Olha Poliak

The research paper provides a detailed investigation of the performance of novel Ukrainian polymer modifiers introduced into an asphalt concrete mixture in a “dry” form during mixing. The experimental study involved the modification of a hot fine-grained, dense asphalt concrete mixture of Type A with a continuous particle-size distribution, Grade I, maximum aggregate size 20 mm, in accordance with standard DSTU B V.2.7-119:2011. According to European standard EN 13108-1, this mixture corresponds to the AC16 surf mixture. The modification was carried out by adding polymer composite additives manufactured in Ukraine to the mineral aggregate skeleton. During laboratory tests, the specific effects of each additive on key physical, mechanical, and strength properties of the polymer-modified asphalt concrete were analyzed, with attention paid to its deformation resistance.

The production of high-quality biodiesel from vegetable oils requires an integrated approach that considers feedstock quality, transesterification, and final product purification. This study investigates a comprehensive technological sequence for soybean biodiesel production combining enzymatic degumming, treatment with biosurfactant-containing microbial culture fluid, cavitation-assisted transesterification, and adsorptive dry purification. Enzymatic pretreatment using the multienzyme preparation Purifine^® 3G in combination with culture fluid obtained from Pseudomonas fluorescens cultivation was associated with reductions in residual phosphorus and sulfur contents and acid value, potentially due to improved enzyme-substrate interactions, although increasing the culture-fluid dosage prolonged phase separation. Cavitation-assisted transesterification produced biodiesel with a higher fatty acid methyl ester (FAME) mass fraction than conventional stirred-reactor processing under the investigated operating conditions, while spectroscopic and chromatographic analyses confirmed the formation of products with similar FAME profiles. A comparative evaluation of three purification schemes demonstrated that direct adsorptive dry purification using natural clinoptilolite provided the highest FAME mass fraction without requiring an additional water-washing step. Industrial-scale testing confirmed the applicability of clinoptilolite-based adsorptive conditioning for reducing residual water content while maintaining a high ester content. Overall, the findings support the technical feasibility of integrating enzymatic feedstock pretreatment, transesterification, and adsorptive conditioning into soybean biodiesel production and identify key aspects for further process optimization and industrial validation.

This study investigates the effect of sulfur allotropy on the phase stabilization of SBS-modified bitumen by directly comparing polymeric (Sp) and rhombic (Sr) sulfur at an identical low dosage of 0.3 wt.%. A 70/100 paving-grade bitumen modified with 3 wt.% SBS-L was used as the reference polymer-modified binder. The addition of sulfur markedly improved storage stability while maintaining enhanced high-temperature performance. The SBS-L binder exhibited pronounced phase separation during hot storage, with a top-to-bottom temperature difference (ΔT) of 2.7 °C. The incorporation of Sp reduced ΔT to 0.4 °C, whereas Sr reduced it to only 0.1 °C, corresponding to reductions of approximately 85% and 96%, respectively. Sulfur-containing SBS binders also showed improved compositional stability after short-term aging, with Sr providing the lowest susceptibility to component redistribution and rheological aging. Both sulfur-containing systems exhibited high resistance to permanent deformation after RTFOT aging. The Sp-containing binder provided the lowest non-recoverable creep compliance and the highest elastic recovery, whereas Sr showed the highest phase uniformity and compositional stability. Overall, sulfur allotropy significantly influences the stabilization mechanism and performance balance of SBS-modified bitumen, with rhombic sulfur being particularly effective in suppressing phase separation.

This study investigates the efficiency of enzymatic degumming of crude soybean, rapeseed, and sunflower oils using Purifine® phospholipase C (PLC), phospholipase A1 (PLA₁), a lipase-modified component (LM), and the multienzyme complex Purifine® 3G (combining PLC, PLA₁, and LM activities), as well as their combinations. The primary objective is to achieve low residual phosphorus content (<5 ppm), which is essential for subsequent catalytic hydrotreatment in the production of hydrotreated vegetable oil (HVO) and for improving the efficiency of transesterification in the production of fatty acid methyl and ethyl esters (FAME/FAE). The degumming performance was evaluated based on the levels of phosphorus, sulfur, free fatty acids (FFA), and the dry mass of the gum phase. The highest efficiency was demonstrated by the Purifine® 3G system and the combination of PLC + PLA1 + LM, which provided deep purification, minimal loss of neutral oil, and stable FFA levels. Importantly, these enzymatic systems not only enabled residual phosphorus levels to be reduced below 5 ppm, but also significantly decreased sulfur content – from initial values of 60-100 ppm to final concentrations of 9-27 ppm, depending on the oil type. This sulfur reduction is particularly important for protecting hydrotreating catalysts and ensuring compliance with fuel standards such as EN 15940 and ASTM D975. The findings support the feasibility of enzymatic systems as a sustainable technology for the pretreatment of feedstocks for both second-generation (HVO) and first-generation (FAME) biofuel production, offering benefits in catalyst life, product purity, and process efficiency.

