CC BY
40
STEEL AND BASALT FIBER COMPARISON IN THE FLEXURAL STRENGTH OF
CONVENTIONAL CONCRETE
Saad Musaed Musaed Gubran1, Graduate Student Al-msajdi Sami Abdullah Abdullah Saleh , Graduate Student Nankya Hilda1, Graduate Student
Abdulwahed Baleegh Mohammed Hazaa1, Graduate Student 1Peoples Friendship University of Russia (RUDN University) 2Peter the Great St. Petersburg Polytechnic University
1(Russia, Moscow) 2
2(Russia, Saint Petersburg)
DOI:10.24412/2500-1000-2021-2-1-69-73
Abstract. Plain conventional concrete structural elements are known for their brittleness. This brittleness causes the weakness and failure suffered by these elements. The plain concrete normally contains numerous micro cracksand under sustained loading conditions, it fails in tension. To solve these problems, this paper investigated the effect of dispersed chopped steel and basalt fiber in conventional concrete rectangular prisms. The main objective of this research paper was to determine the flexural strength of basalt fiber and steel fiber reinforced concrete specimens for different fiber dosages and compare the flexural strengths of the two types offiber reinforced concrete with those of control (plain) concrete. The fiber dosages chosen for the study were 0%, 0.5%, 1%, 1.5% of total volume of concrete. Four sets of concrete mixtures were used of which each set produced 9 rectangular prisms which were tested for flexure on day 7, day 14 and day 28 per 3 rectangular prisms. The experimental results showed that addition of chopped fiber increased the flexural strength of the concrete prism. 1.5% fiber gave the best flexural strength in both basalt fiber reinforced concrete and steel fiber reinforced concrete. Basalt fiber reinforced concrete showed more plasticity with lesser cracks than steel fiber reinforced concrete.
Keywords: basalt fiber, steel fiber, Flexural strength, FRC-Fiber reinforced concrete.
Concrete has its own characteristics which has made it popular in structural construction for over a century. Excellent compressive strength, durability and easily available subcomponents has made concrete as a highly demanded building material. Plain concrete has a low strain at fracture and a low tensile strength. The plain concrete contains numerous micro cracks under loading conditions and thus it fails in tension. These deficiencies have led to considerable research in this area to develop new ideas to modify the brittle properties of concrete. In this era of modern civil engineering, structures have their own structural and durability requirements, every structure has its own purpose and hence to meet this purpose, modification in traditional cement concrete has become mandatory.
It has been found that some types of fibers added in concrete in certain proportions improve the mechanical properties, durability,
and serviceability of the structure. Thus fiber-reinforced concrete (FRC) is the most widely used solution for improving the strength properties of concrete [1]. Fiber reinforced concrete contains short discrete fibrous material which increase its structural integrity. In concrete, the fibers are usually uniformly distributed and randomly oriented. The main role of FRC is to control the cracking and crack propagation, and to alter the behavior of the material once the matrix has cracked, by bridging across these cracks and so providing some post-cracking ductility.
The fibers are generally distributed throughout the cross-section. These fibers have an elastic structure, are environmentally safe and non-toxic. Basalt fibers (BF) have high thermal stability and insulating characteristics. BF is a high performance non-metallic, non-corrosive fiber with light weight, good fire resistance and strength [2-
- TexHuuecKue HayKU -
4]. Steel fibers are filaments of wire, deformed and cut to lengths, for reinforcement of concrete, mortar, and other composite materials. It is a cold drawn wire fiber with corrugated and flattened shape. Steel fiber (SF) is made using high quality low-carbon steel wire. SF are usually used in concrete to control cracking and crack propagation due to both plastic shrinkage and drying shrinkage. SF has better ability to withstand repeatedly applied, shock or impact loading. SF also reduces the permeability of concrete and thus reduces bleeding of concrete.
Several studies have been performed on different types of fiber reinforced concrete. According to [5], a comparative study of the effect of BF, glass fibre (GF), and SF on compressive and flexural strength of concrete was made. This study explored the workability and strength of SF and BF reinforced self-compacting concrete of grade M25 with ground granulated blast-furnace slag (GGBS) and super plasticizer. The powder content added was 70% of cement and 30% of GGBS. This was kept constant for all the mixes. The SF and BF percentage were varied from 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, and 2.0% by weight of concrete. The important conclusion of this study was that there is not much improvement in compressive strength in comparison with split tensile strength.
