Wyniki wyszukiwania - BazTech

1

Effect of hybrid steel-polypropylene fiber on punching shear behavior of flat slab with an opening

Zaezue Shahzinan J., Hadi Waleed K.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2023

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Vol. 32, No. 1

3--17

EN

This research aimed to gain a better understanding of how the addition of fiber influences the punching shear capacity of two-way slabs by conducting an experiment into the structural behavior of flat slabs with and without a square opening using different volume fractions of hybrid steel-polypropylene fiber (0%, 0.9%, 1.05% and 1.8%). Ten 700 × 700 × 70 mm slabs were divided into five pairs, with two samples used as control samples (with and without openings), and eight other samples with different volume fraction of fibers. Results showed that an increase in fiber content enhanced the shear strength of the slabs. For example, as the volume fraction of hybrid fiber increased from 0.0 to 1.8%, the ultimate load increased by 52% for slabs without an opening and up to 42% for slabs with an opening.

2

Wykorzystanie zdolności pochłaniania energii do wyznaczania wytrzymałości resztkowych fibrokompozytów

Głodkowska Wiesława, Laskowska-Bury Joanna, Lehmann Marek

Materiały Budowlane

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2023

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nr 3

1--4

PL

W artykule omówiono sposób wyznaczania wytrzymałości resztkowych z wykorzystaniem zdolności pochłaniania energii przez fibrokompozyt. Badania przeprowadzono przez zginanie płyt o przekroju kwadratowym podpartych przegubowo na obwodzie. Określone w ten sposób wytrzymałości resztkowe cechują się znacznie mniejszym współczynnikiem zmienności niż wyznaczone wg PN-EN 14651:2007. Opisane badanie jest alternatywą dla 3-punktowego zginania belek i pozwala na wyznaczenie tej cechy z większą wiarygodnością.

EN

The article discusses the method of determining residual strength using the energy absorption capacity of fibrecomposite. The research was carried out by bending square cross-section plates simply supported at the perimeter. The residual strengths determined in this way are characterized by a much lower coefficient of variation than those determined using the normative method according to PN-EN 14651:2007. The described test is an alternative to 3-point bending of beams and allows to determine this feature with greater reliability.

3

Flexural performance of hybrid fiber reinforced cement-based materials incorporating ceramic wastes

Wu Lipeng, Li Xuanhao, Deng Hai

Archives of Civil Engineering

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2023

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Vol. 69, nr 3

491--506

EN

Ceramic waste generated by demolition and manufacturing processes is a kind of widely discharged solid waste; its sustainable use can reduce resource extraction, energy consumption, and carbon emissions, thereby reducing the environmental impact. In this study, ceramic powder and ceramic sand were prepared using waste ceramic wall tiles. By using three water-to-binder ratios of 0.30, 0.32, and 0.34, five ceramic powder replacement rates of 10% to 50%, and completely using ceramic sand as the fine aggregate, specimens with large differences in mechanical properties were prepared. Firstly, the compressive strength was investigated. On this basis, hybrid fibers were employed to strengthen the new matrix material, and its bending resistance was experimentally studied. It was found that the incorporation of ceramic powder reduced the compressive strength of the matrix. The water-binder ratio significantly affects compressive strength at an early age. The effect of PVA fiber on improving the ductility of the new composite is distinct. Increasing the amount of steel fiber can effectively enhance the bending bearing capacity.With a ceramic powder dosage of 50%, the new composite has shown ductile failure characteristics, even with low total fiber content. The bending properties of this new composite material, which makes extensive use of ceramic waste, are well adjustable. The bearing capacity and ductility balance can be achieved with the steel fiber content of 1% and the PVA fiber content of 1.2% to 1.50%.

4

Behavior of prestressed fiber-reinforced steel-lined concrete slabs under projectile impact

Almusallam Tarek, Abbas Husain, Hodali Omar, Siddiqui Nadeem, Al-Salloum Yousef

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 1

art. no. e64, 2023

EN

Recently, investigators have found that the application of prestressing, addition of fibers, and steel lining can improve concrete's overall performance, including its impact resistance. There is, however, no study in the available literature on the impact response of steel-lined post-tensioned fiber-reinforced concrete (PFRC). This study examines how steel-lined PFRC responds to projectile impact. The PFRC slabs with/without a steel lining on the rear face were tested against the impact of hemispherical-nosed projectiles at varied velocities using a gas-gun facility. The test results revealed that steel fiber volume increased the ballistic limit, reduced penetration and scabbing depths, and reduced ejected mass substantially from the back face. The use of steel lining on the back face caused a substantial increase in the ballistic limit and caused a significant reduction in the ejected mass. NDRC equations are modified to incorporate the effects of prestressing, steel fibers, and steel lining to predict penetration depth. Another empirical model is developed for ballistic limit prediction of the prestressed steel-lined fiber-reinforced concrete slab by incorporating the prestressing, steel fibers, and steel lining in the UKAEA formula. The models agreed well with the experimental results.

