Open AccessUltrafast transfer strength of reinforced concrete sleepers by Using complex additives
Author(s) -
Andrii Plugin,
Olena Kaliuzhna,
Olga Borziak,
Олексій Андрійович Плугін,
Oleksandr Savchenko
Publication year - 2021
Publication title -
zbìrnik naukovih pracʹ ukraïnsʹkoï deržavnoï akademìï zalìzničnogo transportu/zbìrnik naukovih pracʹ
Language(s) - English
Resource type - Journals
eISSN - 2413-3795
pISSN - 1994-7852
DOI - 10.18664/1994-7852.197.2021.248243
Subject(s) - cement , superplasticizer , hardening (computing) , materials science , composite material , crystallization , dispersion (optics) , compressive strength , chemical engineering , physics , optics , layer (electronics) , engineering
The influence of superplasticizers-polycarboxylates and their complex additives withaccelerants - electrolytes and dispersion of calcium hydroxylates on the early strength of concretefor concrete of concrete sleepers has been studied. It was found that the use of superplasticizerspolycarboxylates can improve the early strength of the concrete after heat treatment, but eachadditive must be checked for consistency with the cement used. Approx Complex additives withaccelerators in conditions of natural hardening ensure an increase in the early strength of concrete,but some of them, which accelerate natural hardening, can reduce the strength after WWTP and mustbe checked before use. Electron-microscopic examinations of the structure of cement stone withadditives were carried out and it was found that the additive of only policarboxylate does not changethe structure of hydration products. Complex additives lead to formation of additional number ofcrystalline hydrates of AFm- and/or AFt-phases. The scheme of development of the cement hardeningprocess and the initial stage of cement hardening without or with additives has been developed. Bymeans of which the highest accelerating effect of the complex addition of polycarboxylate andcalcium hydroxylate dispersions was established by experimental investigations, Dispersion particlesincrease surface area where crystallization (condensation) of cement hydration products takes placeand ensures faster filling of spaces between cement particles (mineral additives) with them, fillers)with establishment of lances with electro-heterogeneous contacts. As a result of potentiodynamic andmicroscopic investigations it was established that the tested additives in the dosages do not causecorrosion effect on the steel reinforcement bars. Transmission strength values of 32 MPa for sleepersafter 24 years of hardening under low-heat regime and after 2 days of natural hardening have beenachieved. The formula for economic efficiency of using additives to reduce the energy intensity ofproduction of concrete sleepers has been proposed.