The analysis in [6] came to some conclusions on SF reinforced concrete. This study investigated the optimum quantity of SF required to achieve the maximum flexural strength for M25 grade concrete. Hook end SF was used in this study. From the experimental work, it was found that with increase in SF content in concrete there was an increase in 1.1% of its flexural strength. Compressive behavior of SF reinforced concrete is studied in research [7]. It involves an experimental study to investigate the influence of matrix strength, fiber content and diameter on the compressive behavior of SF reinforced
concrete. Concrete compressive strengths of 35 MPa and 60 MPa, 0.38mm and 0.55 mm fiber diameter and 30 mm fiber length, were considered. The volume of fiber in the concrete was varied up to 1.5%. Test results indicated that the addition of fibers to concrete enhances its toughness and strain at peak stress but can slightly reduce the Young's modulus.
An experimental study was conducted by [8] on the effectiveness of dispersed chopped BF on the fresh and hardened properties of high strength concrete. In this study, two series of mixes were used. The addition of chopped basalt fibers did not help to improve the compressive strength of high strength concrete (HSC). However, fibers have improved tensile and flexural tensile strength of HSC, also the area under the stress strain curves increased.
The main objective of this research paper is to determine the flexural strength of BF and SF reinforced concrete specimens for different fiber dosages and compare the flexural strengths of the two types of FRC with those of the control concrete. The fiber dosages chosen for the study were 0%, 0.5%, 1%, 1.5% of total volume of concrete. Materials required for the concrete mix were procured and prepared according to CIS Interstate Standard GOST 10180-2012 [9].
Materials and methods of experiment
This fiber reinforced concrete comprises of the below listed materials its concrete mix.
- Cement as binder 380 kg/m
- Quartz sand as fine aggregate 665 kg/m3
- Granite as coarse aggregate 1350 kg/m
- concrete modifier MB10-30C = 125 kg/m3
- water = 187.5 l/m3
- chopped BF of 20 mm length, diameter 15 micrometer for BF reinforced 24
kg/m3.(figure 1)
- Steel fiber of 50 mm length, 1mm for SF
"3
reinforced 24 kg/m (figure 2).
Figure 1. Chopped basalt fiber A source:
https://technobasalt.com/products/basalt-fiber/
A total of 7 (seven) sets of conventional concrete mixes were prepared for the rectangular prisms. From each of the set, 9 (nine) concrete rectangular prisms were made from each mix.
The flexural strengths were tested on concrete rectangular prisms of dimensions 100 mm x 100 mm x 400 mm. The rectangular prisms were molded in a metallic form. After pouring the concrete mix in the molds, the molds were covered with polyethylene and kept at room temperature (20 ± 5) °C and relative air humidity (95 ± 5) %. On the 48th
Figure 2. Steel fiber
A source:
https://wondery.en.ecplaza.net/products/concrete-steel-material-steel-fibre-for_4237600
hour, the concrete rectangular prisms were removed from the molds and kept in the curing cupboard till the 28th day then the concrete rectangular prisms were tested for flex-ural strength on a Matest Universal Testing Machine.
Experimental results The results of experimental tests conducted on basalt fiber reinforced concrete (BFRC) rectangular prisms and steel fiber reinforced concrete (SFRC) rectangular prisms are illustrated in table 1 and figures 3 and 4.
Table 1. Average flexural test results of FRC
Curing period, Days Average Flexural Strength (Ff) of FRC, MPa
BFRC SFRC
0% 0.5 % 1% 1.5 % 0% 0.5 % 1% 1.5 %
7 3.15 3.89 4.59 5.98 3.15 3.61 4.01 5.31
14 3.35 4.22 5.06 6.15 3.35 3.97 4.62 5.57
28 3.82 4.91 5.34 6.79 3.82 4.25 4.98 6.03
21
0% SF -»-0.5% SF 1% SF —•—1.5% SF Figure 3. Experimental test result of BFRC Ff
BFRC rectangular prisms showed more flexural strength than SFRC. On day 28 of the curing period, BFRC obtained a maximum flexural strength of 6.79 MPa while SFRC 6.03 MPa. There was 177.7% strength increase for BFRC on day 28 from 0% fiber to 1.5% BF. On the other hand, there was only 157.9% strength increase for SFRC on day 28
a 8,00
£ 6,00
сл
J 4,00
from 0% fiber to 1.5% SF. During testing, it was discovered that BFRC took a longer time to reach its maximum flexural strength. Lesser cracks were seen on the rectangular prisms bearing BF than SF. The SFRC contained an
,3
average density of 2800 kg/m while BFRC had an average density of 2550 kg/m3 hereby confirming the lightness property of BF.
eg Ö Й
M 2,00
I
s0,00
........A............ ЩЩ-—□- =8
9= щш—°—
0% SF
14 21
Curing Period, Days
— 0.5% SF Д 1% SF X 1.5% SF
28
Figure 4. Experimental test result of BFRC Ff
fiber in the concrete increased the flexural strength. BF proved more strength that SF in the conventional concrete prisms.