5

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

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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.

6

Wpływ włókien stalowych z recyklingu opon na cechy wytrzymałościowe betonu

Michalik Agnieszka, Chyliński Filip, Kupisz Piotr, Zacharski Łukasz, Pichór Waldemar

Inżynieria i Budownictwo

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2022

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R. 78, nr 9-10

397--400

PL

W artykule przedstawiono wyniki badań wytrzymałościowych betonów z dodatkiem oczyszczonych włókien stalowych z recyklingu opon (RTSF) w porównaniu z taką samą ilością włókien stalowych produkowanych przemysłowo (MSF). Wykonano badania wytrzymałości na zginanie, ściskanie, rozłupywanie i wytrzymałości resztkowe na rozciąganie przy zginaniu.

EN

The article presents the results of strength tests of concretes with the addition of purified recycled tyre steel fibers (RTSF) in comparison with the same amount of manufactured steel fibers (MSF). Flexural strength, compressive strength, tensile splitting strength and residual flexural tensile strengths were performed. The test results show that concretes with the addition of RTSF have higher strength properties than the reference concretes with the same amount of MSF fibers, which is a potential for their application.

7

Pro-Ecological Utilization of Crushed Concrete as an Aggregate to Improve the Compressive Strength with Steel Fibers and Styrene-Butadiene Rubber Latex

Awchat Ganesh D., Monde Amruta S., Sirsikar Rajat A., Dhanjode Gopal C., Tayade Suhas E., Rathore Shailendra S.

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 3

95--105

EN

Demolition of old structures and pro-ecological utilisation of such demolished concrete waste materials must be considered an important ecological issue that helps conserve non-renewable natural resources. Crushed concrete in the form of recycled coarse aggregate (RCA), steel fibres (SF) of 30–50 kg/m3 and styrene-butadiene rubber (SBR) latex of 5%, 10%, and 15% by cement weight attempted to strengthen the strength in compression of polymer modified steel fiber reinforced crushed concrete (PMSFRCC). Ninety-nine cubes each of M20, M25, M30, and M40 grade were cast separately to assess the strength in compression of natural aggregate concrete (NAC), crushed concrete (CC), and PMSFRCC. According to the experimental results, PMSFRCC with SF 30 kg/m3 and SBR Latex 5% by weight of cement improves compressive strength by 8.92% & 6.22% in mix-1, 7.63% & 5.45% in mix-2, 4.27% & 7.87% in mix-3, and 9.87% & 7.46% in mix-4 when compared to NAC at 28 and 90 days.It reflects significant improvement and validation of utilisation of CC as a potential source of an aggregate to improve compressive strength for the desired purpose.

8

Badania doświadczalne wpływu włókien hybrydowych na zachowanie się belek żelbetowych przy zginaniu

Shanthi Vengadeshwari R., Jagannatha Reddy H.N., Prabhakara R.

Cement Wapno Beton

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2022

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R. 27, nr 1

59--70

PL

Dodatek włókien jest obiecującym rozwiązaniem, poprawiającym zachowanie belek żelbetowych przy zginaniu. Wpływa na poprawę właściwości tych belek w zakresie obciążenia szczytowego, plastyczności i absorpcji energii. Nieefektywne włókna mono w betonie działają bardzo efektywnie, gdy są połączone poprzez hybrydyzację i przyczyniają się do zwiększenia wytrzymałości. Hybrydyzacja włókien zapewnia poprawę właściwości mieszanki betonowej i stwardniałego betonu. Dla zapewnienia optymalnych właściwości użytkowych ważniejszy jest synergiczny efekt włókien. Wprowadzenie dwóch rodzajów włókien do matrycy betonowej skutecznie mostkuje rysy. W celu zbadania wpływu hybrydyzacji włókien na zginanie, przygotowano belki żelbetowe, przeprowadzono doświadczenia i porównano wyniki z belkami kontrolnymi. W niniejszej pracy zamierzano ocenić i porównać wpływ włókien stalowych i bazaltowych, w postaci mono i hybrydowej, na przebieg zginania, a mianowicie pierwsze obciążenie przy pęknięciu, zachowanie się pod wpływem obciążenia, plastyczność, szerokość pęknięcia i wytrzymałość na zginanie belek żelbetowych. Do oceny właściwości mechanicznych betonu zbrojonego włóknami klasy M40, wybrano udziały objętościowe włókien wynoszące 0,25%, 0,5% i 0,75%. Połączenie włókien bazaltowych z włóknami stalowymi, w znacznym stopniu poprawia właściwości poprzez synergię działania. Na podstawie ogólnej oceny właściwości mechanicznych ustalono, że połączenie włókien bazaltowych i stalowych w ilości odpowiednio 0,25% i 0,75%, dało najlepsze wyniki. Optymalne udziały objętościowe tych włókien zastosowano do wykonania belek. Tam, gdzie było to możliwe, wyniki prób zginania były weryfikowane z normami indyjskimi.

