Papers by Danute Vaiciukyniene
Construction and Building Materials, Jul 1, 2023
Two-dimensional carbon fiber reinforced zirconia matrix composites have been fabricated by slurry... more Two-dimensional carbon fiber reinforced zirconia matrix composites have been fabricated by slurry infiltration and hot pressing techniques. The room temperature mechanical properties were investigated and the fracture features of composites were observed. The results showed that with the increase of temperature the relative density of as-prepared C f /ZrO 2 composites increased. But the mechanical properties of composites on fiber configuration firstly increased and then decreased. Higher mechanical properties were obtained for the composite hot-pressed at 1500 1C i.e. the flexural force and fracture energy were 136.0 N and 31.3 kJ Á m À 2 respectively. SEM observation revealed fiber pull-out in the composite sintered at ≤1500 1C. For the composite sintered at a higher temperature, however, chemical diffusion between fiber and ZrO 2 was found by HRTEM, which indicates the formation of strong bonding. Also the reduced nonlinear region and short pullout length of fiber suggest a strong interfacial bonding between the fiber and matrix. The strong interfacial bonding and large thermal residual stress mainly contribute to the degradation of mechanical properties above 1500 1C.
Waste and Biomass Valorization, Apr 13, 2020
Phosphogypsum (further PG) is a by-product obtained from the production process of the phosphate ... more Phosphogypsum (further PG) is a by-product obtained from the production process of the phosphate fertilisers. It is produced in enormous quantities, but only 15% of it is recycled. The remaining part is stored in large stockpiles or in water bodies. The harmful water-soluble impurities present in PG composition cause serious ecological complications; therefore, in order to solve this problem, it is crucial to find a useful and large-scale application. In this study, the suitability of the press-formed PG to be used as a binding material is investigated. Three important aspects are considered: the neutralisation of impurities, the degree of hydration and the compressive strength. The addition of the hydrated lime additive in the PG mixture was found to be an effective way to bind the water-soluble harmful phosphates into non-soluble compounds, solving the environmental problem which could limit its application. Moreover, "two-step hydration process" was proven to be a useful way to achieve a higher degree of hydration of the hardened PG specimens. Finally, the press-forming process was found to be an economic way to improve the compressive strength of PG specimens and, therefore, a good alternative to the usage of more expensive additives such as cement. The optimal combination of the compressive strength and the degree of hydration was achieved. In conclusion, the application of press-formed PG in building materials is an economic and efficient way to solve the environmental problems which it is causing today.
Scientific Reports, Jan 15, 2020
In the petroleum industry during a catalytic cracking process, the used zeolitic catalyst becomes... more In the petroleum industry during a catalytic cracking process, the used zeolitic catalyst becomes waste. this article investigated the sorption capacities of ammonium ions from aqueous solutions onto the previously mentioned zeolitic waste by batch experiments. Three types of zeolitic waste were used: unmodified zeolitic waste with two different particle size distributions and H 2 o 2-modified zeolitic waste. Several techniques, including X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) multilayer adsorption theory measurements, and X-ray fluorescence analysis (XRF) were used to demonstrate experimentally that the zeolitic waste could be used as a sorbent for the water decontamination of NH 4 + ions. The morphology of zeolitic waste investigated by scanning electron microscopy (SEM) revealed particles with a spherical shape. The nitrogen adsorption-desorption isotherms showed an isotherm mixture of types I (pure microporous) and IV (mesoporous). This suggested that the investigated zeolitic materials were mesoporous (4.84 nm) and microporous (0.852 nm), as well as containing slit/cylindric pores, according to a quench solid density functional theory (QSDFT) adsorption branch model. Zeolitic waste from the oil industry showed good NH 4 + sorption properties (removal efficiency of 72%), thus becoming a potential adsorbent to be used in the treatment of contaminated aqueous effluents polluted with ammonium ions. Simultaneous waste and water decontamination can be achieved, providing a new tool and enhanced capabilities for environmental remediation. Ammonium (NH 4 +) is one of the common form of reactive nitrogen in wastewater 1 , and its contamination in fish causes serious health problems due to its high toxicity. The technologies for ammonia removal from wastewater are based on physicochemical and biochemical treatment methods 2. One of these treatment methods is adsorption, which is a low-cost process. Different adsorbents, such as wheat straw biochars, pine sawdust or zeolites, can be effective in adsorbing ammonium in wastewater 3-13. Yang et al. 4 used some natural adsorbents such as pine sawdust and