This paper reports a study of the cement-concrete coating on bridges using FRP reinforcement. That has made it possible to design optimal structures by selecting the height for reinforcement arrangement in the layers of a roadbed in order to ensure strength characteristics. An engineering method for calculating a hard roadbed with composite reinforcement has been devised, which makes it possible to take into consideration its work both in a joint package of the structure with a slab and separately – when it exfoliates from the slab of the bridge's span structure. Underlying this research are effort-determining methods, estimation dependences from the theory of bending layered structures, as well as dependences from elasticity theory to assess the strength of materials for a roadbed. The consideration of shear strains when designing slabs has helped establish that the deflections according to the devises method were 1.4 times larger than those in the classical approach. The method was tested by a numerical experiment, which confirmed the need to use composite reinforcement in the upper layers of a road surface on bridges, which improves its durability by 1.2 times. The results of the numerical experiment indicate that the equivalent stresses in the lower layers of a free-moving roadbed were 2.91 MPa, and, when operating in a joint assembly with a slab, they took a negative value (–0.2 MPa). Practical application of the devised calculation method makes it possible to determine the refined normal stresses in the layers of a roadbed, taking into consideration the characteristics of structure operation. Owing to this, additional opportunities open up for calculating the roadbeds of bridges whose design utilizes the most common types of span structures in the bridge industry.
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.
The article is devoted to the selection of the composition of the cement-concrete mixture and the determination of physical and mechanical parameters of the draining cement concrete for the arrangement of the pavement of footpaths, parking lots and hydraulic structures with high drainage capacity. The object of research is the processes of composition design and ensuring the strength and capacity of draining cement concrete. The aim of the work is to select the composition and determine the physical and mechanical (compressive strength, tensile bending, deformable (modulus of elasticity), operational (abrasion), frost resistance, water permeability of draining cement concrete. Research methods - scientific and experimental. The results of the article can be used in the operation of road and airfield pavements in the culverts and foundations to improve the environmental friendliness of cities.
The work presents a study of the destructive impact of modern overloaded vehicles on the construction of non-rigid road clothing. According to the results of the analysis, the dependence of the influence of overloaded vehicles (according to the manufacturer's plant) on the change in the parameters of non-rigid road clothing (thickness of the layer of asphalt concrete layers, general modulus of elasticity, service life) was established.
Abstract. The article is devoted to quality control of cement-concrete road surfaces at large construction facilities. Purpose of work. Improvement the methods of calculating the characteristic and design values of the cement concrete strength. The object of research is the cement concrete pavement. Research method: experimental scientific-research. The article provides: the quality control process in the construction of cement-concrete pavement and bottom, statistical processing of experimental values compressive and tensile strength, comparative characteristics in normative documents and the main changes between them are performed, also analysis of the European standard is carried out. The values of the tolerance limit t for calculating the characteristics and design values of strength are given, for the number of tests n = 25 with different reliability index for transport structures and distribution laws. The calculation and comparison of the characteristic and calculated design values of the cement concrete strength in accordance with the national standard and the European one is carried out. The results can be used in the calculation of the characteristic and design values of the cement concrete strength during design of concrete mixes.
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