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TECHNICAL SCIENCES
PROSPECTIVE DIRECTIONS OF CONSTRUCTION OF ROADS
WITH CEMENT CONCRETE COVERING 1 2 Salimova B.D. , Hudaykulov R.M. (Republic of Uzbekistan)
Email: Salimova574@scientifictext.ru
1Salimova Barno Djamalovna - Candidate of Technical Sciences, Associate Professor; 2Hudaykulov Rashidbek Mansurzhonovich - PhD in Engineering, Associate Professor, EXPLORATION AND AUTOMOBILE ROAD DESIGNING DEPARTMENT, TASHKENT STATE TRANSPORT UNIVERSITY, TASHKENT, REPUBLIC OF UZBEKISTAN
Abstract: the article discusses promising road construction technologies used for the arrangement of road pavements. The characteristic differences of cement concrete from asphalt concrete, which are manifested in the construction and operation of highways from these materials, are considered. The advantages of draining (large-porous) concrete are noted. The influence of various additives used in Russia and in Western countries is considered. The conclusion is made about the prospects of using innovative materials and technologies in road construction. Keywords: cement-concrete road surface, cement-concrete mixtures, road construction.
ПЕРСПЕКТИВНЫЕ НАПРАВЛЕНИЯ СТРОИТЕЛЬСТВА АВТОМОБИЛЬНЫХ ДОРОГ С ЦЕМЕНТОБЕТОННЫМ
ПОКРЫТИЕМ 12 Салимова Б.Д. , Худайкулов Р.М. (Республика Узбекистан)
1Салимова Барно Джамаловна - кандидат технических наук, доцент;
2Худайкулов Рашидбек Мансуржонович - доктор философии в области технических наук, доцент, кафедра изысканий и проектирования автомобильных дорог, Ташкентский государственный транспортный университет, г. Ташкент, Республика Узбекистан
Аннотация: в статье рассматриваются перспективные дорожно-строительные технологии, используемые для обустройства дорожной одежды. Рассмотрены характерные отличия цементобетона от асфальтобетона, проявляющиеся в строительстве и эксплуатации автомобильных дорог из этих материалов. Отмечены достоинства дренирующего (крупнопористого) бетона. Рассмотрено влияние различных добавок, используемых в России и в западных странах. Сделан вывод о перспективах использования инновационных материалов и технологий в дорожном строительстве. Ключевые слова: цементобетонное дорожное покрытие, цементобетонные смеси, строительство автомобильных дорог.
The dynamic development of road transport and the volume of cargo transportation determine the need for constant development of the road network, improving the road surface. The unsatisfactory condition of motorways leads to a decrease in the speed of movement, increased wear of parts and assemblies of cars, more frequent repairs of vehicles, an increase in fuel consumption and an increase in the number of road accidents.
Today, all road construction technologies for the arrangement of pavements are based on the use of two alternative materials: asphalt concrete and cement concrete. All theoretical calculations and practical studies indicate that no matter in what weather and climatic conditions, at what traffic intensity and what kind of traffic flow the road is used, the cement concrete pavement lasts much longer. The overhaul life for rigid cement-concrete clothes is significantly higher than this parameter for non-rigid coatings and is
25 years [1]. Taking into account these characteristics, the use of cement concrete in the construction of highways seems reasonable.
When using cement concrete in the road construction industry in Uzbekistan, local specifics must be taken into account. The characteristics of the concrete pavement are determined by the composition of the concrete mixture used. Properties such as flexural tensile strength and frost resistance are of particular importance. In the mountainous regions of the country, these properties play a key role.
Good frost resistance of concrete is provided, on the one hand, by the appropriate aggregates added to it, and on the other hand, by a reduced water-cement ratio and air entrainment into the concrete mixture. A reduced water-to-cement ratio requires an even distribution of cement throughout the entire volume of concrete and provision of conditions for cement hydration. This is achieved through the addition of plasticizing additives.
The long service life of the cement concrete pavement is influenced by the physical and chemical properties of the cement concrete. The strength and tendency to deformation of cement concrete remain practically unchanged with changes in temperature and humidity, which cannot be said about asphalt concrete. The cement-concrete bed is characterized by an increase in strength during operation (by about 10-20%), despite the constant loads from transport and the impact of natural factors. As a result, on modern cement-concrete highways, the formation of a track, which invariably appears on the asphalt-concrete surface, is excluded [2].
Today, it is possible to give certain properties to concrete or change its characteristics chemically -by adding various components to the mixture. Concrete used for the construction of highways must necessarily contain air-entraining and plasticizing additives. Thanks to the active use of innovative additives, it is possible to improve the characteristics of concrete so that it meets the most stringent modern requirements [3].
The development of modern technologies in the field of concrete production for road works goes towards increasing the strength and durability of the finished pavement. The solution to this problem becomes possible due to the inclusion of three types of additives in the composition of the concrete mixture: air-entraining, plasticizing and gas-forming. Russian specialists managed to obtain good results by using a complex chemical additive, including superplasticizer C-3 and air-entraining additive SNV. In Western countries, a complex additive is actively used, in which plasticizing, air-entraining and gas-forming actions are combined. The practical application of cement-concrete pavements shows that the use of high-grade concrete allows one to reduce the thickness of a single-layer concrete pavement by about a third compared to a sheet made on the basis of B3.5 class concrete. This makes single-layer high-grade concrete coatings preferable both in terms of technology and economics.
Of particular interest is the use of drainage (coarse-porous) concrete in road construction. Careful selection of the composition using the necessary chemical and mineral additives makes it possible to obtain high-strength concrete that can withstand a load of 30 MPa. It is effective to use such a material as an upper or intermediate layer of a multilayer structure. Thanks to this, it is possible to avoid the effect of aquaplaning and the accumulation of moisture at the base of the roadway, which significantly extends the service life of the pavement.
Thus, it can be argued that the use of innovative materials and technologies in road construction is a priority. This makes it possible to develop the road network at a high rate at lower financial costs.
References / Список литературы
1. Salimova B.D., Khudaykulov R.M. Cementobetonnye smesi v stroitel'stve avtomobil'nyh dorog // Vestnik nauki i obrazovaniya, 2020. № 3-3 (81).
2. Pugin K.G., Yushkov V.S. Ispol'zovanie vtorichnyh materialov dlya cementobetonnyh pokrytij. Vestnik Permskogo nacional'nogo issledovatel'skogo politekhnicheskogo universiteta. Ohrana okruzhayushchej sredy, transport, bezopasnost' zhiznedeyatel'nosti, 2013. № 1. S. 144-151.
3. Yakobson M.Ya. еt al. Aktual'nost' i perspektivy primeneniya cementobetona v dorozhnom stroitel'stve. Sistemnye tekhnologii, 2016. № 18.
