AdMaS KCE - Stavební zkušebnictví

Browse

Recent Submissions

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Study of a different carbonation intensity on the internal surface of cracks and inside concretes with dense aggregate and concrete recyclate
    (IOP Publishing, 2018-07-16) Stehlík, Michal; Knapová, Jana; Mácová, Petra
    The paper focuses on the experimental physical-chemical analysis of different carbonation intensity by TG/DTG and FTIR method on the selected surfaces of concretes with aggregate and with concrete recyclate, with and without polymer and steel fibres.
  • Thumbnail Image
    Item
    Permeation and diffusion tests for estimation of durability of fibreconcretes with dense aggregate and recycled concrete
    (IOP Publishing, 2018-07-16) Stehlík, Michal; Knapová, Jana; Heřmánková, Věra
    Mechanical and deformational properties of concrete are markedly improved by the addition of long structural fibres. This addition, however, not always improves the durability of concrete. One important factor for an estimation of concrete durability is to assess the permeation and diffusion characteristics of the surface layer. The research was performed by means of the TORRENT permeability method and the method for determination of the nonsteady-state migration coefficient of chlorides in concrete – NORDTEST. The addition of long polypropylene fibres contributes to increasing the permeability of the surface layer for air and chloride solution, but no too significantly. The higher permeability was determined in concrete with concrete recyclate and polypropylene fibres. The measured results by both used methods are partially comparable and can be used for raw estimation of durability of concretes. The higher values of permeability indicate the expected lower durability of tested concretes.
  • Thumbnail Image
    Item
    Experimental determination of the initial compressive strength of concrete using a rebound test hammer
    (IOP Publishing, 2018-07-16) Cikrle, Petr; Kocáb, Dalibor; Misák, Petr
    This paper deals with rebound hammer testing of concrete in the early stage of ageing. Six types of concrete were produced for the purpose of the presented experiment and differed in the water/cement ratio and were otherwise identical as to the input components. SilverSchmidt PC L test hammer was used to determine the rebound coefficient Q and compressive strength of cube test specimens. The aim of the experiment was to verify the possibility of creating a conversion relationship between the determined parameter of the used non-destructive method and the real compressive strength of concrete in the first days of ageing of concrete. Based on the conducted experiment, it may be stated that the SilverSchmidt PC L test hammer with a mushroom plunger is a suitable instrument for determining the initial compressive strength of concrete, starting from the value of about 5 N/mm2. An important conclusion is the fact that it is possible to create a regression model with relatively high accuracy, in this case approximately ± 3 N/mm2.
  • Thumbnail Image
    Item
    Determining reinforcement coverage using an electromagnetic rebar detector
    (IOP Publishing, 2018-07-16) Cikrle, Petr; Anton, Ondřej; Kinclová, Anežka; Kocáb, Dalibor
    Correct reinforcement is an essential part of constructing reinforced concrete structures. Errors in positioning, diameter, or coverage may result in defects, which is why it is necessary to make sure the reinforcement is implemented well. Even though electromagnetic detection is the most common non-destructive method for locating reinforcement in reinforced concrete, science literary sources hardly discuss it. The main reason is a lack of graphic test results – thus far the most common research outcomes have been photographs of lines drawn on the concrete surface or additions to technical drawings of the reinforcement. Only modern detectors expanded the possibilities of the method’s application including graphic measurement records and a more accurate estimation of reinforcement diameter including corrections for adjacent reinforcement spacing. The paper focuses on the principle of measurement and practical examples of determining the position and coverage of reinforcement in reinforced-concrete structures using a state-of-the-art electromagnetic rebar detector – a Profometer PM-630. Aside from data recording and statistical evaluation during coverage measurement, modern instruments also allow the data to be exported and visualised.