As a rule of thumb, small fibres tend to be used where control of crack propagation is the most important design consideration. High fibre count (number of fibres per kg) permits finer distribution of steel fibre reinforcement throughout the matrix &#; and consequently, greater crack control during drying process. On the other hand, because they exhibit better matrix anchorage at high deformations and large crack widths, longer, heavily deformed fibres afford better post-crack "strength". However, unlike shorter fibres, the dramatically reduced fibre count of longer product yields correspondingly less control of initial crack propagation.
Goto well to know more.
&#;
When steel fibres are added to mortar, Portland cement concrete or refractory concrete, the flexural strength of the composite is increased from 25% to 100% - depending on the proportion of fibres added and the mix design. Steel fibre technology actually transforms a brittle material into a more ductile one. Catastrophic failure of concrete is virtually eliminated because the fibres continue supporting the load after cracking occurs. And while measured rates of improvement vary, Steel fibre reinforced concrete exhibits higher post-crack flexural strength, better crack resistance, improved fatigue strength, higher resistance to spalling, and higher first crack strength, Figure 2 shows concrete flexural strengths when reinforced at various fibre proportions. Additionally, deformed fibres provide a positive mechanical bond within the concrete matrix to resist pull-out. Steel fibres are available in lengths from 38 mm to 50 mm and aspect ratios between 40 and 60. The fibres are manufactured either deformed or hook end, and conform to ASTM A-820.
&#;
Conventional practice usually concentrates welded wire fabric reinforcement within a single plane of a floor slab. Fabric does very little to reinforced the outer zones, which is why spalling is common at the joints and edges. The primary function of welded wire fabric is to hold the floor slab together after the first small hairline cracks have propagate to larger fractures. This serves to maintain some degree of "structural integrity". Conventional wisdom&#;s approach to floor slabs is to maintain "material integrity" through SFRC mix designs. This integrity is accomplished by:
&#;
&#;
&#;
Industrial Ground Floor Slabs &#; Warehouses, Factories, Aircraft Hangers, Roads, Bridge Decks, Parking Areas, Runways, Aprons and Taxiways, Commercial and Residential Slabs, Piling, Shotcrete, Tunnels, Dams and stabilisation.
&#;
Steel fibre reinforced concrete is a castable or sprayable composite material of hydraulic cements, fine, or fine and coarse aggregates with discrete steel fibres of rectangular cross-section randomly dispersed throughout the matrix. Steel fibres strengthen concrete by resisting tensile cracking. Fibre reinforced concrete has a higher flexural strength than that of unreinforced concrete and concrete reinforced with welded wire fabric. But unlike conventional reinforcement &#; which strengthens in one or possibly two directions &#; Steel fibres reinforce iso tropically, greatly improving the concrete&#;s resistance to cracking, fragmentation, spalling and fatigue. When an unreinforced concrete beam is stressed by bending, its deflection increases in proportion with the load to a point at which failure occurs and the beam breaks apart. This is shown in Figure 1. Note that the unreinforced beam fails at point A and a deflection of B. A Steel fibre reinforced beam will sustain a greater load before the fist crack occurs (point C). It will also undergo considerably more deflection before the beam breaks apart (point D). The increased deflection from point B to point D represents the toughness imparted by fibre reinforcement. The load at which the first crack occurs is called the "first crack strength". The first crack strength is generally proportional to the amount of fibre in the mix and the concrete mix design.
Two theories have been proposed to explain the strengthening mechanism. The first proposes that as the spacing between individual fibres become closer, the fibres are better able to arrest the propagation of micro cracks in the matrix. The second theory holds that the strengthening mechanism of fibre reinforcement relates to the bond between the fibres and the cement. It has been shown that micro cracking of the cement matrix occurs at very small loads. Steel fibres, then service as small reinforcing bars extending across the cracks. So as long as the bond between the fibres and cement matrix remains intact the Steel fibres can carry the tensile load. The surface area of the fibre is also a factor in bond strength. Bond strength can also be enhanced with the use of deformed fibres, which are available in a variety of sizes.