EN

Addition of fiber is a promising solution, to enhance the flexural behaviour of reinforced cement concrete [RCC] beams. It improves the peak load, ductility and energy absorption characteristics of RCC. Ineffective mono fibers in the concrete perform very effective, when combined through the hybridization and contribute towards the strength. Fiber hybridization offers appreciable improvement in fresh and hardened properties of concrete. To achieve optimum performance, synergetic effect of fibers is more important. Incorporation of two fibers in concrete matrix, bridges the cracks effectively. Hence to investigate the effect fiber hybridization in the flexural performance, RCC beams were cast, experimented and the results were compared with the control beams. In the present study, it is intended to evaluate and compare the impact of steel and basalt fibers in mono form and hybrid form, on the flexural parameters such as first crack load, load response behaviour, ductility, crack width and flexural strength of RCC beams. To evaluate the mechanical properties of M40 grade fiber reinforced concrete, volume fractions chosen were 0.25%, 0.5% and 0.75%.Comparatively addition of basalt fibers with steel fibers, improves synergetic response to a considerable extent. From overall assessment of the mechanical properties, it was established that the combination of basalt and steel fibers at 0.25% and 0.75% respectively, produced optimum results. Optimum volume fraction of fibers identified is used in the casting of RCC beams. Wherever possible, flexural parameters were cross checked, with Indian Standards.

9

Review on Mechanical Properties of Metakaolin Geopolymer Concrete by Inclusion of Steel Fibers

Faris Meor Ahmad, Al Bakri Abdullah Mohd Mustafa, Muniandy Ratnasamy, Ramasamy Shamala, Abu Hashim Mohammad Firdaus, Junaedi Subaer, Sandu Andrei Victor, Tahir Muhammad Faheem Mohd

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

261--267

EN

This study summarised the recent achievement in developing fiber reinforced geopolymer concrete. The factor of replacing Ordinary Portland Cement (OPC) which is due to the emission of carbon dioxide that pollutes the environment globally is well discussed. The introduction towards metakaolin is presented. Besides, the current research trend involved in geopolymer also has been reviewed for the current 20 years to study the interest of researchers over the world by year. Factors that contribute to the frequency of geopolymer research are carried out which are cost, design, and the practicality of the application for geopolymer concrete. Besides, the importance of steel fibers addition to the geopolymer concrete is also well discussed. The fundamental towards metakaolin has been introduced including the source of raw material, which is calcined kaolin, calcined temperature, chemical composition, geopolymerisation process, and other properties. Alkali activators which are mixing solution between sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) have been reviewed. The mechanical properties of fibers reinforced metakaolin-based geopolymer concrete which is compressive and flexural are thoroughly reviewed. The compressive and flexural strength of fiber-reinforced metakaolin geopolymer concrete shows some improvement to the addition of steel fibers. The reviews in this field demonstrate that reinforcement of metakaolin geopolymer concrete by steel fibers shows improvement in mechanical performance.

