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Tytuł:
Evaluation of Mechanical Properties of Lightweight Concrete with Pumice Aggregate
Autorzy:
Shafiq, Malik Salman
Khan, Fasih Ahmed
Badrashi, Yasir Irfan
Khan, Fayaz Ahmed
Fahim, Muhammad
Abbas, Asim
Adil, Waqas
Powiązania:
https://bibliotekanauki.pl/articles/2024034.pdf
Data publikacji:
2021
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
lightweight concrete
pumice lightweight aggregate
saline water curing
Opis:
This paper presents the findings of a study carried out for evaluation of the mechanical behavior of lightweight concrete. Pumice, a rock resulting from cooling of lava, having entrapped air bubbles, has been used as a light- weight coarse aggregate. Evaluation of the mechanical behavior of the Pumice Lightweight Aggregate Concrete (PLWAC) has been carried out in comparison with the conventional concrete while comparing the mechanical properties of the two. Complete replacement of the coarse aggregate by volume had been carried out in the PLWAC. The testing regime consisted of conducting laboratory tests on concrete samples for evaluation of the mechanical properties including compressive strength, tensile stength, workability and dry density. It was concluded from the results that the use of lightweight aggregate resulted in a reduction in workability, as indicated by the slump test. Moreover, the dry density of PLWAC was also reduced by 30% as compared to the conventional concrete. A significant decrease (49%) in the compressive strength of PLWAC as compared to conventional concrete while a minor difference was observed in the tensile strenght of the two (2.9%). Based on the results of this study, it is recommended that PLWAC cannot be used in structures subjected to heavy loading conditions. However, PLWAC has a good potential to be used in low-cost structures with accompanying benefits of weight reduction.
Źródło:
Advances in Science and Technology. Research Journal; 2021, 15, 2; 30-38
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical properties of lightweight expanded clay aggregate (LECA) concrete
Autorzy:
Issa, Atheer S.
Al-Asadi, Ali K.
Powiązania:
https://bibliotekanauki.pl/articles/35562615.pdf
Data publikacji:
2022
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
lightweight concrete
mechanical properties
lightweight expanded clay aggregate
LECA concrete
Opis:
The construction activities are based on structural concrete, which is one of the most commonly used materials. The fundamental aim of using lightweight concrete (LWC) was to reduce the concrete self-weight of the structure parts. As a result, LWC has been used successfully in a variety of installations for several years. In this paper, the mechanical properties of concrete made with lightweight expanded clay aggregate (LECA) as a full replacement for coarse aggregate are studied. The experimental program shows that LECA with a 32 MPa cube compressive strength and an 1,823 kg×m–3 dry density can be used to make structural light-weight aggregate concrete (SLWC). The results show that the reduction in the strength of lightweight aggregate concrete (LWAC) was found to be higher in the concrete with an estimated compressive strength of 32 MPa due to the lower strength of the LWA (expanded clay). According to the test results, the mechanical properties of LWC were greatly improved by adding silica fume (SF). Furthermore, LECA concrete has a splitting tensile strength that is 47% higher than the ASTM C330/C330M-17A minimum requirement. The LECA concrete has a splitting tensile strength to compressive strength ratio of approximately 13%. Additionally, the results demonstrate a 27% difference in the modulus of elasticity between the calculated and tested values.
Źródło:
Scientific Review Engineering and Environmental Sciences; 2022, 31, 3; 161-175
1732-9353
Pojawia się w:
Scientific Review Engineering and Environmental Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lightweight paths in graphs
Autorzy:
Harant, Jochen
Jendrol, Stanislav
Powiązania:
https://bibliotekanauki.pl/articles/255411.pdf
Data publikacji:
2019
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
weighted graph
lightweight path
Opis:
Let k be a positive integer, G be a graph on V(G) containing a path on k vertices, and w be a weight function assigning each vertex v ∈ V(G) a real weight w(y). Upper bounds on the weight [formula] of P are presented, where P is chosen among all paths of G on k vertices with smallest weight.
Źródło:
Opuscula Mathematica; 2019, 39, 6; 829-837
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation and optimization of a new energy vehicle power battery pack structure
Autorzy:
Ruan, Guanqiang
Yu, Changqing
Hu, Xing
Hua, Jing
Powiązania:
https://bibliotekanauki.pl/articles/2055057.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
static
dynamic
modal
lightweight
optimization
Opis:
With the rapid growth in new energy vehicle industry, more and more new energy vehicle battery packs catch fire or even explode due to the internal short circuit. Comparing with traditional vehicles, the new energy vehicles industry should pay more attention to safety of power battery pack structures. The battery pack is an important barrier to protect the internal batteries. A battery pack structure model is imported into ANSYS for structural optimization under sharp acceleration, sharp turn and sharp deceleration turn conditions on the bumpy road. Based on the simulation, the battery pack structure is improved, and suitable materials are determined. Then the collision resistance of the optimized battery pack is verified, and the safety level is greatly improved. While ensuring the safety and reliability of the battery pack structure, it also reduces the weight to satisfy the lightweight design and complies with relevant technical standards.
