scholarly journals INFLUENCE OF CONCRETE CORROSION FROM THE INTERACTION OF ALKALIS OF CEMENT WITH REACTIVE AGGREGATES ON DAMAGE TO REINFORCED CONCRETE SLEEPERS IN A TRACK

2021 ◽  
pp. 43-57
Author(s):  
Andrii Plugin ◽  
Oksana Krykun ◽  
Vladyslava Zinchenko ◽  
Olga Borziak ◽  
Oleksii Dudin
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Operating Conditions ◽  
Northern Europe ◽  
Alkali Silica Reaction ◽  
Limited Extent ◽  
Concrete Corrosion ◽  
Road Surfaces ◽  
Water Cut ◽  
Longitudinal Cracks

The article analyses the causes of cracks and other damage in reinforced concretesleepers. The effect of concrete corrosion, which is caused by the interaction of cement alkalis withreactive aggregates, on damage to sleepers has been established. The significance of each of thereasons has been established. Corrosion of concrete sleepers, which is caused by the reactionbetween alkalis and silicic acid - Alkali-Silica Reaction (ASR), in Ukraine was initially caused by ahaphazard change in suppliers of aggregates and cement. Also it influenced by the modernization ofthe production of cement plants, which led to an increase in the content of alkalis in cement by morethan 0.6%. Of all concrete structures, corrosion from ASR proceeds faster precisely in the railwaytrack structures - its signs appear on average after 2.8 years of operation, and the foundations ofoverhead catenaries - after 3 years. For other structures, these signs appear later - for bridgestructures after 3.7 years, for road surfaces - after 6.9 years. This is due to the peculiarities of thedesign and operating conditions of the sleepers, including, possibly, the effect of leakage currentsadditional to the water cut. The corrosion rate from ASR in structures in Ukraine is much higher(signs of corrosion appear on average after 2.2 years) than in the countries of North America, Central and Northern Europe (6.1 and 6.4 years, respectively). This is due to the wider use of additives inconcrete, a better regulatory framework and a culture of compliance in these countries. ASR directlycauses 15.5 % of defects, contributes to the formation and development of 32.8% of defects to thegreatest extent, does not affect 30.9 % of defects at all, and to a limited extent contributes to theemergence and development of other 20.8 % of defects. The effect of corrosion of concrete from ASRon the occurrence of damage (defects) in sleepers is explained by the fact that as a result of ASRtensile stresses arise in concrete, which lead to the formation of a spatial network of microcracks anda decrease in the tensile strength of concrete. Since the prestressing of the reinforcement has createdtensile stresses in the transverse direction, predominantly longitudinal cracks occur in the sleepers.Prestressed reinforced concrete structures are more vulnerable to damage caused by ASR concretecorrosion than conventional reinforced concrete or concrete structures.

Effect of the ITZ Damage on Durability of Reinforced Concrete in Chloride Environment

1994 ◽  
Vol 370 ◽  
Author(s):  
Raoul François ◽  
Ginette Arliguie
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Concrete Structures ◽  
Operating Conditions ◽  
Reinforced Concrete Structures ◽  
Actual Operating ◽  
Chloride Environment ◽  
Concrete Elements ◽  
Transfer Properties ◽  
Salt Fog

AbstractThis paper deals with the effect of the ITZ on the service life of reinforced concrete. In the case of reinforced concrete structures, the penetration of chlorides does not depend only on concrete transfer properties but also on the loading applied, on the state of strains and on the exposure to the aggressive environment.In order to take into account these different parameters, we have performed experiments on reinforced concrete elements, over a long period. The samples used have to be of an adequate size (3 meters long) and stored in a salt fog in a loading state so as to be representative of the actual operating conditions of the reinforced concrete structures.The bending of the beams leads to the development of cracks which are neither preceded nor accompanied by microcracks, but the cement paste-aggregate interfaces are damaged in the tensile areas.The service loading of reinforced concrete has two consequences : firstly, a cracking with widths ranging between 0.05 mm and 0.5 mm according to the intensity of the mechanical strength applied. Secondly, a damage of the ITZ in the tensile areas causing an increase of chloride penetration directly proportional to the intensity of the stress applied to the beam.The model of the development of corrosion, worked out in relation with time and based on our results, emphasizes the influence of the paste-aggregate interface damage on the duration of the service life.

scholarly journals Thermal Performance of Alginate Concrete Reinforced with Basalt Fiber