10

Post-fire impact behavior and durability of steel fiber-reinforced concrete containing blended cement-zeolite and recycled nylon granules as partial aggregate replacement

Nematzadeh Mahdi, Nazari Ali, Tayebi Morteza

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e5, 2022

EN

Recycling polymeric waste in concretes to replace a portion of the stone aggregate volume can improve some of the mechanical features of concrete such as impact resistance, while also helping mitigate the associated environmental problems. Thus, this research was aimed at exploring the combined effect of nylon granules (0, 10, and 20%) as a replacement for fine aggregate, steel fibers (0, 0.75, and 1.25%), and zeolite (0, 10, 15, and 20%) as a replacement for cement on the impact resistance and durability of concrete following several heating levels (20, 300, and 600 °C). For this purpose, 432 concrete samples were manufactured, and the concrete features including compressive strength, tensile strength, impact resistance, loss of weight, water absorption, porosity, density, and failure type of concrete samples after different heating levels were investigated. The results demonstrated that the impact energy at the failure level declined considerably with temperature for all the concrete samples containing nylon granules and steel fibers (by 46–94% for 600 °C). However, increasing nylon granule content to 20% in concrete improved the impact resistance at the first and ultimate crack levels following exposure to 20 and 300 °C, while significantly lowering this parameter (by up to 40%) following exposure to 600 °C. Furthermore, the inclusion of steel fibers in concrete and increasing its content led to increased impact energy of the heated and non-heated concretes.

11

Fire performance of ultra‑high performance concrete: effect of fine aggregate size and fibers

Zhang Dong, Tan Kang Hai

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 3

art. no. e116

EN

This study conducted a thorough investigation on the combined effects of fine aggregate (FA) size, steel fiber, and polypropylene (PP) fiber on the spalling behavior and mechanical properties of ultra-high-performance concrete (UHPC) at high temperature. FAs with 0.6, 2.36, and 4.75 mm were incorporated with steel fibers or PP fibers in UHPC. Test results showed that the synergistic enhancement in spalling prevention of UHPC at high temperature was only found in the combination of PP fiber and large-sized FA. Large-sized FA not only increased the fraction of microcracks but also enhanced their connectivity in UHPC with PP fibers, thus increasing the permeability and improving the spalling resistance at high temperature. This reduced the required PP fiber content for spalling prevention. Besides, steel fibers and large-sized FAs had a combined negative effect on mechanical properties above 600 °C, resulting in even lower mechanical properties at 900 °C compared to UHPC without any fiber and UHPC with PP fibers. Microstructural observation also found that the degradation of steel fibers and microcracks generated by expansion of aggregate both severely damaged the microstructures of UHPC at 900 °C. By contrast, adding PP fibers reduced compressive strength of UHPC below 600 °C due to the voids left by the decomposition of PP fibers, but it did not affect compressive strength at 900 °C, as the cracks in the matrix was enlarged, which reduced the negative effect of PP fibers.

12

Engineering of ultra-high performance self-compacting mortar with recycled steel fibres extracted from waste tires

Abdolpour Hassan, Niewiadomski Paweł, Sadowski Łukasz, Kwiecień Arkadiusz

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e175, 2022

EN

The main novelty of this study is producing Ultra High-Performance Self Compacting Mortar (UHPSCM) incorporated Recycled Steel Fibre (RSF) from waste tires. For this purpose, different mix compositions including 0%, 1%, and 3% RSF content in terms of volume were proposed. Self-compacting ability was assessed using mini-cone tests, while nondestructive testing has been used to evaluate the effect of RSF inclusion on the compaction of UHPSCM constituent materials. Mechanical performances were investigated using compression and unnotched flexural tests. Residual flexural strength in both service limit state (SLS), ultimate limit state (ULS), and two equivalent flexural strengths were evaluated under notched flexural tests and analysed using statistical approaches. Concrete Damage Plasticity (CDP) has been employed for the analysis behaviour of developed mortars under different loadings. Additionally, an element deletion approach was used to evaluate the fracture of UHPSCM under compression and flexural loadings. The experimental results showed that adding 1% and 3% of RSF resulted in decreasing workability by 3% and 22%, respectively. Improving compressive strength by 16% and 22% and flexural by 7% and 8% were noticed in the case of samples with 1% and 3% fiber, respectively, in 28 days. In spite of the significant improvement of post-cracking behaviour of samples with 3% of RSF, this behaviour was insignificant for the samples with 1% of RSF. However, with less amount of fibre inclusion, brittle failure can be altered to ductile failure. Moreover, the behaviour of the tested specimens under different loadings was successfully predicted using Finite Element (FE) simulations.

13

Shear performance of reinforced self-compacting concrete beams incorporating steel and polypropylene fibers

Alkhattat Saja S., Al-Ramahee Munaf A.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2021

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Vol. 30, No. 4

537--551

EN

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.

14

The effect of varied types of steel fibers on the performance of self-compacting concrete modified with volcanic pumice powder

Magbool Hassan M., Zeyad Abdullah M.

