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1

Optimizing Fused Deposition Modelling Process Parameters for Medical Grade Polymethylmethacrylate Flexural Strength

Obaeed Nareen Hafidh, Hamdan Wisam K.

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 1

349--359

EN

The production of functional parts, including those employed by the biomedical industry has been achieved a promising candidate in Fused Deposition Modelling (FDM). The essential properties of these biomedical parts which manufactured by additive manufacturing as compared to some other conventional manufacturing processes depend on structural and process parameters rather than material properties alone. Regarding to the evaluation the flexural strength of medical-grade, Polymethylmethacrylate PMMA has been received relatively very little investigation to date. PMMA is a biocompatible filament that be used in manufacturing of patient-specific implants such as dental prosthesis and orthopaedic implants. The proposed work explores the effect of three process parameters that vary with respect of three levels on the flexural strength. These levels can be specified by layer height (120, 200, 280 µm), infill density (40, 65, 90 %) and skewing angle (0º, 45º, 90º) on the flexural strength of medical-grade PMMA. Maximum and minimum flexural strength that be obtained in this work about (93 and 57 MPa) respectively. The analysis of variance (ANOVA) results shows that the most effective factor is the layer height followed by infill density. The flexural strength rises significantly with decreases layer height and the skewing angle is in zero direction. The process parameters have been optimized through utilizing of genetic algorithms. The optimal results that emerged based on genetic algorithm technique are approximately (276 μm) as layer height, (46 %) infill density and skewing angle (89 º) which maximize the flexural strength to (97 MPa) at crossover for ten generation.

2

Effect of thermoplastic waste from production on the strength of cement mortars

Pietrzak Alina

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2023

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nr 75 (147)

42--48

EN

This paper presents study results on the effect of the addition of polymeric waste on selected mechanical properties (flexural and compressive strength) of cementitious composites with a special emphasis on cement mortars. This research focuses on cement mortars, commonly used in construction applications such as seaports and quays. Here, post-production waste from the production of automobile floor mats is ground to a fraction of 0–2 mm and used in the amounts of 5%, 7.5%, and 10% by weight of cement as an additive or substitute for sand. All the presented tests are conducted in accordance with PN-EN 197-1. The purpose of these tests is to determine the possibility of using thermoplastic waste as an aggregate substitute or additive in cement mortars. The conducted research confirmed the possibility of using the mentioned waste in cement mortar production technology in the amount of 5% as a substitute for sand.

3

Paper-sawdust composites: fabrication and comparison in terms of heat transfer and strength properties

Robert Ubong Williams, Ekong Sylvester Andrew, Akpan Samuel Sunday, Etuk Sunday Edet, Inyang Namdie Joseph, Agbasi Okechukwu Ebuka

Structure and Environment

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2023

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Vol. 15, no. 1

38--49

EN

This study was designed to examine the feasibility of recycling cassava effluent, sawdust, and unused paper products to enhance their utilization for beneficial purpose. Waste newspaper paste (WNP), Waste writing-paper paste (WWP), and Waste carton paper paste (WCP) were prepared and then used separately to similarly fabricate composite panels with Sawdust particle (SDP) proportioned at 0%, 25%, 50%, 75%, and 100% by weight. The binder used was cassava starch slurry prepared from the effluent. Bulk density, water absorption, thermal conductivity, specific heat capacity, thermal diffusivity, nailability, and flexural strength were determined for the developed samples. From the results obtained, the samples were found to be light-weight and their thermal insulation performance improved with increasing proportions of the SDP. Though samples containing the WCP exhibited the best satisfactory performance, it was found that all the studied samples could perform more effectively and efficiently as ceilings compared to some of those reported in the literature. From scientific-economic viewpoint, valorizing the above-mentioned wastes as described in this paper could help to protect the environment and also yield value-added insulation ceilings for enhancement of sustainable building construction especially in tropical areas.

