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Open AccessArticle

Diagnostics of Concrete and Steel in Elements of an Historic Reinforced Concrete Structure

by Paweł Tworzewski, Wioletta Raczkiewicz, Przemysław Czapik and Justyna Tworzewska

Materials 2021, 14(2), 306; https://doi.org/10.3390/ma14020306 - 8 Jan 2021

Cited by 13 | Viewed by 4037

Existing buildings, especially historical buildings, require periodic or situational diagnostic tests. If a building is in use, advanced non-destructive or semi-destructive methods should be used. In the diagnosis of reinforced concrete structures, tests allowing to assess the condition of the reinforcement and concrete cover are particularly important. The article presents non-destructive and semi-destructive research methods that are used for such tests, as well as the results of tests performed for selected elements of a historic water tower structure. The assessment of the corrosion risk of the reinforcement was carried out with the use of a semi-destructive galvanostatic pulse method. The protective properties of the concrete cover were checked by the carbonation test and the phase analysis of the concrete. X-ray diffractometry and thermal analysis methods were used for this. In order to determine the position of the reinforcement and to estimate the concrete cover thickness distribution, a ferromagnetic detection system was used. The comprehensive application of several test methods allowed mutual verification of the results and the drawing of reliable conclusions. The results indicated a very poor state of the reinforcement, loss in the depth of cover and sulphate corrosion. Full article

(This article belongs to the Special Issue Testing of Materials and Elements in Civil Engineering)

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12 pages, 1949 KB

Open AccessArticle

Manufacturing Errors of Concrete Cover as a Reason of Reinforcement Corrosion in a Precast Element—Case Study

by Kamil Bacharz, Wioletta Raczkiewicz, Magdalena Bacharz and Wioletta Grzmil

Coatings 2019, 9(11), 702; https://doi.org/10.3390/coatings9110702 - 27 Oct 2019

Cited by 23 | Viewed by 4102

Abstract

The article concerns the assessment of technical condition of the precast loggia wall in a large panel building after 25 years of use as well as the cause of its damage. As a result of the study, cracks and losses of the concrete cover were found. Corrosion products were visible on exposed reinforcing rods. The reinforcement distribution and concrete cover thickness in loggia wall were estimated using a rebar detector. The corrosion assessment of reinforcement was performed using a semi non-destructive galvanostatic pulse method that allows the location of areas of corrosion and estimate the reinforcement corrosion activity. The phase composition of the concrete cover was analyzed. The test results showed an insufficient thickness of the concrete cover as the main cause of loggia wall damage. The research indicated that manufacturing errors made in the prefabrication plants affect the technical condition of precast elements and may lead to the damage of the structure well before the expected of its service life. In the case of manufacturing errors causing the implementation of an element with a concrete cover that does not meet the standard requirements for thickness and tightness, it is recommended to use protective coatings to increase the element’s durability to the designed level. Full article

(This article belongs to the Special Issue Manufacturing and Surface Engineering II)

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15 pages, 4123 KB

Open AccessArticle

Electrochemical Diagnostics of Sprayed Fiber-Reinforced Concrete Corrosion

by Wioletta Raczkiewicz and Paweł Grzegorz Kossakowski

Appl. Sci. 2019, 9(18), 3763; https://doi.org/10.3390/app9183763 - 9 Sep 2019

Cited by 10 | Viewed by 4480

Abstract

Sprayed fiber-reinforced concrete is used in construction for the execution and repair of reinforced concrete elements. It is believed that the addition of steel fibers is most effective, due to their parameters and low costs. Some researchers, however, suggest that the addition of steel fibers can contribute to the initiation of corrosion of the main reinforcement. In consideration of the differences of opinion on the corrosion resistance of sprayed fiber-reinforced concrete, it has become necessary to analyze this issue. The article presents comparative studies of corrosion assessments of the main reinforcement in specimens made of ordinary concrete and concrete with steel fibers. The tests were performed using a semi non-destructive galvanostatic pulse method, which allows location of the areas of corrosion and estimation of the reinforcement corrosion activity. In order to initiate the corrosion processes the specimens were subjected to freezing cycles in NaCl solution. In addition, the shrinkage and compressive strength of specimens were measured, and the observation of specimen structure under a scanning microscope was performed. It was found that galvanostatic pulse method allowed estimation of the reinforcement corrosion progress. The corrosion of the main reinforcement in steel fiber reinforced concrete specimens was less advanced than in the specimens without fibers. Full article

(This article belongs to the Special Issue Fiber-Reinforced Concrete)

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