opk Current issue
Department of Building Structures, Silesian University of Technology, Gliwice, Poland
This paper refers to the evaluation of the effectiveness of electrochemical chloride extraction from concrete. The naturally slow process of chloride ingress into concrete cover was accelerated by chloride migration in the electric field. Later we performed the process of electrochemical chloride extraction. The process mechanism of reinforcement corrosion was tested by EIS during the process of chloride ingress into concrete, before and after the extraction process. After completing impedance measurements, concrete cover ground in layers was used to prepare model solutions of concrete pore water, in which chloride concentration and pH values were determined. The total analysis of impedance measurements of steel reinforcement, chloride and pH profiles in concrete was used to evaluate the effectiveness of electrochemical extraction. That treatment greatly reduced chloride concentration in concrete, but not always decreased corrosion rate of reinforcement.
Keywords: concrete structures, reinforcing steel, chlorides, concrete repair, electrochemical chloride extraction, ECE, impedance measurements, EIS.
Vol. 61, nr 1, s. 3-9
Politechnika Krakowska im. T. Kościuszki, Kraków
Instytut Badawczy Dróg i Mostów, Warszawa
Because of the increasing production of concrete in the world, there is a problem related to the unused concrete mix utilization. The use of two component powder admixture, causing binding and granulating the unused fresh concrete mix is described in the paper. The granules obtained in this way may be used as a substitute of the part of natural aggregate in newly produced concrete mixes. The aim of the tests was to determine the effect of added granules amount on selected properties such as: consistency and air content of fresh concrete and compressive strength of concrete.
Keywords: recycled aggregate, unused fresh concrete, concrete properties, compressive strength, consistence
Vol. 61, nr 1, s. 10-13
Faculty of Civil Engineering, Silesian University of Technology, Gliwice
Institute of Ceramics and Building Materials, Department of Refractory Materials, Gliwice
On the renovated brick façades of the adapted post-industrial building of the power plant, strong salt efflorescence appeared in the fugues and on facing bricks. In order to clarify the causes of efflorescence, brick samples were tested physically, chemically, phase and microstructurally. Analyzes of strength tests showed that the values of new brick (3 years) parameters were worse in comparison to old bricks (100 years). The new bricks were susceptible to loosening the top layers – unsalted ones were characterized by numerous micro cracks, and the salted microstructure with loose incoherent matrix forms. Chemical analyzes and phase composition of the tested bricks and efflorescence revealed the presence of alkaline sulphates, gypsum and carbonates. Aggressive ions likely to come from the external environment, as well as the materials used during the renovation of the facade also involving the cleaning and replacement of damaged bricks and fugues.
Keywords: facing brick, salt efflorescence, SEM, XRD
Vol. 61, nr 1, s. 14-18
CORROSION PROTECTION IN PRACTICE
Diagnostyka i Naprawy Konstrukcji, Warszawa
Ways to repair reinforced concrete bridge structures damaged as a result of chloride corrosion of reinforcement are discussed. The most common causes of failure of repair are specified. Recommendations to avoid failures of repair are given.
Part 1 concerns overpass 11T on Marymoncka – Słowackiego Streets over Line T in Warsaw. Part 2 concerns Estakada 26T in Modlińska junction, leading to Jagiellońska Street to the Stefan Grot-Rowecki Bridge in Warsaw.
Keywords: concrete bridges, chloride corrosion, reinforcement corrosion,
protection against corrosion of reinforcement, concrete repair
Vol. 61, nr 1, s. 19-23
Doradca techniczny NOXAN
Mimo powszechnego używania betonu jako materiału budulcowego nadal pojawiają się problemy na etapie jego odpowiedniego zabezpieczenia przez niszczeniem czy uzupełniania pojawiających się ubytków. Nie ma lepszej ochrony przed korozją niż dobrze dobrana farba na beton o najwyższej jakości i o parametrach najlepiej odpowiadających danej inwestycji, zaaplikowana na podłoże po dokładnie wykonanych pracach przygotowujących do użytkowania.
Vol. 61, nr 1, s. 24-25