Bio: Agnieszka Różycka is an academic researcher from AGH University of Science and Technology. The author has contributed to research in topics: Specific surface area & Crystallization. The author has an hindex of 5, co-authored 10 publications receiving 252 citations.
TL;DR: In this article, the system of different Ca/Si and Al/Si molar ratios were investigated and it was shown that incorporation of Al increases main basal spacing, amount of bounded water and decreases crystallinity of C-(A)-S-H (calcium (aluminium) silicate hydrate).
Abstract: Systems of different Ca/Si and Al/Si molar ratios were investigated. Incorporation of Al increases main basal spacing, amount of bounded water and decreases crystallinity of C-(A)-S-H (calcium (aluminium) silicate hydrate). Transmission electron microscope observations showed that aluminium results in formation of more compacted, foil-like microstructure. FTIR revealed the presence of rings within the structure of C-(A)-S-H. Low Ca/Si ratio promotes Al incorporation into C-(A)-S-H, while in case of high Ca/Si ratio aluminium is also incorporated into AFm. The results show, that Ca/Si ratio is of key significance deciding on Al incorporation into C-(A)-S-H in hydrating SCMs bearing blended systems.
TL;DR: In this article, the influence of expanded perlite waste on the properties of autoclaved aerated concrete (AAC) was investigated, and the structural and microstructural properties of AC were investigated.
Abstract: In presented paper, the influence of expanded perlite waste on the properties of autoclaved aerated concrete (AAC) was investigated. Expanded perlite waste was used as a quartz sand replacement in conventional AAC mixtures at 5%, 10%, 20%, 30% and 40% by weight. Results show that use of expanded perlite waste in AAC caused a unit weight decrease in the produced AAC, it is connected with the changes in the properties of AAC. The thermal conductivity coefficient and compressive strength of specimens decreased as the amount of expanded perlite waste increased in AAC. The introduction of perlite waste up to 10% by weight reduced the thermal conductivity about 15% without significant reduction of compressive strength. Further improvement of thermal conductivity may be obtained by the addition of perlite waste up to 30%, but it caused reduction compressive strength about 20%. The minimum thermal conductivity value was 0.074 W/m·K, observed at 40% expanded perlite waste replacement. The structural and microstructural investigations showed that expanded perlite waste has a positive influence on the formation of calcium silicate hydrates (1.1 nm tobermorite) in AAC. From this result, it was concluded that expanded perlite waste can potentially be used as quartz sand replacement in the production of AAC.
TL;DR: In this paper, a method of utilization of waste expanded perlite as a valuable, high performance pozzolanic supplementary cementitious material was presented, which can be used as both cement substitute as well as cement additive depending on desired properties of final material.
Abstract: Expanded perlite is a valuable lightweight material for building materials industry as well as for agriculture, horticulture etc. Unfortunately during both production as well as processing of expanded perlite, some fine grained waste perlite is being formed. Due to its extremely low bulk density waste expanded perlite is difficult to handle, utilize and causes dust formation. Paper presents method of utilization of waste expanded perlite as a valuable, high performance pozzolanic supplementary cementitious material. Waste expanded perlite was ground in ball mill in order to destroy cellular microstructure of waste expanded perlite. It resulted in significant increase in specific surface area of material. Results of strength tests showed, that addition of ground waste expanded perlite may result in strength gain up to 50% (for 35% addition in respect to cement mass). Due to its high activity ground waste expanded perlite can be used as both cement substitute as well as cement additive depending on desired properties of final material. Investigations showed, that ground waste expanded perlite is material of pozzolanic activity. Except strength test, pozzolanic activity was investigated by solubility test according to ASTM C379-65T. Direct measurements of calcium hydroxide content in hydrating alite pastes confirmed that ground expanded perlite reacts with calcium hydroxide what results in reduction of calcium hydroxide content in alite paste. Pozzolanic activity of ground waste expanded perlite was compared with commonly used commercial pozzolanas. Obtained results allow to classify ground waste expanded perlite as material of pozzolanic properties. It can be valuable supplementary cementitous material mainly for special applications due to its high pozzolanic activity and very bright, almost white colour. In addition to that, ground waste expanded perlite used as cement replacement allows to decrease carbon dioxide emission, since Portland cement manufacturing is connected with emission of considerable amount of carbon dioxide.