PL

Celem pracy było określenie możliwości recyklingu ścieków z manioku, trocin i odpadowych materiałów papierniczych w celu ich szerszego wykorzystania. Nitki z makulatury gazetowej (WNP), nitki z makulatury z papieru do pisania (WWP) i nitki z makulatury z kartonu (WCP) zostały przygotowane, a następnie użyte osobno do wytworzenia paneli kompozytowych z dodatkiem trocin (SDP) przy udziale masowym 0%, 25%, 50 %, 75% i 100%. Zastosowanym spoiwem była przygotowana z odcieku zawiesina skrobi z manioku. Dla przygotowanych próbek określono gęstość nasypową, nasiąkliwość, przewodność cieplną, ciepło właściwe, dyfuzyjność cieplną, zdolność do wbijania gwoździ i wytrzymałość na zginanie. Na podstawie uzyskanych wyników stwierdzono, że próbki miały małą gęstość objętościową, a ich właściwości termoizolacyjne poprawiały się wraz ze wzrostem udziału trocin (SDP). Chociaż próbki zawierające WCP wykazywały najlepsze właściwości, stwierdzono, że z wszystkich badanych próbek można wytworzyć sufity o lepszych właściwościach w porównaniu z podobnymi opisanymi w literaturze. Z naukowo-ekonomicznego punktu widzenia zastosowanie wyżej wymienionych odpadów, jak opisano w tym artykule, może pomóc w ochronie środowiska, a także w uzyskaniu bardziej ciepłochronnych stropów, a co za tym idzie przyczyni się do rozwoju bardziej zrównoważonego budownictwa, zwłaszcza w obszarach tropikalnych.

4

Effects of incorporating granite powder in the mechanical properties of concrete

Muñoz Pérez Socrates Pedro, Atoche Zamora Jorge Jr.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2023

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Vol. 32, No. 1

18--33

EN

This study analyzes the effects of the incorporation of the granite powder (GP) as a partial replacement of the sand in the concrete in percentages of 10%, 15%, 20% and 30% to carry out a mix design of 210 kg·cm–2. Seeking to find an optimal proportion to increase its mechanical properties where the geotechnical characteristics of the aggregates were identified, workability, temperature, beams and concrete specimens were elaborated. The results of bending and compression tests were compared after 7, 14 and 28 days from setting between the standard concrete and the concrete incorporated with the GP. It is concluded that the optimal result was at 20% GP with 268.6 kg·cm–2, where the compressive strength increases by 13%, while its flexural property rupture modulus of 35 kg·cm–2 and workability are in an optimal range according to the stipulated parameters, thus allowing an important application for this waste in the construction industry, therefore contributing to recycling, environmental quality and the development of the usage of new materials.

5

Ocena wpływu ekstremalnych temperatur utwardzania wyrobów do konstrukcyjnego łączenia materiałów na ich wybrane właściwości użytkowe

Wojnowski Damian, Bardan Magdalena

Przegląd Budowlany

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2023

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R. 94, nr 7-8

65--69

PL

Celem eksperymentu była ocena wpływu temperatury utwardzania na wybrane właściwości użytkowe wyrobów do łączeń konstrukcyjnych. Do badań wytypowano trzy kleje epoksydowe przeznaczone - w ramach naprawy konstrukcji betonowych - do przyklejania materiałów, takich jak np. maty z włókien węglowych, szklanych i aramidowych. Substraty, z których składają się poszczególne kleje, jak również przygotowane obiekty badawcze, kondycjonowano w warunkach laboratoryjnych oraz ekstremalnych temperaturach utwardzania, wytypowanych do projektu w oparciu o informacje znajdujących się w kartach technicznych wyrobów. Jako temperatury ekstremalne przyjęto maksymalną 35˚C i minimalną 10˚C wartość deklarowaną wspólną dla wytypowanych klejów. Przeprowadzono badania, których wyniki stanowią podstawowe kryterium oceny jakości połączeń klejowych, takie jak: wytrzymałość na ścinanie (przy różnych wartościach kąta nachylenia złącza), wytrzymałość na ściskanie i zginanie. Dodatkowo wykonano badanie przyczepności betonu starego do betonu starego, które pozwoliło określić, jaki wpływ ma temperatura utwardzania na połączenie kleju i betonu. Analiza uzyskanych wyników wykazała wpływ temperatury utwardzania wyrobów do łączeń konstrukcyjnych na ich wybrane właściwości użytkowe. Większy wpływ na obniżenie poziomu uzyskanych parametrów ma spadek temperatury utwardzania klejów do łączenia konstrukcyjnego do 10°C.

