Opening of Microcracks and Air Permeability in Concrete

Stehlík, Michal; Heřmánková, Věra; Vítek, Lubomír

doi:10.3846/13923730.2013.802721

Cited by 5 publications

(3 citation statements)

References 18 publications

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“…1 Porosity is influenced mainly by the amount of water needed for cement hydration, air voids produced by inadequate concrete compaction or by air-entrainment (content, size and distribution of air voids), cracks formed during hydration due to volume changes and other factors. [5][6][7] The quality of the surface layer together with the porosity of the concrete also determines its resistance to the intrusion of liquids and gases from the environment, i.e., permeability. Permeability is determined, e.g., by TPT [5][6][7][8] , GWT and ISAT.…”

Section: Introductionmentioning

confidence: 99%

“…[5][6][7] The quality of the surface layer together with the porosity of the concrete also determines its resistance to the intrusion of liquids and gases from the environment, i.e., permeability. Permeability is determined, e.g., by TPT [5][6][7][8] , GWT and ISAT. 9 Other options for assessing the surface layer of concrete are methods for determining the resistance of cement concrete to water and de-icing chemicals.…”

Section: Introductionmentioning

confidence: 99%

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Experimental determination of the influence of fresh concrete’s composition on its resistance to water and de-icing chemicals by means of two methods

Kocáb¹,

Komárková²,

Králíková³

et al. 2017

Mater. Tehnol.

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Concrete's durability is currently a frequently discussed topic. The determination of concrete's durability is rather difficult since it depends on a number of factors, out of which the surface-layer quality is very important. One of the options for assessing its quality is the determination of concrete's resistance to water and de-icing chemicals. The testing is based on loading the concrete by cyclic freezing and thawing during the simultaneous action of a thawing solution. The damage to the surface layer manifests itself as scaling, i.e., the loss of small scales from the surface of the material. The resistance of concrete to water and de-icing chemicals can be determined by means of several methods; however, a universal method of evaluation has not yet been established in Europe. The goal of the experiment described here was to assess the influence of fresh concrete's composition on its resistance to water and de-icing chemicals using two different measurement methods (method A and C). A total of 9 fresh concrete mixtures were designed, from which specimens were made. The experiment was created and evaluated using the statistical method DOE (Design of Experiment). Based on the tests performed, it can be stated that a change in the content of cement and plasticiser in fresh concrete is visible in the results of both methods. However, more so in the results for method C, which is generally more sensitive to changes in fresh concrete's composition. Keywords: concrete, resistance, durability, de-icing chemicals Zdr`ljivost betona je pogosto obravnavana tema. Dolo~anje zdr`ljivosti betona je precej te`ko, ker je odvisno od {tevilnih faktorjev, med katerimi je pomembna tudi kvaliteta povr{inske plasti. Ena od opcij dolo~anja njene kvalitete, je dolo~anje odpornosti betona na vodo in na kemikalije proti zmrzovanju. Preizkus temelji na izpostavitvi betona cikli~nemu zamrzovanju in odtaljevanju s simultanim delovanjem raztopine za odtaljevanje. Po{kodbe povr{inskega sloja se ka`ejo kot lu{~enje povr{ine materiala. Odpornost betona na vodo in kemikalije za raztaljevanje se lahko dolo~i z ve~metodami; vendar pa univerzalna metoda za oceno tega v Evropi {e ni vzpostavljena. Cilj opisanih eksperimentov je bil oceniti vpliv sestavo sve`ega betona glede na njegovo odpornost na vodo in na kemikalije za raztaljevanje, z uporabo dveh metod (metoda A in C). Skupno je bilo pripravljenih 9 sve`ih betonskih me{anic iz katerih so bili izdelani vzorci. Eksperimenti so bili postavljeni in izvedeni z uporabo statisti~ne metode DOE (postavitev preizkusa). Na podlagi izvedenih preizkusov se lahko zaklju~i, da se spremembe v vsebnosti cementa in plastifikatorja v sve`em betonu poka`ejo pri obeh metodah. Vendar so bolj izrazite pri rezultatih metode C, ki je na splo{no bolj ob~utljiva na spremembe v sestavi sve`ega betona.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental determination of the influence of fresh concrete’s composition on its resistance to water and de-icing chemicals by means of two methods

Kocáb¹,

Komárková²,

Králíková³

et al. 2017

Mater. Tehnol.

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“…A number of papers have been published within the project, such as 8,9 . Permeability itself is addressed in [10][11][12] . The research described in this paper summarises an experiment whose goal was to assess the influence of concrete composition on the results of the tests determining the concrete surface layer's permeability, i.e., TPT, GWT and ISAT.…”

Section: Introductionmentioning

confidence: 99%

Statistical view of evaluating concrete-surface-layer permeability tests in connection with changes in concrete formula

Misák¹,

Stavař²,

Rozsypalová³

et al. 2017

Mater. Tehnol.

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Concrete is one of the most common building materials and its durability has been observed with increased attention. It can be said that concrete durability is closely connected with permeability and, generally speaking, the quality of its surface layer. Evaluating the quality of the surface layer of concrete is a rather difficult issue that can be addressed in different ways. The authors of this paper focus on three internationally used methods -TPT, GWT and ISAT. The paper sums up the results of the experiment whose goal was to investigate the influence of concrete composition on the outputs of the above-mentioned methods. For the purposes of the experiment, specimens were made using 9 mixtures, which differed only in the amount of cement and plasticiser, i.e., the water/cement ratio. The experiment was designed and evaluated using the statistical methodology DOE (Design of Experiment). Next, the paper discusses a new view of the statistical evaluation of the test results of the methods described above. Keywords: concrete, permeability, durability, design of experiment Beton je eden najbolj uporabljanih materialov v gradbeni{tvu in njegova zdr`ljivost se prou~uje z veliko pozornostjo. Lahko se re~e, da je zdr`ljivost betona tesno povezana s prepustnostjo, na splo{no s kvaliteto njegove povr{inske plasti. Ocena kvalitete povr{inske plasti betona je precej komplicirano vpra{anje, h kateremu se lahko pristopi na razli~ne na~ine. Avtorji tega~lanka se osredoto~ajo na tri mednarodno priznane metode -TPT, GWT in ISAT.^lanek povzema rezultate preizkusa, katerega cilj je bil prou~evati vpliv sestave betona na rezultate zgoraj omenjenih metod. Za namene preizkusa so bili vzorci izdelani iz 9 me{anic, ki so se razlikovale samo v koli~ini cementa in plastifikatorja, to je razmerja voda/cement. Preizkusi so bili postavljeni in ocenjeni s statisti~no metodologijo DOE (angl. Design of Experiment). Nadalje~lanek obravnava nov pogled na statisti~no oceno rezultatov preizkusa in zgoraj opisanih metod.

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