&#;
The proportions of Steel fibres in mix designs usually range from 0.2% to 2.0% (15 to 150 kg/m3 ) of the composite&#;s volume. Key factors to consider largely depend on the application under consideration and/or the physical properties desired in the finished project. Mix designs with fibre proportions above 60kg/m3 are usually adjusted to accommodate the presence of millions of steel fibre reinforcing elements. The adjustments are an increase in the cement factor, a reduction in the top size of the coarse aggregate and the addition of a super plasticiser. Prototype testing is recommended to determine the optimum design for each application.
&#;
&#;
ORIGINAL ARTICLE
KEYWORDS
ABSTRACT
Concrete possesses distinct features that make it widely acceptable for use across the globe; however, along with its obvious benefits, it has numerous drawbacks i.e., it is brittle in nature and its production causes an adverse impact on the environment. To counter such problems, researchers around the world have introduced sustainable measures. Fibre addition is foremost among these solutions in that it prevents crack propagation and increases the overall strength of concrete. In the present age, civil engineering structures have their own structural and durability requirements and so, modification in traditional concrete has become a necessity. This research is targeted at steel fibre reinforced concrete (SFRC), which is a superior quality concrete because of its enhanced strength. The steel fibres are obtained from binding wire that is used to tie the steel reinforcement. By referring to past research, steel fibres with an aspect ratio (length to diameter ratio) of 30 were considered favourable. The controlled, mixed design of the concrete was prepared with a targeted strength of psi and, while mixing the concrete ingredients, fibres were added to allow uniform dispersion. The fresh and hardened properties of workability, compressive, and tensile strength were tested and the results of fibres at 0%, 1%, 2% and 3% concrete mass were compared and analysed. The results indicated that highest compressive and tensile strength values were achieved with 3% fibre addition. However, with further addition, it was observed that concrete loses its workability. Therefore, it is suggested that 1% addition of steel fibres produces good strength with sufficient workability.
REFERENCES
(34)
1.
Sukumar, A and John, E . Fiber addition and its effect on concrete strength. International Journal of Innovative Research in Advanced Engineering 1(8), 144&#;149.
2.
Raza, MS, Rai, K, Kumar, D and Ali, M . Experimental study of physical, fresh-state and strength parameters of concrete incorporating wood waste ash as a cementitious material. Journal of Materials and Engineering Structures 7, 267&#;276.
3.
Zhang, J, Liu, G, Chen, B, Song, D, Qi, J and Liu, X . Analysis of CO 2 emission for the cement manufacturing with alternative raw materials: A LCA-based framework. Energy Procedia 61, &#;.
4.
Mangi, SA et al. . A review on potential use of coal bottom ash as a supplementary cementing material in sustainable concrete construction. International Journal of Integrated Engineering 10, 127&#;135.
5.
Sandhu, AR, Rind, TA, Kalhoro, SA, Lohano, R and Laghari, FH . Effect on the compressive strength of mortars using ground granulated blast furnace slag as a partial replacement of cement. Journal of Applied Engineering Sciences 9, 183&#;186.
6.
Neville, AM and Brooks, JJ . Properties of concrete.
7.
Mangi, SA, Jamaluddin, N, Wan Ibrahim, MH, Mohamad, N and Sohu, S . Utilization of sawdust ash as cement replacement for the concrete production: A review. Engineering Science and Technology International Research Journal 1, 11&#;14.
8.
Mangi, SA, Jamaluddin, NB, Siddiqui, Z, Memon, SA and Bin Wan Ibrahim, MH . Utilization of sawdust in concrete masonry blocks: A review. Mehran University Research Journal of Engineering & Technology 38, 487&#;494.
9.
Mangi, SA, Ibrahim, MHW, Jamaluddin, N, Arshad, MF and Mudjanarko, SW . Recycling of coal ash in concrete as a partial cementitious resource. Resources 8, 1&#;10.
10.
Agarwal, A, Nanda, B and Maity, D . Experimental investigation on chemically treated bamboo reinforced concrete beams and columns. Construction and Building Materials 7, 610&#;617.
11.
Kawde, P and Warudkar, A . Steel fiber reinforced concrete: A review. International Journal of Engineering Science and Research & Technology 6, 130&#;133.
12.
Okeola, AA, Abuodha, SO and Mwero, J . Experimental investigation of the physical and mechanical properties of sisal fiber-reinforced concrete Fibers 6, 1&#;16.
For more information, please visit Construction Steel Fiber.
13.
