This paper presents a comprehensive experimental investigation to explore the effect of synthetic and natural fibers, both individual and hybrid, on the strength properties and impact resistance of concrete exposed to different elevated temperatures (27, 200, 400, and 800 C). The influence of steel, polypropylene, and sisal fibers on compressive strength and impact resistance under the elevated temperature was investigated, and a comparison was made with conventional concrete. Apart from mono-fiber reinforced concrete, the resistance of hybrid fiber reinforced concrete containing steel-polypropylene and sisal fibers in different hybrid combinations to impact loading and compressive strength was also evaluated. The results revealed that the incorporation of fibers helps in improving the mechanical properties of concrete both at ambient and elevated temperatures. Finally, this study confirms that mono steel fibers can be replaced with a hybrid mix containing natural fiber to improve concrete's residual hardened properties and fire resistance.

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Earlier the methods adopted for the repair and rehabilitation were the external bonding of the damaged component with steel fibers and steel jackets. But the major problem that caused due to this steel components is corrosion. Fiber Reinforced Polymer (FRP) composite materials used for strengthening of components in the form of confinement is of considerable importance in civil engineering. This paper presents the results of axially loaded RC short columns which are strengthened by providing confinement with new material BFRP. The primary objective of this work is to examine the load carrying capacity of concrete columns confined with basalt fiber reinforced polymer jacket (BFRP) which is considered as an abstruse material for strengthening. BFRP materials are non-corrosive, non-magnetic, and chemical resistant and they are progressively being used for repair, rehabilitation, and strengthening of structures that are not stable enough to carry loads. The parameters considered in the study are full and partial wrapping and the number of layers of confinement. The results obtained from the experimental studies and the analytical models precisely shows that the BFRP confinements will upgrade the compressive strength of columns under the given load condition.

In the present study, the stress-stain behaviour of confined concrete made with basalt fibre reinforced polymer bars (BFRP) were taken up. The stress-strain behaviour was studied for the concrete mixes confined with steel rebars and BFRP rebars. The confinement was given in the form of steel hoops in the cylinders, 3 hoops (0.8%), 4 hoops (1.1%), 5 hoops (1.3%) and 6 hoops (1.6%). The addition of basalt fibres along with confinement of concrete with steel and BFRP hoops enhanced the compressive strength, indicating further confinement effect in the concrete. It is observed that the addition of fibres is helpful in lower confinements only. Beyond 1.1% confinement, the addition of any type of basalt fibres doesn’t show any effect on compressive strengths. From the stress-strain behaviour of all types of concrete mixes, it is concluded that the ultimate load-carrying capacity and strains at peak stresses are more in concrete with BFRP hoops for mixes up to 1.1% confinement. The addition of basalt fibres to concrete has increased the ductility in both confined and unconfined states