It is known that there are significant deposits of lignite (brown coal) in Ukraine, particularly in categories A + B + C1. At the same time, certain technical and legal obstacles limit its use as an energy carrier. Therefore, new methods of using lignite and processing its products are necessary. The latter includes humic acids. It was suggested that these acids could be used to stop road bitumens from breaking down. This is because they are antioxidants that contain functional phenolic and carboxyl groups. In particular, this article analyses the nature of the influence of humic acids on the physical and mechanical properties of road petroleum bitumen and its resistance to technological aging. It was found that at a modification temperature of 120 °C (duration-60 min., consumption of humic acids-2.0 wt.%), this additive has a slight negative effect (changes are within permissible limits) on the plastic properties of bitumen and slightly improves its elasticity. The main reason for adding humic acids to road bitumen under the specified conditions is to improve its resistance to technological aging compared to the original binder.
Aging peculiarities of paving bitumen, which was obtained by different ways, have been studied. Oxidized and residual bitumen produced from oils of Ukrainian deposits were used and the changes in the main characteristics of bitumen after 5 and 10 h of aging in a thin film at the temperature of 436 K have been determined and the processes occurred during the aging have been studied. Using infrared spectroscopy, the changes in the structural composition of the binder during aging have been analyzed.
Using a relatively inexpensive method, phenol–cresol–formaldehyde resin (PhCR-F) was produced utilizing the byproducts of coal coking. It is shown that petroleum road bitumens, to which 1.0 wt.% PhCR-F is added, in terms of basic physical and mechanical parameters, comply with the requirements of the regulatory document for bitumens modified with adhesive additives. Research on the operational properties of these modified bitumens as a binding material for asphalt concrete is described. It has been proven that modified bitumen can store stable properties during its application (resistance to aging). The interaction of bitumens modified by PhCR-F with the surfaces of mineral materials, which occurs during the creation of asphalt concrete coatings, was studied. It was shown that adding 1.0 wt.% PhCR-F to road bitumen significantly improves the adhesion of the binder to the mineral material and increases the hydrophobicity of such a coating. The production of effective bitumen modifiers from non-target coking products of coal will not only make it possible to use new resources in road construction but will also increase the depth of decarbonization of the coking industry.
This paper discusses the main features of technological aging of bitumen, in particular, the mechanisms and transformations that accompany this process. The main laboratory methods for modeling the above processes are considered. It is described how the technical essence of the methods has changed from the first developments to the present. A number of compounds that can be used as inhibitors of technological aging, including antioxidants and plasticizers, as well as some “natural” substances that have these properties, are presented.
20 September 2023 in Chemistry & Chemical Technology
The possibility of using potassium humate as an inhibitor of the technological aging of oxidized petro-leum bitumen has been investigated. Samples of potas-sium humate obtained from various raw materials, in particular peat and leonardite, were selected and compared. Aging coefficients have been calculated and operational properties of modified bitumen as a binding material for hot mix asphalt have been investigated. It was established that 3.0 wt. % of PH-3 added to oxidized petroleum bitumen, slows down the technological aging processes and allows obtaining asphalt concrete with better characteristics compared to the coating made on the basis of unmodified bitumen.
1 June 2023 in Voprosy Khimii i Khimicheskoi Tekhnologii
The effects of the technological process of aging of bitumen obtained from the residues from processing of Ukrainian crude oil on the bitumen’s operational characteristics, structural-group composition, and thermal stability have been studied. The aging of bitumen with a thickness of 2 mm has been conducted under laboratory conditions at a temperature of 1630C for 5 and 10 h. Two types of bitumen, oxidized bitumen BND 60/90 and distillation bitumen BD 130/200, have been examined. It has been found that the bitumen quality worsens due to the technological process of aging, e.g. the bitumen hardness and refractoriness increase whereas the elasticity and frost resistance decrease. It has also been shown that, because of the technological process of aging, the content of resins in the bitumen decreases, the content of asphaltenes increases, and the content of oil components does not change significantly. The structural type of the oxidized bitumen changes thereat from a "sol–gel" type to a "gel" type. For the distillation bitumen, the structural type does not change. The derivatographic analysis has revealed that the bitumen thermal stability increases due to the technological process of aging. The reason for this is a decrease in the content of paraffinic ingredients in the bitumen along with the bitumen structure compaction due to the aging.