waste of Different Origin

The basic principles of management of road-building waste of different origin have been presented. The research findings by applying the method of analytical hierarchy have been presented to preliminary evaluate the bio-positivity of the proposed methods of waste management. The research findings in the field of the hydrophysical and physicomechanical properties of asphaltic-cement concrete partially replacing mineral powder by entrainment dust have been presented. The heterogeneous waste processing and recycling project has been proposed.

Evaluation of the Effects of Filler Fineness on the Properties of an Epoxy Asphalt Mixture

The type and fineness of a filler significantly affect the performance of an asphalt mixture. There is a lack of specific research on the effects of filler fineness and dust from aggregates on the properties of epoxy asphalt (EA) mixtures. The effects of aggregate dust and mineral powder on the properties of an EA mixture were evaluated. These filler were tested to determine their fineness, specific surface area and mineral composition. The effects of these fillers on the EA mastic sample and mixture were evaluated. The morphology of the EA mastic samples was analyzed using scanning electron microscopy (SEM). The effects of the fillers on the Marshall stability, tensile strength and fatigue performance of the EA mixture were evaluated. The dust from the aggregates exhibited an even particle size distribution, and its average particle size was approximately 20% of that of the mineral powder. The SEM microanalysis showed that the EA mastic sample containing relatively fine dust formed a tight and dense interfacial bonding structure with the aggregate. The EA mixture sample containing filler composed of dust from aggregate had a significantly higher strength and longer fatigue life than that of the EA sample containing filler composed of mineral powder.