Conclusion. From the experimental test results, a noticeable increase in the flexural strength of the conventional concrete rectangular prisms was observed. Incorporation of
References
1. Chiadighikaobi P.C., Jean Paul V., Sserunjoji N. Performance evaluation of basalt fiber on the deflection strength of expanded clay concrete beam // Экономика строительства. - 2020. -№ 6 (66). - С. 66-79.
2. Okolnikova G.E. Effect of Modifier Mb10-01 on the Parameters of Fracture Mechanics of High-Strength Coarse-Aggregate Concrete // Australian Ranger Bulletin. - 1986. - №4 (1). -Pp. 9-10.
3. Kharun M. Effect of Basalt Fibers on the Physical and Mechanical Properties of MB Modifier based High-Strength Concrete // Journal of Mechanics of Continua and Mathematical Sciences. 2019. Spl. 1 (4). DOI: https://doi.org/10.26782/jmcms.spL4/2019.11.00008
4. Chiadighikaobi P.C. Effects of basalt fiber in lightweight expanded clay concrete on compressive strength and flexural strength of lightweight basalt fiber reinforced concrete // IOP Conf. Series: Materials Science and Engineering. 2019. Vol. 640. Pp. 1-9. DOI: 10.1088/1757-899X/640/1/012055
5. Satheskumar K., Karthik P. Comparative study on self-compacting concrete using steel fibre and basalt fibre // International Journal of Current Innovation Research. 2016. Vol. 2, Issue 05. Pp. 375-379.
6. Amit R. Some Studies on Steel Fiber Reinforced Concrete // International Journal of Emerging Technology and Advanced Engineering. 2013. Vol. 3, Issue 1. Pp. 120-127.
7. Neves R.D., Fernandes de Almeida J.C.O. Compressive behavior of steel fibre reinforced concrete // Structural Concrete. 2005. Vol. 6. Pp. 1-8. DOI: 10.1680/stco.2005.6.1.1
8. Nasir Shafiq, Muhd Fadhil Nuruddin. Effect of Chopped Basalt Fibers on the Mechanical Properties and Microstructure of High Performance FiberReinforced Concrete // Hindawi Publishing Corporation Advances in Materials Science and Engineering. 2014. Tehmina Ayub, Nasir
0
7
Shafiq, M. Fadhil Nuruddin. Effect of Chopped Basalt Fibers on the Mechanical Properties and Microstructure of High Performance Fiber Reinforced Concrete // Advances in Materials Science and Engineering. 2014. Vol. 2014, 14 pp. DOI: https://doi.org/10.1155/2014/587686
9. GOST 10180-2012. CIS Interstate Standard. Concretes: Methods for Strength Determination using Reference Specimens. Standartinform, Moscow, Russia, 2013. URL: http://gostexpert.ru/gost/gost-10180-2012.
СРАВНЕНИЕ СТАЛЬНЫХ И БАЗАЛЬТОВЫХ ВОЛОКОН В ПРОЧНОСТИ НА
ИЗГИБ ОБЫЧНОГО БЕТОНА
Саад Мусаид Мусид Губран1, магистрант
Аль Мсаджди Сами Абдуллах Абдуллах Салех , магистрант
Нанкя Хильда1, магистрант
Абдулвахид Балиг Мухаммед Хазаа1, магистрант Российский университет дружбы народов
Санкт-Петербургский политехнический университет Петра Великого 1(Россия, г. Москва) 2(Россия, г. Санкт-Петербург)
Аннотация. Не армированные обычные бетонные конструкционные элементы известны своей хрупкостью. Эта хрупкость вызывает слабость и разрушение этих элементов. Обычно неармированный бетон содержит многочисленные микротрещины и при длительных нагрузках выходит из строя. Для решения этих проблем в данной работе было исследовано влияние дисперсной рубленой стали и базальтовой фибры на обычные бетонные прямоугольные призмы. Основной целью данной работы было определение прочности при изгибе образцов базальтовой фибры и стальной фибры для различных доз фибры и сравнение прочности при изгибе двух типов фибры с прочностью контрольного бетона. Дозировки фибры, выбранные для исследования, составили 0%, 0,5%, 1%, 1,5% от общего объема бетона. Было использовано четыре набора бетонных смесей, из которых каждый набор составил 9 прямоугольных призм, которые были протестированы на изгиб на 7-й день, 14-й день и 28-й день на 3-х прямоугольных призмах. Результаты эксперимента показали, что добавление рубленой фибры повысило прочность бетонной призмы на изгиб. 1,5% фибра дала наилучшую прочность на изгиб как в базальтобетоне, так и в стальном армированном фиброй бетоне. Базальтобетон показал большую пластичность с меньшим количеством трещин, чем стальной фибробетон.
Ключевые слова: базальтовое волокно, стальное волокно, прочность на изгиб, армированный фибробетон, армированный волокнами.