Źródło:
Journal of Theoretical and Applied Mechanics; 2021, 59, 4; 565--578
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lightweight Security Mechanism to Mitigate Active Attacks in a Mobile Ad-hoc Network
Autorzy:
Ahmed, Uthumansa
Shantha, Fernando
Powiązania:
https://bibliotekanauki.pl/articles/2055257.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Blackhole
lightweight
mechanism
security
simulation
Opis:
Mobile Ad hoc Network (MANET) is a type of Ad hoc network. General properties of MANET open the network to various security threats. Network layer-based Active attacks are widespread and destructive. Available security solutions contain complex calculations. Therefore, the objective of this research is to propose a lightweight security mechanism to enhance the security of data communications between source and destination nodes in a MANET from network layer-based active attack. Blackhole is used as a network layer-based Active attack. The network performance is evaluated using Packet Delivery Ratio (PDR), Average End-to-End Delay (AEED), Throughput, and Simulation Processing Time at Intermediate Nodes (SPTIN). The controller network was used to compare the performance of each network. During the experiment due to the impact of the blackhole attack, compared to the controller network, the PDR was found to be 0.28%, AEED was infinity and Throughput was 0.33%. The performance of the proposed security mechanism was compared with that of the controller network, and the values of PDR, AEED, Throughput, and SPTIN were found to be 98.0825%, 100.9346%, 99.9988%, and 96.5660%, respectively. The data packet delivery ratio was 100.00% compared to that of the controller network. The network that was affected by a blackhole attack showed a higher amount of ADDR than the controller network and the lowest amount of PDR. The network that was affected by the blackhole showed underperformance compared to the controller network. The proposed security mechanism performs well in PDR, AEED, and Throughput compared to the controller network. The AEED and SPTIN values prove that the proposed solution is free from complex calculations. The scope of the solution can be expanded into a lightweight Intruder Detection System to handle different types of security attacks in MANETs.
Źródło:
International Journal of Electronics and Telecommunications; 2022, 68, 1; 145--152
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie betonów lekkich do konstrukcji budowlanych, w szczególności do sprężonych płyt stropowych
Application of lightweight concrete to construction, especially for prestressed flor slabs
Autorzy:
Mieszczak, M.
Powiązania:
https://bibliotekanauki.pl/articles/134748.pdf
Data publikacji:
2016
Wydawca:
ADVSEO
Tematy:
lightweight concrete
elastic modulus
prestress
Opis:
Today's race for innovation and new solutions require from engineers to create new design solutions. One of these innovate solutions could be the using of lightweight concrete for structures subjected to high loads. Lightweight concrete despite smaller and above all worse aggregates have very good mechanical properties. Much less dead weight could lead to significant savings in the amount of reinforcement or massiveness of supports and foundations. The work has shown the possibility of using lightweight concrete for prestressed structures, based on a review of studies of lightweight concrete and numerical calculations.
Źródło:
Technical Issues; 2016, 4; 55-61
2392-3954
Pojawia się w:
Technical Issues
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Decreasing of movable masses in valve timing using roller tappet
Autorzy:
Warda, B.
Siczek, K.
Powiązania:
https://bibliotekanauki.pl/articles/247946.pdf
Data publikacji:
2012
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
valve timing
lightweight camshaft
roller tappet
Opis:
The method for reduction of valve timing movable masses, by the use of composite cams for camshaft, which mate with roller tappet, is presented. It has been carried out an analysis of stresses under the surface of the cam using the methodology and computer programs allowing the synthesis and analysis of the cam mechanism, and to estimate the fatigue life, as well as using the finite element method. Mating roller tappets with a light camshaft, forged from TiAl alloy, can be done if the camshaft has steel caps set under the pressure on the surfaces their cams. The problem, however, is the formation of high stress in the Bielaiev point, when a roller tappet mates with segment cam. Because of the certainty for the cap fixing, it is assumed that the depth for the Bielaiev point should not exceed half the thickness of the cap. The stress analysis shows, that exceeding of the material yield strength is controlled by the interference value between the cam and its cap and by the apex radius of the cam. Effect of contact stress is at least an order of magnitude smaller. The maximum depth of the Bielaiev point does not exceed 0.09 mm, which is about half the thickness of the proposed cap. There is a need not for too small radii between the cam and the apical cap. Optimal selection of proper geometry of the cam will be easier after a proper modification of the program used for the synthesis and analysis of the cam mechanism, such that it is possible to ask any operational surface of the cam profile.
Źródło:
Journal of KONES; 2012, 19, 1; 473-481
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lightweight cryptographic algorithm based on trigonometry, dedicated on encryption of short messages
Autorzy:
Maleszewski, Wiesław
Powiązania:
https://bibliotekanauki.pl/articles/23313488.pdf
Data publikacji:
2022
Wydawca:
Politechnika Gdańska
Tematy:
IoT cryptography
lightweight cryptography
flexible cryptography
Opis:
The IoT technology is currently used in many areas and marked by growing popularity. On the one hand, the IoT makes our lives easier, on the other hand, it presents challenges in terms of security and privacy protection. An IoT infrastructure is characterized by a high level of threats due to, inter alia, numerous technical barriers that make it difficult to use conventional methods to protect information. The aim of this paper is to present a symmetric coding algorithm based on algebraic groups generated by specific trigonometric curves. The algorithm is dedicated to short data sequences transmitted by devices with limited computing power.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2022, 26, 3
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wpływ składu mieszanki i wyjściowego zawilgocenia kruszywa lekkiego na sorpcyjność kapilarną betonu keramzytowego
Influence of mix composition and initial moistness of lightweight aggregate on capillary sorption of expanded clay aggregate concrete
Autorzy:
Garbalińska, H.
