THE USE OF NATURAL BITUMEN AS A MODIFIER OF ASPHALT CONCRETE MIXTURES

Abstract

The article presents a structured narrative literature review of modern research on the use of natural bitumen as a modifier of asphalt mixtures. The main varieties of natural bitumen used in road construction are considered, including Gilsonite, Trinidad Lake Asphalt (TLA), rock asphalt and petrobituminous rocks (oil sands). The analysis of the physico-chemical mechanisms of interaction of natural bitumen with petroleum bitumen, including the influence of asphaltenes, resinous compounds and mineral components on the rheological characteristics of binders, is carried out. Special attention is paid to the influence of natural bitumen on the resistance of asphalt concrete mixtures to rutting, water resistance, aging resistance, fatigue life, modulus of elasticity and low-temperature crack resistance. The reviewed laboratory studies generally indicate that selected natural bitumen modifiers can increase binder stiffness and high-temperature stability. Depending on the modifier type, dosage and mixture system, some studies also report improvements in rutting resistance and moisture-related performance. However, higher modifier contents may reduce low-temperature flexibility, and these laboratory trends should not be interpreted as direct evidence of long-term field durability. Based on the reviewed international evidence and the regional context of Kazakhstan, the potential applicability of natural bitumen modifiers under severe operating conditions is discussed. However, further local experimental and field validation is required before large-scale implementation. Key scientific gaps and promising areas for further research have been identified, including optimizing dosages, adapting technologies to local climatic conditions, and using domestic bitumen resources.

Special attention is paid to the influence of natural bitumen on the resistance of asphalt concrete mixtures to rutting, water resistance, aging resistance, fatigue life, modulus of elasticity and low-temperature crack resistance. It has been revealed that the use of natural bitumen can significantly increase the stiffness of the binder, reduce temperature susceptibility, improve adhesive properties and increase the resistance of coatings to plastic deformation at high operating temperatures. At the same time, it was found that an excessive increase in the content of natural bitumen can negatively affect the low-temperature characteristics of the coating, increasing the risk of thermal cracking.

Based on the analysis of international research and regional peculiarities of the road industry in Kazakhstan, the expediency of using natural bitumen as modifiers of asphalt mixtures for highways with severe operating conditions is substantiated. Key scientific gaps and promising areas for further research have been identified, including optimizing dosages, adapting technologies to local climatic conditions, and using domestic bitumen resources