The impact of the temperature and humidity state of the road on heat and mass transfer in winter

Sharp diurnal temperature fluctuations in Astana, Kazakhstan, in winter, as well as freezing up to 2 or more meters leading to the destruction of the roadway, especially during the spring thaw, prompted a detailed study of the state of roads. In this work, the temperature and humidity of the highway structure layers were monitored in winter, and the mass transfer of water in the gaseous state due to the negative pressure of cryosuction in the frozen layers was also considered. It was determined that mass transfer of water in the form of steam 1.44 10⁻⁴ g/h per 1 dm3 of soil at temperature fluctuations of -5-8 °C. The rate of vapor passage towards the freezing front in the soil was 0.467 m/h. The freezing of the ground base continued for 132 days in the winter period of 2021-2022 in Astana with the formation of 456.72 g of ice due to the migration of water in a gaseous state in every 1 m3 of soil, which increases the humidity by 40 % or more and significantly reduces the bearing road capacity during the spring thaw. As a solution to the problem of water migration in the form of steam, it is proposed to introduce an additional layer of vapour barrier over the soil base at a depth of -60 cm.Ministry of Education and Science of the Republic of Kazakhstan. Grant No. AP1326886

Поведенческие характеристики цементобетонных покрытий в Южном Казахстане: климатические изменения и оптимальный метод строительства

The present paper describes experiments and research outcomes concerning the construction of cement concrete pavements in South Kazakhstan, taking into account significant climate changes. The study has identified  potential problems in the construction of cement concrete pavements in the region, where there was no experience of their construction until  the mid-2000s. In order to develop an optimal solution, the technical factors that characterize the process of arranging these coatings using sliding molds are analyzed and quantitatively normalized. These factors include the optimal amount of mortar for curing concrete, the optimal joint cutting time, the interval and effective width of expansion joints to prevent the formation  of cracks in concrete at an early age. The effectiveness of the use of polyethylene film to prevent the formation of contraction cracks and maintain the required mode of hardening of the cement concrete pavement is shown. The main cause of damage  to the expansion joints along the length of the day coverage of coatings in the conditions of South Kazakhstan has been established. Recommendations have been developed for the installation of cement-concrete pavement and expansion joints during the construction of roads in this region. The accumulated data on climatic factors and methods of work with the use of polyethylene film have made it possible to create an optimal method for the construction of cement concrete pavements,  which will improve the quality of roads in South Kazakhstan.В статье изложены результаты исследований цементобетонных дорожных покрытий в Южном Казахстане, для которого характерны значительные изменения климата. Выявлены потенциальные проблемы устройства цементобетонных дорожных покрытий в регионе, где не было опыта их строительства вплоть до середины 2000 гг.  С целью выработки оптимального решения проанализированы и количественно нормированы технические факторы, характеризующие процесс устройства данных покрытий с использованием скользящих форм. К таким факторам  отнесены оптимальное количество раствора для отверждения бетона, оптимальное время нарезки шва, интервал и эффективная ширина деформационных швов для предотвращения образования трещин в бетоне в раннем возрасте. Показана эффективность применения полиэтиленовой пленки для предупреждения образования усадочных трещин  и поддержания требуемого режима твердения цементобетонного покрытия. Установлена основная причина повреждения швов расширения на длине дневной захватки и разработаны рекомендации по устройству цементобетонных покрытий и швов расширения при строительстве автомобильных дорог в регионе. Накопленные данные о климатических факторах и методах производства работ с использованием полиэтиленовой пленки позволят оптимизировать строительство цементобетонных дорожных покрытий в Южном Казахстане

Behavioral Characteristics of Cement Concrete Pavements in South Kazakhstan: Climatic Changes and Optimal Construction Method

The present paper describes experiments and research outcomes concerning the construction of cement concrete pavements in South Kazakhstan, taking into account significant climate changes. The study has identified potential problems in the construction of cement concrete pavements in the region, where there was no experience of their construction until the mid-2000s. In order to develop an optimal solution, the technical factors that characterize the process of arranging these coatings using sliding molds are analyzed and quantitatively normalized. These factors include the optimal amount of mortar for curing concrete, the optimal joint cutting time, the interval and effective width of expansion joints to prevent the formation of cracks in concrete at an early age. The effectiveness of the use of polyethylene film to prevent the formation of contraction cracks and maintain the required mode of hardening of the cement concrete pavement is shown. The main cause of damage to the expansion joints along the length of the day coverage of coatings in the conditions of South Kazakhstan has been established. Recommendations have been developed for the installation of cement-concrete pavement and expansion joints during the construction of roads in this region. The accumulated data on climatic factors and methods of work with the use of polyethylene film have made it possible to create an optimal method for the construction of cement concrete pavements, which will improve the quality of roads in South Kazakhstan