Narodowska, K.
Powiązania:
https://bibliotekanauki.pl/articles/105250.pdf
Data publikacji:
2017
Wydawca:
Politechnika Rzeszowska im. Ignacego Łukasiewicza. Oficyna Wydawnicza
Tematy:
keramzytobeton
kapilarność
współczynnik sorpcji wody
wilgotność
kruszywo lekkie
lightweight concrete
capillarity
water sorption coefficient
moisture of lightweight
Opis:
W artykule opisano badania kapilarności przeprowadzone na grupie sześciu betonów keramzytowych, wykonanych na bazie tych samych składników. W każdym przypadku użyto tego samego cementu portlandzkiego 42,5 R, wody wodociągowej pitnej oraz kruszywa keramzytowego frakcji 4 – 8 mm oraz piasku kwarcowego frakcji 0 – 2 mm. Poszczególne receptury różniły się po pierwsze stanem wilgotnościowym kruszywa grubego, które wprowadzane było do mieszanki jako kruszywo suche (S), powietrzno-suche (P) oraz w pełni nasycone wodą (N). Po drugie mieszanki różniły się objętościowym udziałem kruszywa lekkiego i zaprawy cementowej. Przyjęto proporcje zaprawa cementowa : kruszywo keramzytowe na poziomie 1:1 oraz 3:2. W rezultacie badaniom poddano 6 mieszanek umownie oznaczonych jako S 1:1, P 1:1, N 1:1 oraz S 3:2, P 3:2, N 3:2. Wykazano, że betony te charakteryzują się wyraźnie różnym tempem podciągania kapilarnego, a tym samym różnymi wartościami współczynników sorpcji kapilarnej A. Najlepszymi parametrami odznaczały się betony wykonane na kruszywie suchym o stosunku zaprawa:kruszywo 1:1. Wykazały one najniższą wartość współczynnika sorpcji wynoszącą A = 0,9 kg/(m2h). Ten rodzaj betonu będzie najefektywniej blokował wnikanie wody w beton i w konsekwencji będzie odznaczał się najwyższą odpornością na działanie substancji korozyjnych wprowadzanych z wodą oraz najwyższą mrozoodpornością. Najgorszymi parametrami charakteryzowały się keramzytobetony o większym udziale objętościowym zaprawy cementowej, tj. o proporcjach zaprawa:kruszywo keramzytowe 3:2. Przy czym w przypadku kruszywa nasyconego wodą (N) i ziarnach wysuszonych na powierzchni (P) uzyskano współczynniki A wyższe odpowiednio 2,52,8 razy w stosunku do receptury S 1:1.
This paper presents the results of capillary porosity tests carried out using six expanded clay aggregate concretes, made from the same ingredients. Each aggregate was manufactured with the same type of Portland cement 42.5 R, potable mains water, expanded clay aggregate (4–8mm), and quartz sand (0–2mm). The effect of coarse aggregate humidity on the mixture was examined using dry (S), air-dry (P) and fully saturated (N) aggregates. Additionally, the mixtures had different volume ratios of lightweight aggregate and cement mortar. Ratios of 1:1 and 3:2 of cement mortar and expanded clay aggregate were used. Consequently, tests were carried out using 6 mixture types labelled S 1:1, P 1:1, N 1:1 and S 3:2, P 3:2, N 3:2. The results confirmed that these concretes had significantly different rates of capillarity and water absorption coefficients due to capillarity. The best results were obtained from concretes made using the dry aggregate with a 1:1 ratio of mortar and aggregate. This concrete had the lowest coefficient of A = 0.882 kg/(m2h). This type of concrete should most efficiently prevent water absorption and, as a consequence, ensure the highest resistance to corrosive substances carried by water, as well as the highest freeze-thaw resistance. The least favourable were expanded clay aggregate concretes with a large volume of mortar, namely a 3:2 ratio of cement mortar and expanded clay aggregate. For aggregates saturated with water (N) and aggregate particles dried on the surface (P), the A coefficient was 2.5 and 2.8 times higher with respect to the S 3:2 mixture.