EN

The aim of the experiment was to evaluate the influence of the hardening temperature on selected performance properties of products for construction joints. Three epoxy adhesives were selected for the tests, intended - as part of the repair of concrete structures - for gluing materials such as carbon, glass and aramid fiber mats. The substrates, which make up the individual adhesives, as well as the prepared research objects, were conditioned in laboratory conditions and extreme hardening temperatures, selected for the project based on the information contained in the technical data sheets of the products. The maximum 35˚C and minimum 10˚C declared values shared by the selected adhesives were adopted as extreme temperatures. Tests were carried out, the results of which constitute the basic criterion for assessing the quality of adhesive joints, such as: shear strength (at different values of the angle of inclination of the joint), compressive and bending strength. In addition, the adhesion test of the old concrete to the old concrete was performed, which allowed to determine the influence of the hardening temperature on the bonding of the adhesive and concrete. The analysis of the obtained results showed the influence of the hardening temperature of products for construction joints on their selected performance properties. The decrease in the curing temperature of structural adhesives to 10°C has a greater impact on the reduction of the obtained parameters.

6

Physicochemical and Mechanical Characterization of Ceramic Materials from Meknes Region (Morocco)

Mesrar Hamza, Mesrar Laila, Jabrane Raouf

Journal of Ecological Engineering

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2023

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Vol. 24, nr 8

183--197

EN

This scientific paper presents a comprehensive study of the physical and chemical properties of a clay sample collected from Meknes region of Morocco. X-ray diffraction analysis revealed the presence of kaolinite, muscovite, and quartz minerals in the clay sample. X-ray fluorescence analysis showed that the sample contained a significant amount of aluminum and silica. The Atterberg limit test indicated that the clay has a high plasticity index and is classified as a clay of low to medium plasticity. The ATG_DSC analysis revealed that the sample underwent multiple endothermic reactions, including dehydration, dehydroxylation, and decarbonation, at different temperature ranges. Shrinkage and weight loss experiments showed that the clay exhibited high shrinkage and weight loss upon drying. SEM-EDX analysis provided information on the microstructure and elemental composition of the clay sample. The water absorption test revealed that the clay has a low water absorption capacity. The three-point flexural test showed that the clay bricks had high flexural strength, which makes it suitable for use in high-stress applications. Overall, the results suggest that the clay sample can be used in a variety of applications, including building materials, ceramics, and other industrial uses.

7

Mechanical Properties of Polypropylene Composites with Different Reinforced Natural Fibers – A Comparative Study

Simamora Pintor, Simanjuntak Josua, Sinulingga Karya, Laksono Andromeda Dwi

Journal of Ecological Engineering

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2023

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Vol. 24, nr 7

311--317

EN

Developing environmentally friendly and recyclable natural fiber-reinforced polymer composites has recently attracted researchers’ attention and interest. Herein, a comparative study was conducted to compare the mechanical properties of polypropylene (PP) composites with different natural fiber reinforcement, including palm fiber (Arenga pinnata), rice straw (Oryza sativa), coconut husk (Cocos mucifera), old world forked fern leaves (dicranopteris linearis), and snake plant (Sansevieria trifasciata). This study aimed to compare the influence of the five natural fiber materials on the tensile strength and flexural strength of PP composites. The natural fibers were chemically treated with a 5% NaOH solution for 2.5 hours. In the preparation of composites, polypropylene as the matrix is heated to 300 °C and mixed randomly with natural fibers. The test results indicate that the composite with the highest tensile strength (38% higher than the lowest) and flexural strength (102% higher than the lowest) is obtained using the PP composite with reinforced rice straw fiber. In contrast, the PP composites with palm fiber have the lowest tensile strength (72% from the highest tensile strength) and the lowest flexural strength (UFSmin) (62% from the highest flexural strength) corresponds to the PP composites with coconut fiber. This study revealed that the flexural strength of all composite samples was greater than that of pure PP.

8

Effect of Potable, Acidic and Alkaline Water Curing on Flexure Strength of Strengthened and Unstrengthen Reinforced Concrete Beams

Barkale Akshay D., Thakare Sunil B.