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 779
Author(s):  
Seyed Esmaeil Mohammadyan-Yasouj ◽  
Hossein Abbastabar Ahangar ◽  
Narges Ahevani Oskoei ◽  
Hoofar Shokravi ◽  
Seyed Saeid Rahimian Koloor ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Thermal Performance ◽  
Concrete Structures ◽  
Basalt Fiber ◽  
Operating Conditions ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Structures ◽  
Anionic Polymer ◽  
Temperature Range

The sustainability of reinforced concrete structures is of high importance for practitioners and researchers, particularly in harsh environments and under extreme operating conditions. Buildings and tunnels are of the places that most of the fire cases take place. The use of fiber in concrete composite acts as crack arrestors to resist the development of cracks and enhance the performance of reinforced concrete structures subjected to elevated temperature. Basalt fiber is a low-carbon footprint green product obtained from the raw material of basalt which is created by the solidification of lava. It is a sustainable fiber choice for reinforcing concrete composite due to the less consumed energy in the production phase and not using chemical additives in their production. On the other hand, alginate is a natural anionic polymer acquired from cell walls of brown seaweed that can enhance the properties of composites due to its advantage as a hydrophilic gelling material. This paper investigates the thermal performance of alginate concrete reinforced with basalt fiber. For that purpose, an extensive literature review was carried out then two experimental phases for mix design and to investigate the compressive strength of samples at a temperature range of 100–180 °C were conducted. The results show that the addition of basalt fiber (BF) and/or alginate may slightly decrease the compressive strength compared to the control concrete under room temperature, but it leads to control decreasing compressive strength during exposure to a high temperature range of 100–180 °C. Moreover, it can be seen that temperature raise influences the rate of strength growth in alginate basalt fiber reinforced concrete.

scholarly journals Life prediction for spillway facility side wall

2019 ◽  
Vol 97 ◽  
pp. 04041 ◽  
Author(s):  
Asror Yangiev ◽  
Anvar Ashrabov ◽  
Oybek Muratov
Keyword(s):  
Reinforced Concrete ◽  
Life Prediction ◽  
Concrete Structures ◽  
Side Wall ◽  
Structural Features ◽  
Operating Conditions ◽  
Reinforced Concrete Structures ◽  
Remaining Life ◽  
Safe Operation ◽  
Analytical Assessment

This article includes the analytical assessment of the durability and remaining life of the I-st category reinforced concrete structures by the fracture mechanics approaches, the prediction is based on the consideration of temporal changes in the structural features of a particular type of concrete. The main purpose of this work is to determine the durability of reinforced concrete structures and the remaining life of the spillway and components in the implemented modes and operating conditions that ensure their safe operation and environmental protection. When predicting the durability of the spillway reinforced concrete structures, each structure is considered as a component of the structure behavior scheme. The result of the durability predictions is presented in years, which can eventually determine the remaining life of the structural component of spillway.

Design of precast reinforced concrete structures of frame buildings: a new set of rules

2019 ◽  
pp. 4-9 ◽  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Building Frames ◽  
Fine Grained ◽  
Rigid Frame ◽  
Floor Slabs ◽  
Frame Buildings ◽  
Spatial System ◽  
Precast Elements

Currently, prefabricated reinforced concrete structures are widely used for the construction of buildings of various functional purposes. In this regard, has been developed SP 356.1325800.2017 "Frame Reinforced Concrete Prefabricated Structures of Multi-Storey Buildings. Design Rules", which establishes requirements for the calculation and design of precast reinforced concrete structures of frame buildings of heavy, fine-grained and lightweight structural concrete for buildings with a height of not more than 75 m. The structure of the set of rules consists of eight sections and one annex. The document reviewed covers the design of multi-story framed beam structural systems, the elements of which are connected in a spatial system with rigid (partially compliant) or hinged joints and concreting of the joints between the surfaces of the abutting precast elements. The classification of structural schemes of building frames, which according to the method of accommodation of horizontal loads are divided into bracing, rigid frame bracing and framework, is presented. The list of structural elements, such as foundations, columns, crossbars, ribbed and hollow floor slabs and coatings, stiffness elements and external enclosing structures is given; detailed instructions for their design are provided. The scope of the developed set of rules includes all natural and climatic zones of the Russian Federation, except seismic areas with 7 or more points, as well as permafrost zones.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Sign in / Sign up

Export Citation Format

Share Document