Źródło:
Czasopismo Inżynierii Lądowej, Środowiska i Architektury; 2017, 64, 4/I; 277-284
2300-5130
2300-8903
Pojawia się w:
Czasopismo Inżynierii Lądowej, Środowiska i Architektury
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental Determination of Optimum Mixture Design of Lightweight Concrete
Eksperymentalne określanie optymalnego projektu betonu lekkiego
Autorzy:
Katzer, Jacek
Kobaka, Janusz
Powiązania:
https://bibliotekanauki.pl/articles/1811742.pdf
Data publikacji:
2020
Wydawca:
Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:
lightweight aggregate
expanded clay granules
lightweight concrete
properties
research testing
kruszywo lekkie
keramzyt
beton lekki
właściwości
badania
Opis:
This paper describes the mixture design of lightweight concrete. The authors proposed lightweight concrete based solely on expanded clay aggregate. Commercially available expanded clay granules (used as coarse aggregate) were supplemented with crushed expanded clay granules (which played the role of fine aggregate). The created mixes were differentiated by particle size distribution of lightweight aggregate and the amount of used cement. Properties of both fresh concrete mixes and hardened composites were of interest. The tested properties were as follows: consistency, density, compression strength, splitting tensile strength, dynamic modulus of elasticity, flexural strength, shear strength and abrasion resistance. Experimental results have shown some satisfactory mechanical characteristics of concretes in question.
Artykuł opisuje projektowanie betonu lekkiego. Autorzy zaproponowali projekt betonu lekkiego wykonanego wyłącznie na bazie kruszywa keramzytowego. Dostępne na rynku kruszywo keramzytowe (użyte jako kruszywo grube) uzupełniono pokruszonym kruszywem tego samego rodzaju (pełniącego rolę kruszywa drobnego). Utworzone mieszanki kruszyw różniły się uziarnieniem kruszyw i zawartością cementu. Zbadano właściwości zarówno świeżej mieszanki betonowej jak i stwardniałego betonu takie jak: konsystencja, gęstość, wytrzymałość na ściskanie, wytrzymałość na rozciąganie przy rozłupywaniu, dynamiczny moduł sprężystości, wytrzymałość na rozciąganie przy zginaniu, wytrzymałość na ścinanie i odporność na ścieranie. Wyniki badań eksperymentalnych wykazały zadowalającą charakterystykę zbadanych właściwości.
Źródło:
Rocznik Ochrona Środowiska; 2020, Tom 22, cz. 2; 781-790
1506-218X
Pojawia się w:
Rocznik Ochrona Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photovoltaic modules with a modified ETFE foil for BIPV applications
Autorzy:
Drabczyk, Kazimierz
Kulesza-Matlak, Grażyna
Sobik, Piotr
Jeremiasz, Olgierd
Powiązania:
https://bibliotekanauki.pl/articles/27315689.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
photovoltaics
lightweight photovoltaic module
building integrated photovoltaics
Opis:
This article introduces a laboratory-scale concept and research on photovoltaic (PV) modules designed for building integrated photovoltaics (BIPV) market, with enhanced architectural aesthetics and no protective glass. The proposed concept involves replacing a typical glass protective and load-bearing element of PV modules with an ethylene tetrafluoroethylene (ETFE) foil while using an aluminium sheet as a load-bearing element in the system. To further enhance the visual appeal of the solution, special modifications were proposed to the geometry of the front security foil. To confirm the feasibility of the proposed concept for mass production, critical tests were conducted on the material system and the process of modifying the surface of the ETFE foil. These tests included evaluating adhesion strength between layers, optical transmission coefficients, and electrical parameters of the developed PV modules. Additionally, the effect of the ETFE film modification on the formation of micro-cracks in solar cells was also investigated.
Źródło:
Opto-Electronics Review; 2023, 31, 4; art. no. e147914
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimizing circular polarization within a beam of patch antenna elements
Autorzy:
Hornik, M.
Hornik, P.
Guzda, D.
Kabacik, P.
Powiązania:
https://bibliotekanauki.pl/articles/307578.pdf
Data publikacji:
2007
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
lightweight antennas
circularly polarized antennas
microstrip antennas
Opis:
The paper presents the results of an investigation into patch antenna elements that would be capable of pro- viding good circular polarization not only in the broadside direction, but also over a wide range of elevation angles.
Źródło:
Journal of Telecommunications and Information Technology; 2007, 1; 18-22
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Al/Cu Weight Fraction on the Mechanical and Electrical Properties of Al-Cu Conductors for Overhead Transmission Lines
Autorzy:
Han, Deokhyun
Kim, Geon-Hong
Kim, Jaesung
Ahn, Byungmin
Powiązania:
https://bibliotekanauki.pl/articles/356537.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
transmission line
aluminum
lightweight
extrusion
intermetallic
tensile
Opis:
In the past few years, overhead copper transmission lines have been replaced by lightweight aluminum transmission lines to minimize the cost and prevent the sagging of heavier copper transmission lines. High strength aluminum alloys are used as the core of the overhead transmission lines because of the low strength of the conductor line. However, alloying copper with aluminum causes a reduction in electrical conductivity due to the solid solution of each component. Therefore, in this study, the authors attempt to study the effect of various Al/Cu ratios (9:1, 7:3, 5:5) to obtain a high strength Al-Cu alloy without a significant loss in its conductivity through powder metallurgy. Low-temperature extrusion of Al/Cu powder was done at 350ºC to minimize the alloying reactions. The as-extruded microstructure was analyzed and various phases (Cu9Al4, CuAl2) were determined. The tensile strength and electrical conductivity of different mixing ratios of Al and Cu powders were studied. The results suggest that the tensile strength of samples is improved considerably while the conductivity falls slightly but lies within the limits of applications.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 3; 1019-1022
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lightweight Geopolymer Made of Pumice with Various Aluminum Powder Ratios
Autorzy:
Çetınkaya, S.