wheat straw biochars for the ammonium removal in wastewater. It was concluded that biochars can be efficient absorbents for NH4 + removal from aqueous solutions. Tian et al. 5 synthesized a new sorbent using modified coal cinders and zeolite powders. This sorbent has been shown to be a good material for the removal of ammonia nitrogen. The removal efficiency of ammonia nitrogen was 67.3% and 71.3%. The inflow concentrations of ammonia nitrogen were obtained under the experimental conditions where chemical oxygen demand under a water flow of 10 L/h. Yin et al. 6 used NaCl-modified clinoptilolite as adsorbent for the nitrogen removal. Results in a current batch study provided that the maximum ammonium sorption capacity of clinoptilolite was in the range of 6.64 to 7.27 mg. N/g. The work reported by Sánchez-Hernández et al. 7 evaluated the use of NaP1 zeolite for the removal of ammonium from aqueous solutions. The experiment of ammonium removal was conducted by the batch experiments. This zeolite was obtained from a hazardous Al-containing waste. These results indicate that the duration of the NH 4 + uptake on NaP1 was fast. Ammonium was removed within 15 minutes with high
Minerals, Sep 8, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Journal of building engineering, Feb 1, 2021
The production of by-product phosphogypsum is very problematic. In order to recycle the phosphogy... more The production of by-product phosphogypsum is very problematic. In order to recycle the phosphogypsum into a building material, its harmful acidic impurities (especially the soluble phosphate) should be purified, and the mechanical properties improved. Therefore, in this study, a novel method of processing the phosphogypsum is proposed. It consists in the addition of waste zeolite to adsorb the phosphate impurities, and in the application of press-forming processing to improve the compressive strength of the hardened specimens. The zeolite additive has proven to be an efficacious adsorbent, which reduced the soluble phosphate content by 3.2-7.5 times and surprisingly improved the hydration degree of the phosphogypsum. Moreover, the press-forming of phosphogypsum by applying 15 and 20 MPa pressure produced specimens with a compressive strength over 50 MPa.
Materials, Nov 15, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Scientific Reports, Jan 20, 2020
Vaičiukynienė, Gintautas tamošaitis & Rėda Bistrickaitė currently, the production of green buildi... more Vaičiukynienė, Gintautas tamošaitis & Rėda Bistrickaitė currently, the production of green building materials grows up. Alkali-activated materials (AAMs) based plaster have better fire resistance properties compared to Portland cement-based concrete and plasters. Compared to Portland cement-based systems AAMs retain a significant level of structural stability after exposure to fire events. AAM based concrete doesn't have at all or has an insignificant amount of calcium hydroxide in the binder structure which exposed to high-temperature changes to calcium oxide. this weakens portland cement structural properties and allows cracks to appear under high-temperature conditions. this study shows that AAM based plaster that consisted of alkaliactivated ground granulated blast furnace slag (slag) with the addition of phosphogypsum (pG), sand and polypropylene fibre filling exposed to 1000 °C temperature shows up to 2% longitudinal dimension shrinkage. After exposure of elevated temperature these fibers melted leaving a network of channels that allow water vapour vaporize and inner pressure in the material decreased. the start of the wood surface charring process t ch is 10 minutes after the start of heating. Using an AAM binder as fire-resistant plaster coating on a wooden structure delays the start of the char layer forming on the wood surface. This allows using AAMs base plaster for fire-resistant coatings on combustible materials as the barrier layer in order to increase the passive safety of wooden structures in heritage buildings.
Construction and Building Materials, Sep 1, 2018
h i g h l i g h t s PG shortens the setting times of alkali activated slag cured at room temperat... more h i g h l i g h t s PG shortens the setting times of alkali activated slag cured at room temperature. During hydration process sodium sulfate forms in alkali activated specimens. The highest compressive strength of specimens is with 5% of PG. The specimens with 5% of PG exhibit greater residual strength.
Journal of building engineering, Dec 1, 2021
Abstract Phosphogypsum (PG) is a by-product with an enormous potential to be used in construction... more Abstract Phosphogypsum (PG) is a by-product with an enormous potential to be used in construction products as a binding material. However, the performed studies are often focused on narrow aspects regarding its properties, and rarely consider the big picture. Hence, a comprehensive study of the influence of the origin, the microstructure, the chemical composition, and the processing procedures (either casting or press-forming) on the radiological, physical and mechanical properties of PG specimens was performed, by carrying out a comparative analysis of the properties of three PG types from different origins. The PG from igneous phosphate ores resulted the best material from all points of view.
