The present trend in concrete technology is towards increasing the strength and durability of concrete to meet the demands of modern construction. The aim of this paper is to study the effect of hybrid fiber (steel & polypropylene) in concrete and compare its properties with that of plain cement concrete. The findings showed that the addition of hybrid fibers to plain cement concrete improved its mechanical properties.
Crack growth due to loading and shrinkage should both be controlled in slab like concrete structures, such as pavements, runways for airports, and continuous slab-type sleepers for high-speed trains. In these types of structures, effective prestressing for crack control purposes will be very difficult, especially in the two principal directions. So, dispersed short fiber reinforcement offers a second approach in this case. The concept of hybridization with two different fibers incorporated in a common cement matrix can offer more attractive engineering properties because the presence of one fiber enables effective utilization of the potential properties of the other fibers. Optimization of mechanical and conductivity properties can be achieved by combining different types and sizes of fibers.
By embedding conventional reinforcements into concrete material, only cracks at certain structural sections and at a single scale can be arrested, although fracturing in concrete is multi-scale. Hybridization means the combination of two or more fibers with different properties in an appropriate manner to take full advantage of the resultant product. Based on the anticipated performance from the final composite material, the fiber properties to be considered are length, diameter, strength, elastic modulus, aspect ratio, specific gravity and so on. It can generally be stated that larger fibers are more effective in bridging macro cracks (providing toughness) while smaller fibers are effective in bridging micro cracks, thus enhancing the behaviour before and/or right after crack formation. With a proper combination of large and small fibers, individual benefits can be achieved simultaneously in a single hybrid cementitious composite.
II. LITERATURE REVIEW
Mohamed & Ahmed (2021): The ultimate load carrying capacity of MSFRC slabs was seen to increase by 24%, 20% and 23% for interior, edge and corner loading positions in the study conducted.
Radim & Zuzana (2020): Positive influence of fiber concrete on the increased load capacity and more favourable deformations of the slab on subsoil exposed to a vertical concentrated load was established in this study.
Mageswari et al (2018): conducted studies and showed that on comparing with steel fibers the synthetic fiber reinforced concrete provided lower impact resistance.
Jun Feng & Weiwei Sun (2018): Impact energy property of concrete discs was studied and it was seen that by the incorporation of polymer (PP/PVA) fiber or steel fiber, there was an improvement in the property.
Navilesh & Rahul (2017): conducted study and showed that the strength of hybrid fiber reinforced concrete is higher than the strength of normal concrete.
Grija et al (2016): Addition of Recon 3s fibers into concrete mixes improved the compressive strength, split tensile strength and flexural strength at 28 days for fiber mixes when compared with that of control mix.
Arunakanthi (2016): showed that on adding fiber there was a percentage increase in compressive strength, flexural strength and split tensile strength for 28 days.
Deepa et al (2014): The study concluded that steel fiber reinforced concrete is an excellent new type of composite material as thickness of road was reduced without affecting the load carrying capacity.
Nassim & Bijan (2013): The study conducted showed that adding PP fibers to concrete enhanced the toughness and energy absorption characteristics.
Jayeshkumar & Umrigar (2013): It was seen in this study that water absorption and sorptivity of fly ash concrete showed higher values than that of traditional concrete.
III. OBJECTIVES OF THE STUDY
The following are the objectives of the present work:
Evaluate the strength parameters of PCC, FRC & hybrid FRC
Compare the mechanical properties of PCC & FRC
Determine load carrying capacity and corresponding deformations in PCC & FRC slab
A. Investigations on Materials
The materials to be used in this investigation are: ordinary Portland cement, coarse aggregate, fine aggregate and potable water as well as steel and polypropylene fiber. The detailed properties are given in subsequent contents.
First and foremost, I would like to thank the ALMIGHTY GOD who blessed me to overcome all the obstacles I came across while proceeding with this project. I take immense pleasure in taking Dr. Manju. J, Principal, Mahaguru Institute of Technology, Pallickal P.O, Mavelikara for having permitted me to carry out this project. I wish to express my sincere thanks to my project guide Prof. Priya Grace Itti Eipe, Head of the Department of Civil Engineering for her excellent encouragements in course of this work. I take immense pleasure in conveying my thanks and deep sense of gratitude to my project coordinator Mrs. Suji. P, Assistant Professor, Department of Civil Engineering for her exhilarating supervision, timely suggestions and encouragement during entire project. I would like to thank all the teaching facility members and supporting staff of our department for advising me whenever in need, co-operating with me and arranging the necessary facilities .I would like to convey my gratitude to my parents whose blessings and prayers were always there with me. Last but not the least I would like to thank my friends and others who directly or indirectly helped me in successful completion of this project.
