Papers by Barbara Kucharczyková
The aim of the paper is to present the results of the experiment focused on the development of th... more The aim of the paper is to present the results of the experiment focused on the development of the mechanical fracture characteristics of alkali-activated slag (AAS) based composites within the time interval from 3 days to 2 years of ageing. Two AAS composites, which differed only in the presence of shrinkage reducing admixture (SRA), were prepared for the purpose of experiments. The composites were prepared using ground granulated blast furnace slag activated by water-glass with silicate modulus of 2.0, standardized quartzite sand with the particle grain size distribution of 0−2 mm, and water. Commercially produced SRA was added into the second mixture in an amount of 2 % by weight of slag. The test specimens were not protected from drying during the whole time interval and were stored in the laboratory at an ambient temperature of 21 ± 2 °C and relative humidity of 60 ± 10 %. The prism specimens made of the abovementioned composites with nominal dimensions of 40 × 40 × 160 mm with the initial central edge notch were subjected to the fracture tests in a three-point bending configuration. The load F and displacement d (deflection in the middle of the span length) were continuously recorded during the fracture tests. The obtained F−d diagrams and specimen dimensions were used as input data for identification of parameters via the inverse analysis based on the artificial neural network, which aim is to transfer the fracture test response data to the desired material parameters. In this paper, the modulus of elasticity, tensile strength, and fracture energy values were identified and subsequently compared with values obtained based on the fracture test evaluation using the effective crack model and work-of-fracture method.
IOP conference series, Jul 1, 2018
The article deals with the cement-based flooring compounds, especially with the behaviour during ... more The article deals with the cement-based flooring compounds, especially with the behaviour during the early solidification process. A touch-less laser sensor and a cone-shaped mould were used for the measurement of the plastic settlement/shrinkage. The process of solidification and the strength development were determined using the ultrasonic pulse velocity measurement. Both test devices were equipped with the thermocouple to measure the real-time internal temperature evolution during solidification of the flooring compounds. The measurements presented in this paper proved to be useful for the clarification of the technological problems which arose during the manufacturing of the test specimens.
MATEC web of conferences, 2020
There are several methods for determination of the setting and early hardening in the cementitiou... more There are several methods for determination of the setting and early hardening in the cementitious composites. The most common method is using the Vicat apparatus. The major disadvantage of this method is that it is invasive and therefore the measurement results exhibit high variability. The paper deals with the continual monitoring of the process of setting and early hardening of a cement paste using the ultrasonic measurement. The innovative method of using the ultrasonic NDT method for determination of the setting times of cement paste is presented in the paper.
CRC Press eBooks, Feb 26, 2021
MATEC web of conferences, 2017
The paper focuses on the experimental determination of the dynamic and static compressive modulus... more The paper focuses on the experimental determination of the dynamic and static compressive modulus of elasticity of selected polymercement mortars and their comparison. The dynamic modulus of elasticity was determined by means of the ultrasonic pulse velocity test and the resonance method. The static compressive modulus of elasticity test was accompanied by a measurement of the material's behaviour using the acoustic emission method, the principle of which is the detection of mechanical dilation waves produced by changes and microscopic faults in the structure of the material. The advantage of the acoustic emission method is the possibility of detecting a crack before it can be found e.g. using a microscope. The outcome of the experiment is a detailed evaluation of the behaviour of polymer-cement mortars made using the values of the elastic modulus and acoustic response of the material during loading.
Transactions on Transport Sciences, Dec 1, 2009
This paper deals with the influence of periodic freezing on lightweight concrete characteristics.... more This paper deals with the influence of periodic freezing on lightweight concrete characteristics. Three different sets of lightweight concrete specimens were periodically freezing and non-destructively tested over time. Another three comparative sets of lightweight concrete specimens were tested at the same time and these sets were placed in water. The main aim was to determine and compare the dynamic elastic modulus values during and after 200 freeze-thaw cycles. The methods for this non-destructive testing were the ultrasonic impulse method and the resonance method.