Materials Science Poland

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2021

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Vol. 39, No. 2

172--187

EN

The aim of this work involves studying the impact of varied types of steel fibers (SF) on the performance of self-compacting concrete (SCC), containing volcanic pumice powder (VPP). In this study, five types of steel fiber, which had a hooked end with two lengths of (SF1) and (SF3), flat end of length (SF2), in addition to the pointed end of (SF4) and (SF5) by 1% of volume fraction, were used. In addition, hybrid steel fiber (a mixture of all the steel fiber types) by 0.2% of volume fraction of concrete volume was used. Moreover, VPP was utilized by 30% cement mass as a substitute material for producing SCC. The impact of steel fiber properties in the shape of SF on the fresh concrete properties as slump flow and segregation were investigated. In addition to their influence on the compressive strength, split tensile strength, flexural strength, toughness, porosity, water absorption, and bulk density were examined. The results showed that SF led to decreasing the SCC fresh properties. Utilizing SF, on the other hand, improved the SCC hardened properties, as well as the toughness indices.

15

Wpływ włókien polimerowych na wytrzymałość na ściskanie i rozciąganie betonu w świetle norm PN-EN 206 i PN-EN 14651

Blazy Julia, Drobiec Łukasz

Inżynieria i Budownictwo

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2021

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R. 77, nr 8

391--396

PL

Przedstawiono możliwość zastosowania normy PN-EN 14651, przeznaczonej do badania betonów z fibrą stalową, do określenia wytrzymałości na rozciąganie przy zginaniu betonów z dodatkiem 2,0 i 3,0 kg/m3 włókien polimerowych o różnej geometrii i formie. Pozostały skład mieszanki betonowej był niezmienny w przypadku każdej serii. Opisano również użyte materiały, metodykę badań oraz wyniki badań konsystencji i wytrzymałości na ściskanie betonów z fibrą i bez fibry. Przeprowadzono analizę uzyskanych wyników i podsumowano wpływ włókien niemetalicznych na właściwości betonu.

EN

In the article, the possibility of use the PN-EN 14651 standard, intended for testing concretes with steel fibers, to determine the flexural strength of concrete with the addition of 2.0 and 3.0 kg/m3 of polypropylene fibers of different geometry and form was presented The remaining composition of the concrete mix was the same for each series. Additionally, the used materials, the methodology of tests, results of consistency tests and the evaluation of the compressive strength of concrete with and without fibers were discussed. Finally, the obtained results were analyzed and the influence of non - metallic fibers on the properties of concrete was summarized.

16

Badania eksperymentalne na docisk lekkiego betonu kruszywowego wzmocnionego stalowym zbrojeniem rozproszonym

Krawczyk Łukasz, Urban Tadeusz

Inżynieria i Budownictwo

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2021

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R. 77, nr 8

386--390

PL

Zaprezentowano wyniki badań walców o wymiarach 150 × 300 mm. Elementy były wykonane z betonu lekkiego oraz betonu lekkiego z włóknami stalowymi. Zostały obciążane przez walce stalowe o różnej średnicy. Otrzymane wyniki porównano z wartościami obliczonymi zgodnie z normą PN-EN-1992-1-1. Ze względu na rozbieżności zaproponowano autorskie wzory opisujące wyniki otrzymane z badań.

EN

The article presents the results of the tests of cylinders 150 × 300 mm. The elements were made of plain and fiber reinforced lightweight aggregate concrete. They were loaded by steel cylinders of various diameters. The obtained results were compared with the values calculated in accordance with the PN-EN-1992-1-1 code. Due to the discrepancies, own formulas describing the results obtained from the research were proposed.

17

Experimental investigation of chopped steel wool fiber at various ratio reinforced cementitious composite panels

Rmdan Amer Akrm A., Al Bakri Abdullah Mohd Mustafa, Ming Liew Yun, Aziz Ikmal Hakem A., Mohd Tahir Muhammad Faheem, Abd Rahim Shayfull Zamree, Amer Hetham A. R.

Archives of Civil Engineering

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2021

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Vol. 67, nr 3

661--671

EN

The flexural toughness of chopped steel wool fiber reinforced cementitious composite panels was investigated. Reinforced cementitious composite panels were produced by mixing of chopped steel wool fiber with a ratio range between 0.5% to 6.0% and 0.5% as a step increment of the total mixture weight, where the cement to sand ratio was 1:1.5 with water to cement ratio of 0.45. The generated reinforced cementitious panels were tested at 28 days in terms of load-carrying capacity, deflection capacities, post-yielding effects, and flexural toughness. The inclusion of chopped steel wool fiber until 4.5% resulted in gradually increasing load-carrying capacity and deflection capacities while, provides various ductility, which would simultaneously the varying of deflection capability in the post-yielding stage. Meanwhile, additional fiber beyond 4.5% resulted in decreased maximum load-carrying capacity and increase stiffness at the expense of ductility. Lastly, the inclusion of curves gradually.