TL;DR: In this paper, the authors evaluated the thermal conductivity of autoclaved aerated concrete (AAC) and showed that it has better thermal properties than sand AAC in the same density.
Abstract: In recent years the evaluation of U-value for buildings materials has been seen. Since 1st January 2014 U-value can’t be higher than 0,25 [W/m2K], but since 2017 this value will be 0,23 and 0,20 from 2021. Therefore, a good solution to fulfill mentioned conditions is using buildings material with better thermos insulation. One of the best construction materials, which have very low λ value [W/mK] is an autoclaved aerated concrete (AAC). It's the reason why AAC is the most popular buildings material from years. AAC could be produced with using various aggregates, like sand or fly ash. Test results of thermal conductivity clearly shown that AAC based on siliceous fly ash have better λ value than sand AAC in the same density. Polish energy policy is based on coal and production AAC based on siliceous fly ash is a great solution to utilization this waste. Autoclaved aerated concrete has better λ value than other available construction materials in polish market. Lower density have good impact on environment, because lower weight caused possibility to transport more products by the same truck and also it means less waste from buildings made from AAC in the future. This waste can be used again in normal production process of AAC. Due to these facts were undertaken studies of possibility of production AAC in 350 [kg/m3] density in PGS process technology. The PGS process technology is a very specific because in a production cement is not used. As a binder are used only: quick lime, gypsum and some part of fly ash. The most important properties of AAC were tested, like: compressive strength, density, λ value or phase composition. Production AAC in lower density could be the next step to improve that it's an environmental friendly material for energy-efficient constructions.
TL;DR: In this article, the intercalation of smectite clay with gentamicin (an aminoglycoside antibiotic) was investigated by means of X-ray diffraction, Fourier transform infrared spectroscopic techniques and transmission electron microscopy and scanning-electron microscopy with energy-dispersive spectroscopy Xray analysis.
Abstract: This paper focusses on the intercalation of clay mineral with gentamicin (an aminoglycoside antibiotic). The smectite clay–gentamicin hybrids were prepared by a solution intercalation at 60∘C and the process was carried out on unmodified smectite clay and on smectite after Na+ ionic activation. The resulting structural/microstructural properties and the potential for introducing gentamicin between smectite clay layers were investigated by means of X-ray diffraction, Fourier transform infrared spectroscopic techniques and transmission electron microscopy and scanning electron microscopy with energy-dispersive spectroscopy X-ray analysis. The results confirm the successful intercalation of gentamicin into the interlayer space of smectite clay, demonstrating that the material thus obtained could potentially be used as a drug carrier.
TL;DR: The development of low-carbon binders has been recognized as a means of reducing the carbon footprint of the Portland cement industry, in response to growing global concerns over CO2 emissions from the construction sector as mentioned in this paper.
Abstract: The development of low-carbon binders has been recognized as a means of reducing the carbon footprint of the Portland cement industry, in response to growing global concerns over CO2 emissions from the construction sector. This paper reviews recent progress in the three most attractive low-carbon binders: alkali-activated, carbonate, and belite-ye'elimite-based binders. Alkali-activated binders/materials were reviewed at the past two ICCC congresses, so this paper focuses on some key developments of alkali-activated binders/materials since the last keynote paper was published in 2015. Recent progress on carbonate and belite-ye'elimite-based binders are also reviewed and discussed, as they are attracting more and more attention as essential alternative low-carbon cementitious materials. These classes of binders have a clear role to play in providing a sustainable future for global construction, as part of the available toolkit of cements.
TL;DR: In this paper, the authors report an in-depth review of foam concrete in terms of its components, fresh state and physical properties like consistency, stability, workability, drying shrinkage, air-void system and water absorption.
Abstract: With the increase in global warming, the construction sector is trying to find an alternative to ordinary concrete due to its high dead weight and thermal conductivity. Researches are going in different directions and presently the emerging trend is the use of foamed concrete, which is a lightweight concrete having more strength-to-weight ratio with density varing from 300 to 1800 kg/m3. This reduces the dead load on the structure, cost of production and labour cost involved during the construction and transportation. Also, the large number of pores in the foam concrete reduces the thermal and sound absorption, thus making the structure appropriate for all climatic conditions. The paper reports an in-depth review of foamed concrete in terms of its components, fresh state and physical properties like consistency, stability, workability, drying shrinkage, air-void system and water absorption. It also includes a brief review of foam concrete prepared using various types of foams such as chemically expanded and air cured foams. Various mechanical properties like compressive strength, flexural strength and elastic modulus are also discussed. In addition, to have more understanding about the variable aspects that promote a better habitable atmosphere for all climatic conditions functional characteristics like thermal conductivity, fire resistance, acoustic properties and resistance to aggressive environment are also presented. Apart from this, the paper reports a brief outline of various applications of foam concrete.
