The aim of the paper is to outline the possibilities and predictive values of the selected methods for determining air-pore characteristics in concrete and cement composites in general. Four samples (mixtures) of cement concrete without additives or admixtures were chosen for the measurement, differing in cement content while maintaining the consistency of fresh concrete S3 according to EN 206. Both standardized and non-standardized methods are used in Europe, therefore providing a possibility of comparing their outcomes. Keywords: concrete, durability, porosity, surface, covering layer, X-ray computed micro-tomography Namen~lanka je prikazati mo`nosti za splo{no napovedovanje izbranih metod za dolo~anje zna~ilnosti zra~nih por v betonu in v kompozitih iz cementa. Za meritve so bili izbrani {tirje vzorci (me{anice) betona brez dodatkov in primesi z razli~no vsebnostjo cementa ob zadr`anju konsistence sve`ega betona S3, skladno z EN 206. Standardizirane in nestandardizirane metode se uporabljajo v Evropi in zato omogo~ajo primerjavo rezultatov.
The paper describes an experiment focused on observing the development of the elastic modulus and compressive strength in a polymer-cement mortar during the first 28 days of aging. The specimens (aged 3 and 28 days) were tested for the static and dynamic modulus of elasticity using two methods – the ultrasonic pulse velocity test and the resonance method. During the test of the modulus of elasticity in compression the mortar’s behaviour was also examined by means of the acoustic emission method, which is based on the recording of mechanical pulses caused by dilation waves generated by microcracks that form during loading. The outcome of the experiment is an evaluation of the polymer-cement mortar’s behaviour in terms of the development of its elastic modulus and compressive strength as well as in terms of the material’s acoustic response during loading.
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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