Kandasamy, R and Murugesan, R . Fiber reinforced concrete using domestic waste plastics as fibres. ARPN Journal of Engineering Applied Sciences, 75&#;82.
14.
Paris, JM, Roessler, JG, Ferraro, CC, Deford, HD and Townsend, TG . A review of waste products utilized as supplements to Portland cement in concrete. Journal of Cleaner Production 121, 1&#;79.
15.
Bheel, N, Awoyera, P, Aluko, O, Mahro, S, Viloria, A and Sierra, CAS . Sustainable composite development: Novel use of human hair as fiber in concrete. Case Studies in Construction Materials 13.
16.
Meghwar, SL, Khaskheli, GB and Kumar, A . Human Scalp Hair as Fiber Reinforcement in Cement Concrete. Mehran University Research Journal of Engineering & Technology 39, 443&#;452.
17.
Wan Ibrahim, MH et al. . Compressive and flexural strength of concrete containing palm oil biomass clinker and polypropylene fibres, in: IOP Conf. Ser. Mater. Sci. Eng.
18.
Nishane, UR and Thakare, NU . Experimental studies on fiber reinforced concrete (FRC). Int. Journal of Engineering Research Application 7, 40&#;44.
19.
Ranyal, A and Kamboj, J . Effect of addition of different type of steel fibres on the mechanical aspects of concrete - A review. International Journal of Civil Engineering and Technology 7, 33&#;42.
20.
Karththekeyan, T and Baskaran, K . Experimental study on steel fibre reinforced concrete for G-30 concrete, in: 2nd Int. Moratuwa Eng. Res. Conf. MERCon , 272&#;276.
21.
Shweta, P and Kavilkar, R . Study of flexural strength in steel fibre reinforced concrete. International Journal of Recent Development in Engineering and Technology 2, 13&#;16.
22.
Behbahani, HP, Nematollahi, B and Farasatpour, M . Steel fiber reinforced concrete, in: ICSECM , SriLanka.
23.
Rao, MM, Chowhan, LN and Patro, SK . Effect of aspect ratio of fiber in HDPE reinforced concrete. International Journal of Engineering Research and Technology 8, 164&#;171.
24.
Yusof, MA et al. . Mechanical properties of hybrid steel fibre reinforced concrete with different aspect ratio. Australian Journal of Basic and Applied Sciences 5, 159&#;166.
25.
Neves, RD and De Almeida, JCOF . Compressivebehaviour of steel fibre reinforcedconcrete. Structural Concrete 6, 1&#;8.
26.
Dewangan, R, Khare, GP and Sahu, P . Influence of variation of length and dosage of nylon fiber on compressive and split tensile strength of concrete. International Research Journal of Engineering and Technology 6, &#;.
27.
ASTM C150 / C150M-19a, Standard Specification for Portland Cement, ASTM International, West Conshohocken, PA, () 1&#;10.
28.
ASTM C / CM - 18 Standard Specification for Mixing Water Used in the Production of Hydraulic Cement Concrete, (n.d.). https://www.astm.org/Standards... (accessed March 23, ).
29.
Naganathan, S and Mustapha, KN . Effect of water temperature on concrete properties. Jordan Journal of Civil Engineering 9, 292&#;302.
30.
ASTM C192 / C192M - 19 Standard Practice for Making and Curing Concrete Test Specimens in the Laboratory, (n.d.). https://www.astm.org/Standards... (accessed March 24, ).
31.
ASTM C143 / C143M - 15a Standard Test Method for Slump of Hydraulic-Cement Concrete, (n.d.). https://www.astm.org/Standards... (accessed March 24, ).
32.
Jhatial, AA, Sohu, S, Bhatti, N, Lakhiar, MT and Oad, R . Effect of steel fibres on the compressive and flexural strength of concrete. International Journal of Advances in Applied Sciences 5, 16&#;21.
33.
BS EN -3: - Testing hardened concrete. Compressive strength of test specimens, (n.d.). https://shop.bsigroup.com/Prod... (accessed March 24, ).
34.
ASTM C496 / C496M - 17 Standard Test Method for Splitting Tensile Strength of Cylindrical Concrete Specimens, (n.d.). https://www.astm.org/Standards... (accessed March 24, ).
If you are looking for more details, kindly visit Refractory Stainless Steel Fiber.