Kurt, H.
Kütük, N.
Powiązania:
https://bibliotekanauki.pl/articles/1031665.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
lightweight geopolymers
pumice
compressive strength
aluminum powder
Opis:
In this work, a lightweight geopolymer was prepared using various mass proportions of extra fine aluminum powder and pumice stone that is durable to heat and sound-proof. The effect of NaOH concentration, aluminum mass ratio, the curing temperature and the curing time of the mixture on the compressive strength of the lightweight geopolymers were examined. The concentration of NaOH was found to be 2 M while the mass proportion of Na₂SiO₃/NaOH was found to be 17.5 on the lightweight geopolymers that have the highest compressive strength and the best workability in experiments. The lightweight geopolymer attained the best compressive strength with 1.6 MPa on the 28th day of curing process at 40°C. The mass proportion of aluminum used in the lightweight geopolymer was 2.5% as the density of the lightweight geopolymer obtained was 0.9 g/cm³. Their properties were examined using the Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 544-545
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effects of Additives to Lightweight Aggregate on the Mechanical Properties of Structural Lightweight Aggregate Concrete
Autorzy:
Khoshvatan, Mehdi
Pauraminia, Majid
Powiązania:
https://bibliotekanauki.pl/articles/1943256.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
lightweight concrete
perlite
lightweight aggregate
pumice
leca
mechanical properties
beton lekki
perlit
kruszywo lekkie
pumeks
keramzyt
właściwości mechaniczne
Opis:
In the paper, the effects of different percentages of additives (perlite, LECA, pumice) on the mechanical properties of structural lightweight aggregate concrete were tested and evaluated. For the research, 14 mixing designs with different amounts of aggregate, water, and cement were made. Experimental results showed that the specific gravity of lightweight structural concrete made from a mixture of LECA, pumice, and perlite aggregates could be 25-30% lighter than conventional concrete. Lightweight structural concrete with a standard specific gravity can be achieved by using a combination of light LECA with perlite lightweight aggregates (LA) and pumice with perlite in concrete. The results indicated that LECA lightweight aggregates show more effective behavior in the concrete sample. Also, the amount of cement had a direct effect on increasing the strength regardless of the composition of LAs. The amount of cement causes compressive strength to increase. Furthermore, the stability of different experimental models increased from 156 to 345 kg m3 while increasing the amount of cement from 300 to 400 kg m3 in the mixing designs of LECA and perlite for W/C ratios of 0.3, 0.35, and 0.4. For a fixed amount of cement equal to 300 kg, the compressive strength is reduced by 4% by changing the water to cement ratio from 0.5 to 0.4. The compression ratios of strength for 7 to 28 days obtained in this study for lightweight concrete were between 0.67-0.8. rate of tensile strength to compressive strength of ordinary concretes, which is approximately 10, this ratio is about 13.5 to-17.8 in selected and optimal lightweight concretes in this research, which can be considered good indirect tensile strength for structural lightweight concretes.
Źródło:
Civil and Environmental Engineering Reports; 2021, 31, 1; 139--160
2080-5187
2450-8594
Pojawia się w:
Civil and Environmental Engineering Reports
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Właściwości fizyczne i mechaniczne keramzytu otrzymanego z dodatkiem glaukonitu
Physical and mechanical properties keramsite obtained with added glauconite
Autorzy:
Franus, M.
Powiązania:
https://bibliotekanauki.pl/articles/391147.pdf
Data publikacji:
2012
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
keramzyt
glaukonit
cechy fizyczne i mechaniczne keramzytu
lightweight of aggregate
glauconite
physical and mechanical properties lightweight of aggregates
Opis:
W pracy przedstawiono ocenę właściwości fizycznych i mechanicznych keramzytu otrzymanego z dodatkiem minerału ilastego – glaukonitu oraz gliny ze złoża „Budy Mszczonowskie”. Kruszywo otrzymano metodą plastyczną przez wypalenie w temperaturze 1170°C. Oceny parametrów fizycznych dokonano na podstawie parametrów takich jak gęstość właściwa, gęstość objętościowa i nasypowa, szczelność, porowatość, nasiąkliwość wodą. Badania cech mechanicznych przeprowadzono na podstawie mrozoodporności kruszywa, wytrzymałości na miażdżenie, ścieralności w bębnie Los Angeles. Ponadto oznaczono związki barwiące w kruszywie. Wykorzystanie glaukonitu do kruszywa korzystnie wpływa na teksturę spieku powodując powstawanie szklistej błony na powierzchni granul i podwyższając ich porowatość. Badane właściwości wskazują, że otrzymane kruszywo keramzytowe z dodatkiem glaukonitu spełnia podstawowe wymagania stawiane wobec materiałów stosowanych w budownictwie.