Solid State Phenomena, Jun 1, 2018
The influence of the fine particle content on the rheological properties of the fresh concrete mi... more The influence of the fine particle content on the rheological properties of the fresh concrete mixture was studied. The change of cement together with sand particles up to 0.25 mm in mixture composition was taken into the consideration. The amount of fine particles in mixture composition varied in the range from 402 to 639 kg per one cubic meter of the concrete mixture. Technological properties of the concrete mixture were established according to the standardized requirements, rheological properties: yield stresses and viscosity of conventional concrete mixture were calculated based on analytical formulas. According to obtained test results, the increase of fine particle content from 481 to 520 kg in mixture reduced the yield stresses from about 557 to 132 Pa. Further increase of fine particle content from 600 to 639 kg showed the rise of yield stress by 3.87 times. On the other hand, the viscosity of concrete mixture gradually decreased (ca. 5.6 times). To sum up, the rheological properties of the concrete mixture were significantly influenced by the content, packing density, fineness, surface texture and particle size distribution of fine particles.
Journal of Sustainable Architecture and Civil Engineering, Feb 9, 2017
Alkali activation is a highly active and rapidly developing field of activity in the global resea... more Alkali activation is a highly active and rapidly developing field of activity in the global research. Alkaliactivated cements have found a variety of applications: transportation, industrial, agricultural, residential, mining and so on. Alkali activated binders are made by mixing industrial aluminosilicate waste materials such as one of them is slag. This study aims to evaluate the influence of incorporating aluminum hydroxide on the physical and mechanical properties of alkali-activated slag. Mineralogy of composites were studied using X-ray diffraction analyze. The results showed that the molar ratio of raw materials strongly affects the kinetics of reaction and the structural evolution of the solid phases forming in alkali silicate activated binders. The role of Al(OH) 3 in the mixtures in activated binders is closely related to the availability of Al in the system, because it controls the concentrations of secondary products such as zeolites. Based on the experimental results, it can be concluded that by reducing Al 2 O 3 from 1.30 mol till 0.75 mol (in the mixtures of raw materials) the compressive strength of samples increases from 27-42 MPa till 39-54 MPa.
Materials, May 9, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Social Science Research Network, 2022
Construction and Building Materials
Minerals
Fluid catalytic cracking (FCC) catalysts, used in the petroleum industry, are sources of zeolitic... more Fluid catalytic cracking (FCC) catalysts, used in the petroleum industry, are sources of zeolitic by-products. These by-products are often used as sorbents for the removal of ammonium ions from wastewater. After a period of use, the zeolitic by-product loses its sorption properties and is no longer effective. The problem is the use of zeolitic by-product with ammonium ions. In this study, a zeolitic by-product containing ammonium ions and high contents of active SiO2 and Al2O3 was used as a supplementary cementitious material (SCM). Cement pastes containing 0.5%, 1%, 3%, 5%, and 10% of the by-product were prepared, and the compressive strength and density of the pastes were evaluated. Incorporation of the zeolitic by-product increased the cement strength by 17% and 32% after 7 and 28 days of hydration, respectively. Thus, incorporation of the zeolitic by-product with ammonium ions as an SCM has a complex effect on an ordinary Portland cement (OPC) system. Ammonium chloride accelerat...
To explain some aspects about the mechanism of zeolite synthesis from reagent materials, law temp... more To explain some aspects about the mechanism of zeolite synthesis from reagent materials, law temperature (100 oC) hydrothermal reaction was performed in alkali solutions by using sonochemically-assisted pre-treatment method. This pretreatment method reduces the formation times of zeolites. Clear-to-the-eye sodium aluminosilicate gels and solid sodium aluminosilicate mixtures were used as raw materials. By using sodium aluminosilicate gels, it is observed that after hydrothermal treatment and sonication up to 10 minutes samples exhibit a rise in the crystallinity of Na-A zeolite up to 1.44 times, compared to a sample without sonication. When solid components as raw materials were used, the application of ultrasound irradiation and hydrothermal treatment resulted in the replacement of Na-A zeolite crystals to Na-X zeolite, which is a more stable zeolitic phase. In both cases Na-A zeolite was not detected in the synthesized products by using only sonication without the using of hydroth...
Ultrasonics Sonochemistry
Materials, 2021
Concrete plants accumulate large amounts of concrete wash water. This water, which pH is highly a... more Concrete plants accumulate large amounts of concrete wash water. This water, which pH is highly alkaline, has a negative impact on the environment. Its reuse in fresh concrete slightly reduces its mechanical properties. The combination of concrete wash water and zeolitic by-product led to an increase of 4.6% in the compressive strength at 7 days hydration and up to 30% at 28 days hydration. The same combination led to the denser microstructure compared to the samples made with concrete wash water. This could be explained by the pozzolanic reaction of the zeolitic by-product. The complex chemical reactions of cement, zeolitic by-product, and fines presented in the concrete wash water occurred. Therefore, it was suggested the reusing method of concrete wash water together with zeolitic by-product in the fresh concrete mixtures by substituting some amount of tap water with concrete wash water. In this way, the consumption of tap water is possible to reduce in cement systems.
Uploads
Papers by Danute Vaiciukyniene