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 2

153--161

EN

The rapid growing population has resulted into the need of additional capacities of existing infrastructure facilities, commercial buildings etc. Also, the revisions of codal provisions has made many existing structures fall out of the safety criteria mandated by these provisions. In such scenario, from environmental point of view it is always better to strengthen the existing structure than demolish it and cause pollution. Such structures are made to withstand greater load than their capacity by means of supplementary systems also known as strengthening schemes. Recently, Fiber Reinforced Polymer (FRP) is in wide use in strengthening aspect due to its various advantages. Also, Potable Water is a scarcest commodity these days. Its significance in construction industry have been vital. Concrete and water being the most utilized construction materials, this paper examines the effect of different pH water levels on flexure capacity of concrete beams with and without the strengthening system. Eighteen numbers of concrete beams with conventional reinforcement are casted with size of 500x100x100 mm3. These beams are divided into six categories so that each category has three number of beams. The beams are categorized based on the FRP application and pH value of curing solution. Three types of water is used with pH in the range of 4 to 5, pH of 7.5 and pH in the range 9 to 10. Single layer of Glass Fiber Reinforced Polymer (GFRP) fabric sheet is used for flexure strength enhancement. All beams are tested using flexural test till failure. Salient points viz. load and deflection at which first crack, service and failure. These points are noted for each beam and average of three beams of a group is presented as final reading. Suitable conclusions are drawn from these test results.

9

Effect of fiber content on tensile and flexural strength of water lily fiber reinforced polyester resin composite

Mesfin Solomon, Rengiah Robinson Gnanadurai, Shiferaw Melese, Guadie Tesfa

Composites Theory and Practice

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2023

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R. 23, nr 3

113--117

EN

Ethiopia has abundant invasive aquatic plants like water hyacinth and water lily. Large masses of these invasive plants have a negative impact on the country’s water bodies, specifically at Lake Tana in Ethiopia, by infesting and deteriorating water quality and reducing the quantity of water. In this research work, an attempt was made to fabricate a natural fiber reinforced composite in which water lily fiber was used as the reinforcing material in a polyester resin matrix. Chopped water lily fiber reinforced polyester resin composites were prepared by varying the fiber content - 20, 40 and 60 wt.%. Mechanical properties such as tensile strength and flexural strength were tested as per ASTM standards to evaluate the influence of the fiber contents. The experimental results show that an increase in the fiber content enhanced the mechanical properties of the water lily fiber reinforced polyester composite. It was found that the composite with 40 wt.% fiber exhibited superior strength which could be suitably used for different applications.

10

Badanie wpływu uszkodzeń powstałych w badaniu wytrzymałości na zginanie na wytrzymałość na ściskanie materiałów budowlanych

Hafçı Alkan

Cement Wapno Beton

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2023

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R. 28, nr 4

268--282

PL

Beton, czyli główny materiał sektora budowlanego, był przedmiotem wielu badań naukowych przez dziesięciolecia. W wyniku tych badań uzyskano nowe informacje naukowe na temat słabych punktów materiałów cementowych, szczególnie betonu, ich zachowania pod obciążeniem itp. W świetle tych informacji zaleca się, aby niektóre metody badawcze określone w normach międzynarodowych zostały zrewidowane. W niniejszym badaniu zbadano wpływ uszkodzeń spowodowanych przez badanie wytrzymałości na zginanie przeprowadzane na próbkach przygotowanych z beleczek z zaprawy o wymiarach 160 mm x 40 mm x 40 mm w ramach norm EN 13813, EN 13888, EN 13279-1, EN 197-1, TS 13566 i TS 13687, na wyniki badania wytrzymałości na ściskanie przeprowadzonego na złamanych próbkach. W końcowej analizie zaproponowano pewne sugestie dotyczące ulepszenia metody badawczej.

EN

Concrete, the principal material of the construction sector, has been the subject of many scientific researches for decades. As a result of these investigations, new scientific information has been obtained on the weak points of cement-based products, especially concrete, their behaviour under load, etc. In light of this information, it is recommended that some test methods specified in international standards be revised. In this study, the effect of damage caused by flexural strength test performed on samples prepared with mortar prisms, of dimensions 160 mm x 40 mm x 40 mm within the scope of EN 13813, EN 13888, EN 13279-1, EN 197-1, TS 13566 and TS 13687 standards, on the results of compressive strength test performed on the broken samples was investigated. In the final analysis, some improvement suggestions have been made in the test methods in question.