Solid State Phenomena, Jun 1, 2019
This paper deals with the relationship between chemical processes in the early stages of hydratio... more This paper deals with the relationship between chemical processes in the early stages of hydration of alkali-activated slag, volume changes and the development of the microstructure of this material. Two test pastes were produced for the purpose of the experiment - one with and the other without an organic admixture (isopropyl alcohol). The pastes were used to monitor autogenous shrinkage by measuring volume changes and at the same time the changes in the material during setting and early hardening using a modern ultrasonic instrument Vikasonic. The output of the described experiment is a detailed evaluation of the difference in the behaviour of the used alkali-activated paste with and without the addition of an organic admixture.
Procedia Engineering, 2017
The paper deals with the experimental determination of the shrinkage progress of the polymer ceme... more The paper deals with the experimental determination of the shrinkage progress of the polymer cement (PCC) mortars. The main motivation of performed measurements was to compare the results obtained from two different measurement procedures based on the measurement of the relative length changes and relative mass losses of the test specimens during whole time of ageing. Performed experimental analysis, focused on the determination of the progress of the relative length changes and relative mass losses, showed advantages and disadvantages of investigated measurement procedures. All performed measurements exhibited almost the same total progress of relative mass losses regardless of the used test procedure and size of specimens. The differences in the relative length changes originated from the capabilities, limitations and regulations of particular measurement procedures.
Russian Journal of Nondestructive Testing, Mar 1, 2010
A quality of a covercrete (covercrete = cover concrete) up to a depth of 20–50 mm practically dec... more A quality of a covercrete (covercrete = cover concrete) up to a depth of 20–50 mm practically decides about the durability of concrete of a structure. The covercrete prevents accessing of acid substances from the atmosphere to steel reinforcement. For evaluation of a state of the covercrete from the durability viewpoint is possible to use a relatively new NDT method
American Concrete Institute, Journal of, 2020
Journal of physics, Sep 1, 2022
Alkali-activated systems belong to the group of alternative inorganic binders in which the binder... more Alkali-activated systems belong to the group of alternative inorganic binders in which the binder properties are dictated by both the aluminosilicate precursor and alkaline activator. In this work, blast furnace slag and three different alkaline activators, namely sodium hydroxide, sodium water glass, and sodium carbonate, were selected. An innovative mixture design based on the same concentration of alkali (Na+) of 4 mol/dm3 for all activators and different volume fractions of slag in pastes, ranging from 0.44 to 0.54, was investigated by the flow table test, compressive and flexural strength test, and by a shrinkage test under autogenous conditions. Great differences for various activators for all investigated parameters were obtained. The highest fluidity, regardless of volume fraction of the slag, was observed for the water glass, originating from a greatly decreased yield stress compared to the two other activators. The type of activator and the volume fraction of the slag also played a crucial role in the development of shrinkage and strength.
Key Engineering Materials, Aug 1, 2018
This paper deals with the influence of the coarse aggregate grain size on the frost resistance of... more This paper deals with the influence of the coarse aggregate grain size on the frost resistance of concrete. For the purpose of the experiment, three types of concrete were produced, varying only in the maximum grain size of the used natural aggregate. The evaluation of the frost resistance of concrete is based on non-destructive (NDT) dynamic and static testing methods. The results of the experiment indicate influences of the aggregate used in the production of the concrete on the results of its frost resistance.
Transactions on Transport Sciences, Dec 1, 2009
Current research and development of non-linear ultrasonic spectroscopy methods shows these method... more Current research and development of non-linear ultrasonic spectroscopy methods shows these methods to be very promising for material testing and defectoscopy in the near future. Our experiments focused on the testing of lightweight concrete specimens using the single-frequency excitation method. We studied the concrete specimens' structure after having been stressed by a mechanical force. Measurements were realized before and after mechanical loading.
Engineering Fracture Mechanics, Jun 1, 2023
Journal of physics, 2023
The paper presents the results of a pilot study focused on the shrinkage process and fracture par... more The paper presents the results of a pilot study focused on the shrinkage process and fracture parameters of two fine-grained materials prepared from ground granulated blast furnace slag and silica sand. Two different activators were used - liquid sodium silicate and sodium hydroxide. The components ratio and the activator dose were the same for both materials and were as follows: activator dose of 6% Na2O by the slag weight, 1% of lignosulfonate plasticizer, and the ratio of slag:water:sand of 1:0.45:3. All specimens matured at room temperature. For each material, four curing regimes were designed with respect to the potential application on-site (especially different upper surface treatment and demoulding time). The shrinkage measurement lasted more than 2.5 years, after which fracture tests were performed on the same sets of specimens. Although only a slight nuance was in designed curing conditions, the results showed different sensitivity of investigated materials and monitored parameters to the particular curing regimes.