The influence of cationic adhesion promoters of the amine type on the properties of petroleum road bitumens is studied in the article. The impact of the selected adhesion promoters on standard quality indicators of bitumen, such as penetration, softening point, and penetration index, is evaluated. The effect of the promoters on bitumen adhesion is assessed using the bottle rolling method and the glass surface adhesion method. The thermal stability of the promoters was determined by evaluating the reduction in bitumen adhesion after short-term ageing. The influence of adhesion promoters on the bitumen contact angle is also investigated. The following set of indicators is proposed for the evaluation of the effectiveness and thermal stability of adhesion promoters.

This study examines the effect of cationic bio-based adhesion promoters (APs) derived from rapeseed oil (RO) on the performance of bitumen and asphalt mixtures. Several synthesized APs with varying polyamine content were evaluated and compared with commercial additives (Wetfix^® BE, Nouryon, Netherlands and Carbazole AK-M, SPETSKONTRAKT, Kyiv, Ukraine). Modification of bitumen with bio-based APs improved adhesion to glass and crushed stone while keeping penetration, softening point, and ductility within standard limits. Among the tested formulations, AP20 demonstrated the most balanced performance, achieving high adhesion values even at low dosages (0.2–0.4 wt. %). Asphalt concrete mixes prepared with AP20 exhibited enhanced water resistance and higher indirect tensile strength ratio (ITSR), indicating improved durability under moisture exposure. These findings highlight the potential of rapeseed oil-based adhesion promoters as effective and sustainable alternatives to conventional anti-stripping agents in road construction.

The growing emphasis on sustainable road construction has stimulated interest in environmentally friendly bitumen modifiers. This study presents the development of biodegradable adhesion promoters synthesized via the amidation of renewable raw materials (rapeseed oil and higher fatty acids) with polyethylene polyamine. The main objective was to improve bitumen–aggregate adhesion while maintaining the essential physico-mechanical and rheological properties of the bitumen. The synthesized bio-based adhesion promoters were incorporated into penetration-grade bitumen at a dosage of 0.4 wt.%. Physico-mechanical testing confirmed that their inclusion does not significantly affect the fundamental properties of the bitumen, while substantially enhancing adhesion to both glass and mineral aggregates. Rheological analysis showed that the rapeseed oil-based adhesion promoter had minimal influence on viscoelastic behavior. In contrast, the fatty acid-based promoter increased the rutting resistance parameter (|G*|/sinδ) and decreased the phase angle (δ), indicating improved resistance to permanent deformation. FTIR spectroscopy further revealed that the fatty acid-based adhesion promoter significantly reduced the formation of carbonyl groups during short-term aging, suggesting a retardation in oxidative aging and potential rejuvenating effects. In conclusion, the proposed bio-based adhesion promoters, derived from renewable sources and fully biodegradable, represent a promising solution for enhancing bitumen performance and supporting the durability and sustainability of asphalt pavements.

Restoring and strengthening existing bridges is more economically and environmentally feasible, as cement production in new RC bridges significantly contributes to CO₂ emissions. Additionally, the production of composite carbon materials for strengthening RC structures does not require a large amount of energy, unlike the production of steel for reinforcement, which requires a significant amount of electricity and, accordingly, causes a significant amount of CO₂ emissions. This is why this article presents a comprehensive review of the damage, calculations, and strengthening of RC bridge structures. It examines the main types of damage, including mechanical impacts, material fatigue, corrosion processes, seismic actions, and thermal loads. The mechanisms of their formation, correlations with environmental factors, and operational conditions are detailed. Examples of damage from real engineering objects are provided to assess the scale of the problem. Approaches to the calculation of RC bridge structures are analyzed, particularly methods for modeling the stress–strain state, considering crack formation and material degradation. Key studies by Ukrainian and foreign researchers are highlighted, identifying areas for further methodological improvement. Special attention is given to traditional and modern strengthening methods, including the use of steel elements, composites, and carbon strips. A comparative analysis of the effectiveness of different strengthening approaches is conducted. The conclusion emphasizes the need for further development of existing diagnostic, calculation, and strengthening methods. The integration of innovative materials and technologies is particularly relevant for enhancing the durability of bridges under modern operational loads.