Introduction. The article examines the U.S. experience regarding the use of frost-resistant admixtures in reinforced concrete structures of transport facilities. Technologies for increasing concrete durability under cyclic freezing and thawing conditions are analyzed, with examples of applications in bridges in the states of Minnesota, Michigan, and Alaska. The results of studies on the effectiveness of various types of admixtures and their impact on the performance characteristics of structures are presented. Opportunities for adapting the American experience in Ukraine are identified.
Problem Statement. The main problem with reinforced concrete structures of transport facilities in cold regions is their insufficient resistance to freeze-thaw cycles. Water penetrating the concrete pores expands during freezing and creates internal stresses, leading to cracking, surface scaling, and gradual loss of strength. In the U.S., this issue is particularly relevant for bridges and road pavements in northern states, where the number of freeze-thaw cycles can exceed one hundred per year. The solution to this problem lies in the use of frost-resistant admixtures that reduce concrete permeability and increase its durability.
Materials and Methods. To increase the frost resistance of concrete, American engineers use various types of admixtures: air-entraining agents that form micropores; mineral admixtures (fly ash, ground granulated blast-furnace slag, silica fume) that densify the structure of the cement paste; and modern nano-modified materials. Research methods include laboratory testing for freeze-thaw cycles, measuring concrete permeability, microstructure analysis, and long-term operational observations of actual transport structures.
Results. Studies have shown that the use of air-entraining admixtures ensures concrete frost resistance at a level of 300–400 freeze-thaw cycles. The use of silica fume allows for a reduction in concrete permeability by 40–45%, significantly decreasing the risk of cracking. Composite admixtures (a combination of air-entraining agents with slag materials) demonstrate the highest efficiency — up to 500 cycles without loss of strength. Practical examples of bridges in Minnesota, Michigan, and Alaska confirm that such technologies extend the service life of structures by decades.
Conclusions. The American experience proves that the use of frost-resistant admixtures is a key factor in ensuring the durability of transport structures in cold climates. The use of various types of admixtures allows for the adaptation of concrete mixes to specific operating conditions, reduces repair costs, and increases infrastructure reliability. For Ukraine, the implementation of similar technologies is relevant, taking into account local resources (fly ash, slag) and the improvement of the regulatory framework for controlling concrete frost resistance.