18

Durability performance of fibrous high-performance cementitious composites under sulfuric acid attack

Mermerdaş Kasım, Ipek Süleyman, Anwer Ahmed Motesem, Ekmen Şevin, Özen Mustafa

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

203--222

EN

The high-strength concrete having a better compressive strength demeanor can be manufactured by the addition of the fibers which eliminates the inherent weakness, the brittle failure due to lack of tensile strength. In this study, an experimental study covering the enhancement of the mechanical characteristics and the investigation of the performance against the aggressive acid attack of high-performance cementitious composites (HPCC). For this, steel and glass types of fiber were employed in the manufacturing of HPCC, as either single or hybrid at various levels. The HPCC mixtures were designed at a constant water-to-cementitious ratio of 0.25. Portland cement and microsilica were employed in the manufacturing as cementitious material whereas the aggregate was the mix of river and quartz sands. 14 HPCC mixtures were designed and the flowability, unit weight, compressive and flexural strengths, sorptivity index, ultrasonic pulse velocity were tested at various ages. Besides, the loss in the strength, mass, and dimension of HPCC mixtures was also measured after exposure of the mixtures 1- and 2-month aggressive sulfuric acid (H2SO4). Additionally, the experimental results were statistically evaluated through general linear model ANOVA. Based on the results, the highest compressive strength values were observed in the HPCC mixture manufactured with steel fiber. The lowest losses in both flexural and compressive strengths were observed in the mixtures produced with microsilica. Steel fiber addition increased the compressive strength not only after applying the normal curing regime but also after exposing the sulfuric acid. Both flexural and compressive strength of HPCC mixtures were influenced by fiber type and volume fraction. The addition of glass fiber decreased compressive strength.

19

Effect of curing regimes on the mechanical and fresh properties of steel fiber-reinforced concrete

Öztürk Oguzhan, Yenidünya Eren, Keskin Ülkü Sultan

Architecture Civil Engineering Environment

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2021

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Vol. 14, no. 1

69--82

EN

Properties of concrete are affected by its fabrication process such as preparation, mixing, placing, finishing and curing. Since curing process is the ultimate stage of the fresh state of concrete before it is put into service, it is of great significance that is needed to be strictly handled. In the present study, steel fiber reinforced concrete was investigated in terms of different curing regimes including precast technology and comparative analysis was performed. To this end, beams and cubes specimens were fabricated and cured under steam process to represent the applications of precast concrete industry. Findings were compared with the other types of curing regimes. Mechanical behaviors of specimens were evaluated along with their strength development and workability in the presence of steel fiber. Results indicated that adequate workability and mechanical properties were obtained for steam-cured specimens compared to other specimens produced with different curing regimes. However, production parameters such as mixture proportion and fiber dosage were more pronounced for low-strength concrete specimens compared to high strength steam cured concrete specimens.

20

Analysis of fees for connecting the infrastructure of generally accessible charging stations to networks with rated voltage not higher than 1 kV

Ślęzak Anna

Architecture Civil Engineering Environment

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2021

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Vol. 14, no. 1

107--114

EN

On 22 February 2018, the Act on electromobility and alternative fuels came into force (Journal of Laws of 2018, item 317). This legal Act sets out the rules for the development and operation of infrastructure for the use of alternative fuels, which is closely related to the development of electromobility. The Act (2011/C81E/17) regulates and defines, among others obligations in the scope of technical requirements for the construction of a charging station and their minimum number in municipalities. This Act was introduced in order to develop electromobility, which in turn is to contribute to the reduction of CO2 emissions [1]. The aim of the paper is to show the relationship between the geographical location of the connection of road charging infrastructure in our country, and the costs of its connection to the low voltage network, understood as the costs of the connection fee, which are paid to the Distribution System Operators. The costs of the connection fee in the case of power supply from low voltage lines cover the actual connection costs of generally available charging stations, i.e. the connection costs, i.e. the network section used to connect the devices or installations or the network of the entity with the connection capacity required by it, with the remaining part of the Distribution System Operators network. The Distribution System Operator also covers the costs of the measurement and settlement system. In addition, the paper indicates the preferential treatment of connecting charging stations, which are defined as reduced costs of connecting them in relation to other objects.