This paper presents the assessment of the physical and mechanical properties lightweight of aggregate obtained from the addition of expanded clay mineral clay – glauconite and clay from the bed, “Buda Mszczonowska”. Crushed plastic was prepared by firing at a temperature of over 1170 ° C. Evaluation of physical parameters was based on parameters such as density, bulk density and bulk density, tightness, porosity, water absorption. The study of mechanical properties was carried out on the basis of aggregate hardiness, resistance to crushing, abrasion in the drum Los Angeles. In addition, the compounds were determined in the aggregate coloring. Use glauconite in the lightweight of aggregate is beneficial for the texture of the sinter resulting in the formation of a glassy layer on the surface of the granules, and by increasing their porosity. Investigated the properties indicate that the resulting lightweight of aggregate with glauconite meets the basic requirements for materials used in construction
Źródło:
Budownictwo i Architektura; 2012, 10, 1; 5-14
1899-0665
Pojawia się w:
Budownictwo i Architektura
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of the pre-wetting of expanded clay aggregate on the freeze-thaw resistance of the expanded clay aggregate concrete
Autorzy:
Musiał, Michał Piotr
Grzymski, Filip
Trapko, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/1845171.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
lightweight concrete
freeze-thaw resistance
aggregate pre-wetting
Opis:
This paper presents experimental research on expanded clay aggregate concrete. The aim of the investigations was to determine if the pre-wetting of expanded clay aggregate has an effect on the freeze-thaw durability of the expanded clay aggregate concrete. Five concrete series based on the same concrete mix design were made and tested. The degree of pre-wetting of the aggregate was varied: dry aggregate was used in the first series, aggregate with a moisture content of 10% was used in series IA and IB and aggregate with a moisture content of 25% was used in series IIA and IIB. Also the approach to the production process was varied: in series A the water contained in the aggregate was taken into account in the global water-cement ratio (consequently a reduced amount of water was added to the mix), whereas in series B the nominal amount of water was added to the mix (as in the case of dry aggregate). The freeze-thaw resistance criterion was based on the assessment of the decrease of compressive strength and increase in weight loss after exposure to freeze-thaw cycles. The expanded clay aggregate concrete’s strength and mass decrements caused by freeze-thaw cycling were used as the measure of its freeze-thaw resistance. The investigations have shown that the pre-wetting of expanded clay aggregate has an effect on the freeze-thaw durability of the expanded clay aggregate concrete. The differences of concrete compressive strength decrease related to freezethaw durability may be 2 to 5 times greater when inadequate method of calculating mixing water for concrete is used.
Źródło:
Studia Geotechnica et Mechanica; 2021, 43, 2; 65-73
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shear performance of reinforced self-compacting concrete beams incorporating steel and polypropylene fibers
Autorzy:
Alkhattat, Saja S.
Al-Ramahee, Munaf A.
Powiązania:
https://bibliotekanauki.pl/articles/35550882.pdf
Data publikacji:
2021
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
steel fiber
lightweight concrete
polypropylene fibre
shear strength
Opis:
The impact of steel and polypropylene fibers on the performance of lightweight self-compacting concrete (LWSCC) beams was investigated in this study. Seven beams with various parameters were cast and tested. Partial (50%) and full (100%) replacement of coarse aggregate with lightweight aggregate expanded clay (LECA) were considered. In addition, a 1% volumetric ratio of steel or hybrid (steel and polypropylene) fiber was added to LWSCC beams to study their effect on the shear performance. The LWSCC beams had a decrease in ultimate load and stiffness of 23 and 30% for partial and full replacement, respectively when compared to normal weight beam. The addition of steel fiber improved the efficiency of LWSCC beams in terms of crack formation, failure mode, crack width, and ultimate load, as well as changed the failure mode from shear to flexure. The ultimate load for hybrid LWSCC was increased by around 6% for a partial replacement and 13% for full replacement as compared to beams without fibers. However, hybrid beams had a larger bearing capacity, little more cracks with smaller size, and ductile failure.
Źródło:
Scientific Review Engineering and Environmental Sciences; 2021, 30, 4; 537-551
1732-9353
Pojawia się w:
Scientific Review Engineering and Environmental Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Betony lekkie jako elementy obudowy wstępnej szybów drążonych w sztucznie zamrożonym górotworze
Light Weight Aggregate Concretes as structural element of the preliminary lining of shaft driven in artificially frozen rock mass
Autorzy:
Hydzik, J.
Czaja, P.
Powiązania:
https://bibliotekanauki.pl/articles/349922.pdf
Data publikacji:
2007
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
obudowa szybu
beton lekki
shaft lining
lightweight aggregate concrete
Opis:
Zastosowanie betonów lekkich jako elementów izolacyjnych oraz izolacyjno-konstrukcyjnych na obudowę wstępną szybu w istotny sposób zmienia warunki wymiany ciepła pomiędzy zamrożonym górotworem a wnętrzem szybu. W artykule przedstawiono wyniki badań laboratoryjnych, w których określono możliwość uzyskania tych betonów ze szczególnym uwzględnieniem wiązania oraz twardnienia w bezpośrednim kontakcie z zamrożonym górotworem.
The application of Light Weight Aggregate Concrete (LWAC) as heat insulating and structural element for the preliminary lining of shaft fundamentally change the conditions of interchange heat between frozen rock mass and inside of shaft. This paper presents results of the laboratory tests in which the possibility of obtaining concretes especially with allow for binding and hardening in direct contact with frozen rock mass was specified.