11

Engineering properties of self-compacting concrete incorporating PET fibres and recycled fine concrete aggregates

Bayah Meriem, Debieb Farid, Kadri El-Hadj, Bentchikou Mohamed

Budownictwo i Architektura

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2023

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Vol. 22, no 4

71--95

EN

Concrete is currently the most frequently used material in the building sector due to its favourable properties. However, the proliferation of waste poses a significant environmental problem. Over the past three decades, researchers have explored the use of construction and demolition waste (CDW) as well as plastic waste as aggregates, binders, and fibres in construction materials. This approach has emerged as a notable solution to address environmental and economic challenges. The objective of this research is to assess the impact of polyethylene terephthalate fibres (PETF) on the behaviour of self-compacting concrete (SCC) with recycled fine concrete aggregates (RFCA). Natural fine aggregates (NFA) were used as a substitute for RFCA at different mass fractions (0–100%). Additionally, four volumetric fractions (Vf) of PETF (ranging from 0.3% to 1.2%) were added, and the findings revealed an improvement in the flexural strength and modulus of elasticity of the composite material obtained. However, as the Vf content of PET fibres and RFCA increased, the compressive strength decreased, negatively affecting water absorption by immersion and capillary water absorption. Using 100% RFCA and 1.2% PETF enhanced the modulus of elasticity and flexural strength of recycled self-compacting concrete (RSCC) by up to 25% and 9%, respectively.

12

Laboratory tests of solid and hollow concrete beams made with glass waste

Alharishawi Salam Salman Chiad, Rajaa Nagham, Jabur Aqeel Raheem

Archives of Civil Engineering

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2023

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Vol. 69, nr 4

5--20

EN

The application of used glazed waste in concrete production can improve the performance of the structure of the building. Flexural and shear behavior and action of reinforced Hollow Glass Concrete Beams (HGCB) and Solid Glass Concrete Beams (SGCB) made with glass waste under a two-point load are studied in this paper. In this work, 6 reinforced concrete solid and hollow beams were tested under a four-point bending test to evaluate and calculate the flexural behavior of SGCB and HGCB. For that purpose, Beams were prepared with 1000 mm length, 230 mm height, and 120 mm. All beams were divided into groups and named according to the space stirrups steel bar. The experimental work investigates five main variables which are: first: the comparison between SGCB and HGCB with the concrete beams made with glass waste (Glass Concrete Beam GCB), second: comparison between Solid Concrete Beams for Normal Concrete Beams (NCB), and GCB, three: comparison between Hollow Concrete Beams for NCB and GCB, four: the comparison between HGCB and HCB, last: the comparison between SGCB and SCB. The test results indicated that GCB was offered higher strength than NCB, but the load-slip behavior of all specimens is similar for both types of concretes, and the bond strength is not influenced by steel specimens. Furthermore, the results of this study indicated that the contribution of GCB to the load is indicated to be considerable. The results indicate that the hollow opening affected the ultimate load capacity and deflection of HGCB.

13

Enhancing the flexural load capacity of the reinforced concrete simply supported slabs using damaged tires strips (DTS)

Ali Saba, Alalikhan Ahmed

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2022

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Vol. 31, No. 2

101--112

EN

Damaged tires or ended-life tires represent a difficult problem due to their ability to sustain for a long time which are not able to be dissolved easily. Present study focuses on the ability of using the damaged tires strips (DTS) in the field of structural engineering as an innovative reinforcing material used additionally with the main reinforcement. The adopted technique in the present work represents a clean solution to reuse and recycle DTS to increase the ultimate flexural capacity of the reinforced concrete one-way and two-way slabs used in structural systems satisfying clean environment and economic considerations. The tests were conducted upon eight specimens of reinforced concrete one-way slabs (RCOWS) and two specimens of reinforced concrete two-way slabs (RCTWS) reinforced by the DTS as an additional reinforcement. Experimentally obtained results exhibited enhancement for the ultimate flexural load capacity of the RCOWS and RCTWS models reinforced by the DTS in the range of 16–80 and 14.28% respectively, compared to the original reference specimens.

14

Durability of hybrid fiber reinforced concrete at various environmental media

Elhawary Eslam Ibrahim Nasr, Elsafoury Ashraf Hassan, Ahmad Seleem Saleh Elsayed

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2022

|

Vol. 31, No. 2

88--100

EN

Fiber’s addition to concrete mixture attracts researchers to determine the effect of fiber type on durability properties of hybrid performance concrete. In the present work, steel and polypropylene fibers are used in hybrid form in the experimental program. The objective of this paper is to investigate the mechanical properties of hybrid fiber reinforced concrete subjected to four various media: air, water, sodium chloride, and magnesium sulphate with a 7% concentration. The results showed that using hybrid fibers which consist of 1% steel fiber and 0.3% polypropylene fiber improved the compressive strength, splitting tensile strength, and flexural strength for different media for up to 360 days.

