STRUCTURAL APPLICATIONS OF COMPOSITES IN INFRASTRUCTURE
also being used in combination with concrete slabs to develop and test new model bridges by M. Saiidi and F. Gordaninejad at University of Nevada, Reno. Since the 1930's, glass fiber reinforced plastic (GFRP) has been considered a good substitute for steel as a reinforcement ofconcrete or to create an initial state ofcompressive stress in concrete by prestressing GFRP tendons~ Reinfofcement and prestressing of concrete are common ways to miti.gate the lo\v tensile strength of concrete in order to take advantage of its high compressive strength~ In fact, reinforced concrete is a fiber reinforced composite material in '''hieh the advantageous properties of the constituents are high tensile strength of the rebars (steel or FRP) and the high compressive strength of the concrete matrix.. Surface protection of certain types of continuous glass fibers, particularly E..glass fibers, from attacks by the environment or alkaline reaction with concrete has been accomplished by coatings, including resins. For example, a typical continuous E..glass fiber reinforced plastic rebar has a 55% glass vol.ume fraction enlbedded in a matrix ofv'inylester or isophthalic resin~ These thermoset resin systems have ex~ ceHent resistance to corrosion a.nd impact, are good electrical and thermal insulators, are easy to manufacture, and are cost effective~ Thermoplastic rebars, which are more expensive than thermosets, have a potential for reshaping and \velding in the field which motivates current investigation oftheir potential applications in constnlction# Aramid fibers (e.g#, DuPont's Kevlar® 29, 49, 149) with higher tensile strength (3~62 GPa) and stiffness (124 G·:Pa for Kevlar@ 49) than glass fibers are being used to devel.op high strength rebars and cables by DoS. and Japanese manufac~ turerso AraIuid fibers have good chemical resistance to sol .. vents, dilute ac...i.ds~ and bases, as well a..1O) excellent fatigue strength and low relaxationo Carbon fiber reinforced plastic rebars and seven wire strands (cables) \vith higher stiffness than glass or aramid fiber rehars are also manufactured as reinforcing or prestressing eleluents for structural appHca~ tions, Ho\vever, carbon fiber rebars and cables are even more expensive than aramid or glass rebars, Chopped fiber rein-· forced plastic rods are being manufactured by extrusion~ 'fhesr.
A review on FRP composites applications and durability concerns in the construction sector
Construction sector is one of the largest markets for fibre reinforced polymers (FRPs) globally. FRP composites are used in a wide range of applications in construction ranging from rehabilitation of existing structures to the full-scale use for new projects because of the benefits they provide over conventional building materials. Such advantages include but not limited to lightness, high mechanical performance and possibility of production in any shape, ease of installation and lesser requirement for supporting structure, controlled anisotropy, high specific strength and specific stiffness. All these multifarious features of FRPs are knocking the doors for new avenues of myriad applications in the Construction Industry, but unfortunately polymeric composites are susceptible to heat and moisture when operating in changing environmental conditions dispelling the biggest myth of them being invincible. The heat response of FRPs is also a major issue of importance in dictating the fate of FRPs future acceptability and applicability. This paper thus attempts to review the specific areas of the current utilization trend of FRPs in the Construction Industry and draw their advantages to support the future applications in a variety of construction processes. It is also being attempted to juxtapose the applicability and the durability concerns of FRPs in a single literature for assessing the versatility and scope of FRPs, by shedding light on the past available studies on the related matter.
Fiberglas Reinforced Plastic Rebars in Lieu of Steel Rebars
Fiberglass reinforced plastics have recently been introduced in the market in the form of rebars for concrete reinforcement. The light weight, corrosion resistance and non-magnetic properties of these rebars make them a better alternative than steel in some applications of reinforced concrete. However, the mechanical behavior of this material as reinforcing in concrete is not well known. The contributions of the reinforced plastics rebars to the flexural and shear capacities of concrete need to be defined. In this paper, the results of laboratory tests conducted on concrete beams reinforced with fiber reinforced plastic rebars, alone and in combination with steel rebars are presented. Discussion of the results and conclusions are presented at the end.