Źródło:
Górnictwo i Geoinżynieria; 2007, 31, 3; 191-198
1732-6702
Pojawia się w:
Górnictwo i Geoinżynieria
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deep learning-based fault diagnosis for marine centrifugal fan
Autorzy:
Li, Congyue
Hu, Yihuai
Jiang, Jiawei
Yan, Guohua
Powiązania:
https://bibliotekanauki.pl/articles/32917700.pdf
Data publikacji:
2023
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
CEEMDAN
fault diagnosis
lightweight neural network
marine centrifugal fan
Opis:
Marine centrifugal fans usually work in harsh environments. Their vibration signals are non-linear. The traditional fault diagnosis methods of fans require much calculation and have low operating efficiency. Only shallow fault features can be extracted. As a result, the diagnosis accuracy is not high. It is difficult to realize the end-to-end fault diagnosis. Combining the Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) and lightweight neural network, a fault classification method is proposed. First, the CEEMDAN can decompose the vibration signal into several intrinsic modal functions (IMF). Then, the original signals can be transformed into 2-D images through pseudocolour coding of the IMFs. Finally, they are fed into the lightweight neural network for fault diagnosis. By embedding a convolutional block attention module (CBAM), the ability of the network to extract critical feature information is improved. The results show that the proposed method can adaptively extract the fault characteristics of a marine centrifugal fan. While the model is lightweight, the overall diagnostic accuracy can reach 99.3%. As exploratory basic research, this method can provide a reference for intelligent fault diagnosis systems on ships.
Źródło:
Polish Maritime Research; 2023, 1; 112-120
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Employment of recycled wood waste in lightweight concrete production
Autorzy:
Alharishawi, Salam Salman Chiad
Abd, Haitham Jameel
Abass, Suha Rasheed
Powiązania:
https://bibliotekanauki.pl/articles/1849785.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
beton lekki
kruszywo lekkie
trociny
włókno drzewne
odpad drzewny
beton zwykły
lightweight concrete
lightweight aggregate
sawdust
wood fiber
wood waste
normal concrete
Opis:
The by-products of wood sawdust and wood fiber are considered to be waste material. It is utilized in the construction of buildings in the form of sawdust concrete or wood fiber concrete. It is used to make lightweight concrete and possesses heat transfer of a long duration. In this study, wood concrete was made at eleven different mix proportions of cement to wood waste by weight, to produce a lightweight concrete aggregate that has the density 1508-2122 kg/m3. The experimental work consists of 330 concrete specimens as 99 cubes (150 * 150 * 150) mm, 165 cylinders (150 * 300) mm, 33 prisms (50 * 100 * 200) mm, and 33 prisms (100 * 100 * 500) mm. Mechanical and thermal properties such as stiffness, workability, compressive strength, static elasticity modulus, flexural forces, splitting tensile strength and density were examined in the specimens after 28 days of 20 oC curing. Also, compressive strength was investigated at 7 and 14 days of curing at 20 oC. The basic observation of the results shows the values with the limitations of ACI and ASTM. Moreover, it is the perfect way to reduce solid wood waste and produce lightweight concrete to be used in industrial construction. It was found that with the increase in the quantity of wood waste, the strength decreased; however, in terms of workability and concrete with a higher quantity of wood waste held very well. Lightweight concrete aggregate is around 25 percent lighter in dead load than standard concrete. Given all the physical and mechanical properties, the study finds that wood concrete can be used in the construction of buildings.
Źródło:
Archives of Civil Engineering; 2020, 66, 4; 675-688
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wpływ poziomu wstępnego nawilżenia kruszywa popiołoporytowego na mrozoodporność konstrukcyjnych betonów lekkich
The influence of initial moisture content of sintered fly ash aggregate on freezing and thawing resistance of structural lightweight concrete
Autorzy:
Domagała, L.
Powiązania:
https://bibliotekanauki.pl/articles/160417.pdf
Data publikacji:
2014
Wydawca:
Polski Związek Inżynierów i Techników Budownictwa
Tematy:
kruszywo lekkie
kruszywo popiołoporytowe
zawartość wody
beton lekki
mrozoodporność
lightweight aggregate
sintered fly ash aggregate
water content
lightweight concrete
frost resistance
Opis:
W artykule omówiono zagadnienie mrozoodporności konstrukcyjnych betonów lekkich z kruszywem popiołoporytowym, ze szczególnym uwzględnieniem wpływu jego wstępnej wilgotności. Badaniom na cykliczne zamrażanie i rozmrażanie poddano betony o zróżnicowanych charakterystykach wytrzymałościowych, wykonane na kruszywie lekkim i zaprawach cementowych z piaskiem naturalnym. Uzyskane wyniki badań wskazują, że pomimo zastosowania kruszywa popiołoporytowego o znacznej nasiąkliwości, istnieje możliwość wykonania konstrukcyjnych betonów lekkich o wysokiej mrozoodporności, pod warunkiem ograniczenia poziomu wstępnego nawilżenia kruszywa lekkiego przy ewentualnej redukcji współczynnika wodno-cementowego.
