concrete is strong in compression and weak in tension.
The usage of fibres in combination with concrete also results in a mix with improved early resistance to plastic shrinkage cracking and thus, keeps the concrete from drying shrinkage cracks. For increasing the tensile and flexural strength, fibres are added in concrete. The addition of fibres to concrete will result in a complex material that has properties different from those of un-reinforced concrete. The range of this variation depends not only on the type of fibres, but also on the fibre dosage. It has been recognized that adding small, closely spaced and uniformly dispersed fibre to concrete serves to arrest cracks and improve its properties under static and dynamic loading. Alkali resistant glass fibre reinforcement is a fairly new addition to the family of fibres that impart high tensile strength, high stiffness, high chemical resistance and significant durability to FRC (Fibre Reinforced Concrete). (Ravikumar and Thandavamoorthy, 2013).
GFRC is Concrete containing alkali resistance glass fibre. To evaluate the influence of Alkali Resistant (AR) glass fibres on workability, compressive strength and flexural strength of GFRC, an experimental program was conducted.Steel fibres have been used in concrete since the early 1900’s. These fibres are available in different geometrical shapes like; straight, crimped, hooked end etc.
Modern commercially available steel fibres are manufactured from drawn steel wire, from slit sheet steel or by the melt-extraction process which produces fibres that have a crescent-shaped cross section. Steel fibre should have an ultimate tensile strength of at least 800 MPa (IS, 2013).(a) Polypropylene Fibres Portland cement concrete is considered to be a relatively brittle material. When subjected to tensile stresses, non-reinforced concrete will crack and fail. The problem with employing steel in concrete is that over time steel corrodes due to the ingress of chloride ions . More recently micro fibres, such as those used in traditional composite materials have been introduced into the concrete mixture to increase its toughness, or ability to resist crack growth. Several different types of fibres, both manmade and natural, have been incorporated into concrete. Use of natural fibres in concrete precedes the advent of conventional reinforced concrete in historical context.
The fibre reinforced concrete structure cracks at the same peak tensile load, but does not separate and can maintain a load to very large deformations.