15

Badania nad zastosowaniem włókien odpadowych i z recyklingu w płytach cementowych i gipsowych

Brachaczek Wacław, Chleboś Adam

Materiały Budowlane

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2022

|

nr 3

40--43

PL

W artykule przedstawiono wyniki badań wpływu włókien odpadowych z branży garbarskiej i tekstylnej na wytrzymałość na zginanie zapraw cementowych i gipsowych w aspekcie wykorzystania ich do produkcji płyt okładzinowych. Badania przeprowadzono na próbkach zapraw zawierających spoiwo cementowe i gipsowe o wymiarach 12 x 75 x 150 mm. Większy wpływ na poprawę właściwości wytrzymałościowych miały włókna odpadowe w kompozytach zawierających cement. Stwierdzono, że pomimo znacznego zróżnicowania włókien ich dodatek poprawił wytrzymałość na zginanie, co uzasadnia ich zastosowanie w produkcji materiałów stosowanych w budownictwie.

EN

The article presents the results of research on the influence of waste fibers from the tanning and textile industries on the flexural strength of cement and gypsum mortars in terms of their use for the production of facade boards. The tests were carried out on samples of mortars containing cement and gypsum with dimensions of 12 x 75 x 150 mm. Waste fibers in cement-containing composites had a greater impact on the improvement of strength properties. It was found that despite the significant diversification of fibers, their addition improved the flexural strength, which justifies their use in the production of building materials.

16

Three-phases bubble column to polyethylene terephthalate depolymerization for cement mortar composites improvement

Hameed A. M., Alzuhairi M., Ibrahim S. I.

Journal of Achievements in Materials and Manufacturing Engineering

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2022

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Vol. 112, nr 1

5--12

EN

Purpose: This paper aims to prepare depolymerized polyethylene terephthalate (DPET) powder from recycled plastic water bottles. Adding this DPET powder to the cement mortar was also studied. Design/methodology/approach: The adopted PET depolymerization process includes the usage of both ethylene glycol (EG) as solvent and nano-MgO as a catalyst. A bubble column reactor was designed for this process. Five different mortar groups were made; each has different DPET content of 0%, 1%, 3%, 6% and 9% as a sand replacement. The flexural strength testand the water absorption measurement are done after two curing periods: 7 and 28 days. Findings: The research finding demonstrated that the flexural strength of mortar was reduced by increasing the DPET powder percentage and the maximum dropping was 15% when 9% of DPET was added. The ability of the mortar to absorb the water was reduced by 14.5% when DPET powder was 9%. The mortar microstructure is featured with fewer cavities and porosity. Research limitations/implications: This work’s employed bubble column technique is limited only to the laboratory environment and needs to be scaled up within industrial mass production. For future research, it is suggested to decrease depolymerization time by using smaller pieces of plastic water bottle waste and trying other types of nanocatalyst. Practical implications: The modified mortar can be utilized in areas where moisture, rainfalls, and sanitation systems exist. Originality/value: The article claims that depolymerized waste PET improves chemical process efficiency by lowering reaction time and improving mass and heat transfer rates. Besides, this approach saves money. It is found out that the depolymerized plastic waste is much more functional due to its high cohesion capability than being used as small PET pieces.

17

Przegląd metod wzmacniania konstrukcji żelbetowych przy użyciu materiałów kompozytowych

Kotynia Renata

Inżynieria i Budownictwo

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2022

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R. 78, nr 11-12

503--515

PL

W pracy przedstawiono sposoby wzmacniania elementów żelbetowych przy użyciu biernych i czynnych systemów wzmacniania materiałami z włóknami węglowymi CFRP przyklejanymi na powierzchni betonu lub wklejanymi w betonowe bruzdy. Omówiono zagadnienia wzmocnień dotyczące zginania i ścinania sposobem biernym oraz czynne systemy wzmocnień. Zaprezentowano wyniki badań własnych prowadzonych w Katedrze Budownictwa Betonowego PŁ w zakresie wzmocnień na zginanie metodami EBR oraz NSMR przy użyciu biernych i czynnych technik. Dodatkowo przedstawiono wyniki badań własnych wzmocnień na ścinanie przy użyciu taśm i mat przyklejanych na zewnętrznej powierzchni oraz taśm wklejanych metodą NSMR.

