The article presents the results of determining the strength of non-destructive methods of cement concrete pavement on bridges. According to the results of the research, a differential curve, a reliability curve and the inverse value of the accumulated frequency of compressive strength of cement concrete are constructed. It is established that the cement concrete of the investigated objects corresponds to the strength class according to the normative documents. However, the results of visual, instrumental and thermal imaging inspection of areas on the bridges revealed a number of defects in the cement-concrete pavement and pavement slabs, which can lead to loss of the pavement structure strength. In particular, it was found that the destruction of the inspected reinforced concrete slabs of bridges mainly occurs under the influence of corrosion and loss of the working part volume of the steel reinforcement, unsatisfactory condition of the compensation seams on the supports. It is determined that cracks in reinforced concrete slabs occur due to low resistance of concrete to bending loads, due to which steel reinforcement is exposed to aggressive environments. In turn, it was proved that structural cracks in concrete occurred due to excessive loading, which led to overstrain of the structure, and non-structural cracks - due to internal stresses caused by thermal loads and various linear expansions of materials. Thermal imaging study revealed a significant difference in temperature in the pavement structural elements, which in the future leads to the destruction of cement-concrete pavement. It was found that the peeling of the protective layer of metal reinforcement on the studied bridges is caused by the phenomenon of electro-chemical corrosion. The experience analysis of cement-concrete pavement of the studied objects allows to prepare proposals for the construction of cement-concrete pavement of bridges and overpasses using modern materials, in particular, non-metallic reinforcement.

No abstract

Modern construction standards require the design and construction of roads for loading, compatible with European standards - 11.5 tons per axle, which corresponds to the actual total weight of the vehicle 34 tons with the maximum number of axles (6 axles). Only 25% of state roads meet these normative loads (according to Ukravtodor on Facebook) [1-6] .There are examples when modern heavy goods vehicles (these are heavy construction dump trucks and so-called lorries) significantly exceed the standard load per axle (11.5 tons per axle). This significantly increases the destructive impact and reduces the standard service life of the road. Road traffic regulations in Ukraine prohibit the movement of vehicles with an actual weight of more than 40 tons on roads of national importance. An exception is made for container trucks - the weight limit is 44 tons. On local roads, built mainly for the loading of 6 tons per axle, the movement of vehicles with axle loading over 7 tons or the actual weight of over 24 tons is prohibited. Unfortunately, however, in Ukraine there is a massive violation of these standards. This problem has become even more acute with the change of logistic chains of transportation as a result of the military aggression of Moscow after February 24, 2022. There is no technology or coating in the world capable of withstanding a constant load of 80-120 tons. Even a slight overload (by 1-2 tons) entails the destruction of the road at times. Maximum loaded vehicle, regardless of the number of axles, has a destructive effect on the pavement more than the normative from 2 to 56 times. The paper considers the brands of specific vehicles, most frequently moving on the roads of Ukraine with the specification of the following parameters of loads from the wheels of modern vehicles, namely, the distance between the axles, tire pressure, area and shape of the wheel imprint, depending on the load of the vehicle with subsequent use of the data to calculate the pavement structures.

The method of sealing materials effectiveness evaluation in the repair of bituminous-concrete surface with transversal cracksis offered. Calculation schemes and mathematical models based on the application of the thermo-viscous-elasticity theory forthe prediction of temperature stresses in the sealing material at the contact with the bituminous-concrete surface, taking intoaccount the thermal-technical and thermorheological properties of the materials and the geometric parameters of the bituminous-concreteslabs and the transversal crack. The obtained analytical dependences allow to estimate the service life beforethe loss of sealant compound integrity or adhesive strength of their adhesion with bituminous-concrete surface taking intoaccount annual and daily temperature fluctuations according to the main provisions of the kinetic theory of solid bodiesstrength.

Поставлена задача про чисельне дослідження термопружного деформування шаруватого покриття дороги на її вгнутих та прямолінійних ділянках. Сформульовані розв'язні рівняння, побудовані їх скінченно-елементні аналоги. Розглянуто випадки навантажень при різних значеннях геометричних, конструктивних та температурних параметрів. Проаналізовано вплив викривлення на перерозподіл полів напружень при дії температурних збурень. Оскільки при рівномірному нагріванні (охолодженні) криволінійні шари подовжуються по-різному, то можна зробити висновок, що навіть при найменшій кривизні дороги проявляються властивості концентрації всіх напружень в зонах, які прилягають до кінців дороги. Причому, для прямолінійних доріг нормальні до поверхні контакту напруження практично рівні нулю. При збільшені кривизни спостерігається збільшення значення нормального розтягуючого напруження по всій довжині дороги, що може привести тим самим до великої ймовірності відриву першого шару від другого. Чисельними дослідженнями показано, що пікові значення поздовжніх напружень розтягу у верхньому шарі покриття і зсувних напружень, локалізованих між першим і другим шарами, можуть бути причиною спостережуваних на практиці утворення на дорозі на початковій стадії руйнування та подальшого перетворення їх на поперечні тріщини. Ключові слова: Автомобільна дорога, дорожне покриття, транспортні навантаження, термопружений ста, поле напружень.