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

Autor: Oleksii Dudin, Vladyslava Zinchenko, Olga Borziak, Oksana Krykun, Andrii Plugin
Rok vydání: 2021
Předmět:
Zdroj: Collected scientific works of Ukrainian State University of Railway Transport. :43-57
ISSN: 2413-3795
1994-7852
DOI: 10.18664/1994-7852.196.2021.241657
Popis: 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.
Databáze: OpenAIRE
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