EN

The paper presents strengthening methods of reinforced concrete elements using passive and active strengthening systems with CFRP carbon fibre materials bonded on the concrete surface or embedded in concrete grooves. The issues of passive and active flexural and shear strengthening have been discussed. The results of own research, carried out at the Department of Concrete Structures, have been presented in the field of flexural strengthening by EBR and NSMR methods, using both passive and active techniques. Additionally, the results of the own research on shear strengthening using strips bonded on the surface using the NSMR method have been presented.

18

The Influence of Material Configuration of Fibre-Metal Laminates with Alumina Core on Flexural Strength

Frankiewicz Mariusz, Karoluk Michał, Dziedzic Robert, Timmel Tristan, Scholz Peter

Fatigue of Aircraft Structures

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2022

|

Iss. 14

18--28

EN

Fibre metal laminates (FMLs) consisting of layers made of PA6 polyamide prepregs reinforced with glass and carbon fibres and an aluminium alloy core are the new variant of the other types used by aerospace FML materials such as GLARE or CARALL. By using a thermoplastic matrix, they can be shaped by stamping processes, which allows for a more efficient production process than classical laminating methods such as vacuum bagging. In addition to the improved impact energy absorption efficiency, the metallic core can be utilised to effectively bond the composite part to adjacent metallic structures. This article presents the influence of the material configuration of fibre-metal laminates consisting of continuous fibre-reinforced thermoplastic outer layers integrated with a layer of metallic aluminium alloy inserts - a number of layers, type and direction of reinforcing fibres - on the static and fatigue flexural properties. In this study, eight laminate configurations were prepared using a one-step variothermal consolidation process. The results showed that in the three-point flexural fatigue test, the samples exceeded 106 cycles at stresses <30% of the static bending strength. Laminates with predominantly longitudinally reinforced layers showed the highest fatigue strength among the FML samples analysed. The type of reinforcing fibres and the number of layers were less affected on the analysed mechanical properties.

19

Properties and characteristics of alkali treated Calotropis gigantea fiber-reinforced particle-filled epoxy composites

Jeyapragash R., Sathiyamurthy S., Srinivasan V., Prithivirajan R., Swaminathan G.

Composites Theory and Practice

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2022

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R. 22, nr 2

99--105

EN

The presence of particles and fibers as reinforcement in a polymer matrix greatly enhances the mechanical properties. Agricultural residues and natural fibers are commonly used nowadays due to the fact that they easily decompose even after a longer period and they are eco-friendly in nature. f Fiber that was extracted from stem of Calotropis gigantea was selected as reinforcement in the present investigation. Initially the fiber was treated with a sodium hydroxide solution and CG fiber-epoxy composites were prepared. The properties of alkaline treated CG fiber-reinforced epoxy composites were further improved by the addition of particles such as chitosan, red mud and rice husk. Properties such as the tensile strength, flexural strength, impact toughness, hardness, water absorption, thickness swelling behaviour, specific wear rate and coefficient of friction were evaluated and compared. The XRD pattern of the chemically treated CG fiber-reinforced parrticle-filled epoxy composites was presented in the present study.

20

Flexural Properties of Thin Fly Ash Geopolymers at Elevated Temperature

Ng Yong-Sing, Liew Yun Ming, Heah Cheng Yong, Al Bakri Abdullah Mohd Mustafa, Ng Hui-Teng, Chan Lynette Wei Ling

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 3

1145--1150

EN

This paper reports on the flexural properties of thin fly ash geopolymers exposed to elevated temperature. The thin fly ash geopolymers (dimension = 160 mm × 40 mm × 10 mm) were synthesised using 12M NaOH solution mixed with designed solids-to-liquids ratio of 1:2.5 and Na2SiO3/NaOH ratio of 1:4 and underwent heat treatment at different elevated temperature (300°C, 600°C, 900°C and 1150°C) after 28 days of curing. Flexural strength test was accessed to compare the flexural properties while X-Ray Diffraction (XRD) analysis was performed to determine the phase transformation of thin geopolymers at elevated temperature. Results showed that application of heat treatment boosted the flexural properties of thin fly ash geopolymers as the flexural strength increased from 6.5 MPa (room temperature) to 16.2 MPa (1150°C). XRD results showed that the presence of crystalline phases of albite and nepheline contributed to the increment in flexural strength.