The problem of frost resistance of structural lightweight concrete with sintered fly ash aggregate, with special consideration of its initial moisture content, is presented in this paper. Concretes made of cement mortars with normal-weight sand and lightweight aggregates of various strength levels were subjected to cyclic freezing and thawing. Obtained results showed, that in spite of application of sintered fly ash aggregate of high water absorption, it was possible to make structural lightweight concrete of high frost resistance. To achieve this aim it is necessary to limit initial aggregate moisture at alternatively appropriate reduction of water-cement ratio.
Źródło:
Przegląd Budowlany; 2014, R. 85, nr 5, 5; 18-21
0033-2038
Pojawia się w:
Przegląd Budowlany
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Researches on friction force between valve made of tial and its guide made of phosphorous bronze
Autorzy:
Siczek, K.
Powiązania:
https://bibliotekanauki.pl/articles/243568.pdf
Data publikacji:
2013
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
valvetrain
lightweight valve
friction force
TiAl alloy
phosphorous bronze
Opis:
A lightweight valve can be one made of steel but with a drilled stem. Another one can be made of TiAl alloys and its stem can be full or drilled. Lightweight valve can be also ceramic one made of Si3N4. Such valves can mate with guides made of cast iron or of phosphorous bronze in varying conditions in their common contact zone. The aim of researches has been to measure friction force in contact zone between valve stem made of TiAl alloy and its guide made of phosphorous bronze, in the absence of oil. The conditions of room temperature and of the atmosphere pressure have been used during experiment. Mentioned researches have been provided in tester, which design has been presented in the article. The loading of contact zone has varied periodically during serie. The displacement and acceleration of valve and the force during its impact into seat insert have been measured during tests. Additionally the sound level has been measured, either. Tests have been provided for different frequency of driving force. Obtained results of researches has been shown in the article. In all cases the measured sound level have been equal 94 dBA, when sound level of laboratory environment has been equal 40 dBA. Values for coefficient of friction between valve stem and its guide can change from 0.12 to 0.16 and decrease almost linearly with increasing of loading frequency. Values of dry friction coefficient between valve stem made of TiAl alloy and coated by chrome and its guide made of phosphorous bronze can be smaller up to 17% than values obtained in case of valve stem coated by nc-WC/a-C:H mating with a guide made of cast iron.
Źródło:
Journal of KONES; 2013, 20, 1; 295-301
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improving security of lightweith SHA-3 against preimage attacks
Autorzy:
Serhii, O.
Kotulski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/227343.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hash function
SHA-3
Keccak
preimage attack
lightweight cryptography
Opis:
In this article we describe the SHA-3 algorithm and its internal permutation in which potential weaknesses are hidden. The hash algorithm can be used for different purposes, such as pseudo-random bit sequences generator, key wrapping or one pass authentication, especially in weak devices (WSN, IoT, etc.). Analysis of the function showed that successful preimage attacks are possible for low round hashes, protection from which only works with increasing the number of rounds inside the function. When the hash function is used for building lightweight applications, it is necessary to apply a small number of rounds, which requires additional security measures. This article proposes a variant improved hash function protecting against preimage attacks, which occur on SHA-3. We suggest using an additional external randomness sources obtained from a lightweight PRNG or from application of the source data permutation.
Źródło:
International Journal of Electronics and Telecommunications; 2018, 64, 2; 159-166
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigating the Effect of Sisal Fibre Content on Durability Properties of Lightweight Foamed Concrete
Autorzy:
Mydin, Md Azree Othuman
Powiązania:
https://bibliotekanauki.pl/articles/2172354.pdf
Data publikacji:
2022
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
porosity
lightweight foamed concrete
sisal fibre
shrinkage
water absorption
Opis:
Lightweight foamed concrete is greatly permeable, and its durability performance reduce with rising in the number of voids. In turn to improve its durability properties, the solid matrix of lightweight foamed concrete can be adjusted by incorporating several plant-based fibres. The effect of sisal fibre in lightweight foamed concrete was not explored before in the current body of knowledge. Therefore, there is some uncertainty considering the mechanism by which and the extent to which the sisal fibre may impact lightweight foamed concrete durability properties. Thus, this laboratory study concentrates on distinguishing the potential employment of sisal fibre into lightweight foamed concrete. This investigation aims to establish the durability performance of lightweight foamed concrete with the presence of sisal fibre. Densities of 800 and 1600 kg/m3 were made and assesed. Different weight fractions of sisal fibre of 0.2%, 0.4%,0.6% and 0.8% were utilized. There were four durability perfomance of lightweight foamed concrete were evaluated such as shrinkage, ultrasonic pulse velocity (UPV), porosity and water absorption capacity. The experimental results had indicated that the addition of 0.6% of sisal fibre gave the optimum results for the durability properties. At 0.6% weight fraction of sisal fibre, the fibres reached maximum compaction in the cement matrix, which stemmed in exceptional mix regularity. Further than 0.6% inclusion of sisal fibre, accumulation and non-regularity scattering of fibres was detected, which led to reduction in entire parameters assessed.
Źródło:
Advances in Science and Technology. Research Journal; 2022, 16, 2; 141--149
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-25 z 141

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