IOP conference series, Sep 1, 2022
This paper aims to evaluate the effect of replacement of aggregate by recycled one on fracture re... more This paper aims to evaluate the effect of replacement of aggregate by recycled one on fracture response of selected composites. These are hemp fibre reinforced cement-based composites. Four different mixtures were prepared: in reference one, the only natural aggregate was used whereas in the other three mixtures, the natural aggregate was replaced by recycled one in the amount of 10, 25 and 50 %, respectively. All mixtures contained hemp fibres with a length of 10 mm in the dosage of 1 % by volume. In order to determine the selected mechanical fracture characteristics of the investigated composites, three-point bending fracture tests were carried out on prismatic specimens with nominal dimensions 40 × 40 × 160 mm3 provided with an initial notch. During the whole course of the testing, the loading process was governed by a constant displacement increment of 0.02 mm/min. The vertical displacement (midspan deflection) was measured using the inductive sensor mounted on a special measurement frame placed on the specimens. The fracture tests were terminated when the midspan deflection reached 0.5 mm. The mechanical fracture parameters were obtained through a direct evaluation of the fracture test data via the effective crack model and the work-of-fracture method. The paper shows that composites with a higher dosage of recycled aggregate (25 and 50 wt%) achieve similar values of mechanical fracture properties, so this replacement can be recommended.
IOP conference series, Jun 1, 2018
The paper deals with an experimental analysis focused on the determination and evaluation of the ... more The paper deals with an experimental analysis focused on the determination and evaluation of the early age shrinkage strain using Shrinkage-Cone. The measurements were performed on the cement pastes and mortars with a different w/c ratio. The authors propose a new approach to the measurement evaluation based on the determination of time-zero at the time of estimated initial setting determined as the time when the internal temperature of specimens started to rise. In this case, also the effect of the thermal expansion is taken into account in the evaluation.
MATEC web of conferences, 2017
The goal of the experiment was to determine the influence that cyclic loading has on concrete dyn... more The goal of the experiment was to determine the influence that cyclic loading has on concrete dynamic modulus of elasticity and compressive strength. Each test specimen was subjected to cyclic loading with the loading force equivalent to one third of the expected compressive strength value similarly to the static modulus of elasticity test with the difference that the total number of loading cycles was 3000. The dynamic modulus of elasticity was determined on every specimen before and after loading by means of the ultrasonic pulse velocity test and resonance method. The result of the experiment is the degree to which the dynamic modulus of elasticity decreased after multiple cyclic loading. A decrease was observed in all specimens.
Advances in Materials Science and Engineering, 2017
The paper deals with an experimental analysis focusing on the utilization of a specific measureme... more The paper deals with an experimental analysis focusing on the utilization of a specific measurement technique for determining the development of shrinkage and for monitoring structural changes in fine-grained cement-based composites during their ageing. Advanced measurement equipment and procedure allowing simultaneous measurement of length changes, mass losses, acoustic responses, and temperature development were designed and verified by the experimental investigation. The main scope of the experiments performed was focused on finding the relationships between the characteristics being investigated while maintaining a uniform test setup. For the purpose of the experimental measurement, three fine-grained cement composite mixtures were designed and manufactured. The mixtures differed in the water-to-cement ratio (w/c) and in the amount of plasticizer. The measurement outputs are presented in the form of diagrams showing the relations between the studied parameters, such as relative length changes, mass losses, temperature progress, and acoustic emission (AE) activity during solidification of the composites. The measurement results showed close relations between the examined characteristics. The progress of relative length changes together with the progress of mass losses and temperature development is reflected in the AE activity. The advanced measurement procedure and technique provided valuable information about the behaviour of cement-based composites during early setting and long-term hardening.
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Papers by Barbara Kucharczyková