TL;DR: In this paper, the effects of FA addition on the compressive strength f cm and fracture toughness of plain concrete are presented, and the results of the K Ic S and the f cm are convergent qualitatively.
Abstract: Nowadays green buildings are a necessary component of securing sustainability, whereas concrete composites with the addition of siliceous fly ash (FA) can certainly be included in the sustainable and green concrete. Effective promotion of green concrete incorporating FA is required in order to minimize the environment threat due to FA waste disposal and reduce cement consumption. In this paper, effects of FA addition on the compressive strength f cm and fracture toughness of plain concrete are presented. Fracture toughness tests were carried out according to Mode I (tension at bending) following the RILEM Draft Recommendations. The critical values of stress intensity factors, K Ic S have been determined. To assess mechanics parameters compressive strength tests and fracture toughness tests were conducted and the results were evaluated comparing with reference concrete. In modified concretes, cement was replaced by FA by its weight. Three test groups were constituted with the replacement percentages as: 0% (FA-00), 20% (FA-20) and 30% (FA-30). During the tests, the effect of age of concretes modified with the additive of FA on analysed parameters was determined. The experiments were carried out after: 3, 7, 28, 90, 180 and 365 days of curing. Based on the obtained results it can be concluded that, it is possible to make green concrete containing FA with high compressive strength and fracture toughness. The properties of composites with the additive of FA depend on the age of the concrete during tests. 20% additive of FA guarantees high f cm and K Ic S in mature concretes. Moreover results of the K Ic S and the f cm are convergent qualitatively.
TL;DR: Autoclaved aerated concrete waste (AACW) is a common low-strength cement-based construction and demolition waste, which is currently disposed by landfills and hard to be directly used as supplementary cementitious material as discussed by the authors.
Abstract: Autoclaved aerated concrete waste (AACW) is a common low-strength cement-based construction and demolition waste, which is currently disposed by landfills and hard to be directly used as supplementary cementitious material. The present work proposed a potential approach incorporating AACW for cement substitution in sustainable building materials. Wet-milling technique was used to dispose and improve the fineness of AACW (median particle size, as low as 2.3 μm). It was proved that AACW is suitable for wet-milling treatment due to its porous texture and low-strength. The pH value and electrical conductivity of the AACW slurry was notably improved. Water requirement was increased by the ultrafine AACW. Both setting time and the main hydration heat location were obviously brought forward by ultrafine AACW, indicating its early hydration acceleration. Compressive strength of ultrafine AACW replaced cement pastes present higher or equivalent value compared with pure cement paste, within 30% replacement level. Pore structure was effectively refined by the ultrafine wet-milling AACW. It was proved that AACW could be efficiently used as an alternative cementitious material in cement and concrete after wet-milling treatment, thus bring environmental and economic benefits.
01 Jan 2007
TL;DR: In this paper, Sertraline hydrochloride was intercalated in the interlayer spacing of the clay by cation exchange and was loaded inside the MCM-41 channels by pore volume impregnation means.
Abstract: Sertraline hydrochloride (designated as sertraline from now on) is an antidepressive drug with unpleasant effects in the gastric tract. Therefore, improved means of delivery allowing for a more controlled and efficient release were looked for. Two different porous materials, montmorillonite-K10 and MCM-41, were chosen as hosts. The drug was intercalated in the interlayer spacing of the clay by cation exchange and was loaded inside the MCM-41 channels by pore volume impregnation means. Spectroscopic evidence (UV/vis, FTIR, powder X-ray diffraction (XRD) and 13 C CP/MAS and 29 Si CP/MAS and MAS solid-state NMR), as well as elemental analysis, complemented by DFT calculations, demonstrated the presence of sertraline in the composite materials. The release processes were monitored under in vitro conditions using a simulated body fluid. The release profile from the clay is fast, indicating that a concentration peak is reached in a short period of time, while the release profile from MCM is slower but lasts longer. These differences are discussed on the basis of different therapeutic indications for both materials. 2006 Elsevier B.V. All rights reserved.