From this present work the following conclusions can be drawn:
1) It is clear that the optimum dosages of steel and polypropylene fiber content in concrete improve the mechanical properties of concrete
2) There is a significant increase in compressive and tensile strength with the addition of steel fiber in normal concrete
3) When compared to PFRC and hybrid FRC, SFRC shows higher strength
 A.Warudkar and P.Kawde. (2017). Steel Fiber Reinforced Concrete A Review. International Journal of Engineering Sciences & Research Technology (IJESRT).
 A.Jangid and A.Sharma. (2020). Experimental Study on the Properties of Steel Fibre Reinforced Concrete. Indian Journal of Engineering.
 S.Abinaya., S.Grija and D.Shanthini. (2016). A Review on Fiber Reinforced Concrete. International Journal of Civil Engineering and Technology (IJCIET). Vol. 7.
 A.Bazgir. (2016). The Behaviour of Steel Fibre Reinforced Concrete Material and its Effect on Impact Resistance of Slabs.
 M.Ahmed and S.Mohamed. (2021). Improvement of Load Carrying Capacity of Concrete Pavement Slabs Using Macro Synthetic Fibers. https://www.mdpi.com/journal/coatings. Vol. 11.
 A.Swarup and M.Gulfam. (2017). A Review on Steel Fiber Reinforced Concrete. International Conference on Advance Studies in Engineering and Sciences (ICASES).
 N.Ameersohel, N.Basavannevva, P.Bishetti and A.Veergangadhar. (2019). Glass Fiber Reinforced Concrete. International Journal of Civil Engineering (IJCE). Vol. 6.
 E.Arunakanthi. (2016). Experimental Studies on Fiber Reinforced Concrete (FRC). International Journal of Civil Engineering and Technology (IJCIET). Vol. 7.
 B.Samali and N.Ghosni. (2015). Energy Absorption and Flexural Toughness Evaluation of Fibre Reinforced Polymer Modified Concrete. International Conference on Fracture Mechanics of Concrete and Concrete Structures. Vol. 8.
 A.Z.Chitade and R.Sandeep. (2019). A Review on Literature of Fiber Reinforced Concrete with Silica Fumes. International Conference on Innovation & Research in Engineering, Science & Technology (ICIREST).
 D.Babhu., S.Mageswari, and S.Neomi. (2018). Fibre Reinforced Concrete. International Journal of Engineering Research & Technology (IJERT). Vol. 6.
 D.Sinha., C.B.Mishra and V.Ravindra. (2014). Comparison of Normal Concrete Pavement with Steel Fiber Reinforced Concrete Pavement. Indian Journal of Applied Research. Vol. 4.
 J.Pitroda and F.S.Umrigar. (2013). Evaluation of Sorptivity and Water Absorption of Concrete with Partial Replacement of Cement by Thermal Industry Waste. International Journal of Engineering and Innovative Technology (IJEIT). Vol. 2.
 J.Feng and W.Sun. (2018). Experimental Study on Hybrid Effect Evaluation of Fiber Reinforced Concrete Subjected to Drop Weight Impacts. http://www.mdpi.com/journal/materials. Vol. 11.
 K.Gharehbaghi and R.Chenery. (2017). Fiber Reinforced Concrete (FRC) for High Rise Construction: Case Studies. IOP Conf. Series: Materials Science and Engineering.
 M.Jaral and S.Firdous. (2018). A Review Study on the Steel Fiber Reinforced Concrete Pavement. International Journal of Scientific Development and Research (IJSDR). Vol.3.
 J.Navilesh and B.Rahul. (2017). A Study on Hybrid Fiber Reinforced Concrete. International Research Journal of Engineering and Technology (IRJET). Vol. 4.
 P.Zhang., S.Han., Serina and Wang. (2018). Fiber-Reinforced Concrete with Application in Civil Engineering. Advances in Civil Engineering.
 R.Cajka and Z.Marcalikova. (2020). Experiments on Fiber Concrete Foundation Slabs in Interaction with the Subsoil. http://www.mdpi.com/journal/sustainability. Vol. 12.
 S.Shubham and S.Shrivastava. (2020). Review on Steel Fiber Enriched Reinforced Concrete. International Journal of Engineering Research and Applications (IJERA). Vol.10.