Degradation of Glass Fiber Reinforced Concrete Due to Environmental EffectsSmita SinghDegradation of Glass Fiber Reinforced Concrete Due to Environmental Effects2Table of Contents Introduction Fiber Reinforced Polymer Composite Glass Fiber Reinforcement GFRP Composite vs. Steel Reinforced Concrete Deleterious effects of several environments on fibers and matrices EnvironmentalDeformations of GREP barsDegradation of tensile strengt!Direct s!ear capacityPredicted deflections due to creep"ond be!avior and development lengt!Effects of t!ermal e#pansion on crac$ing of FRP reinforced concreteDegradation of Glass Fiber Reinforced Concrete Due to Environmental Effects3T!e use of glass fiberreinforced polymer %GFRP& composites is becoming increasingly common in construction' bot! in ne( construction and in t!e repair of deteriorated structures."enefits of GFRPs are (ellrecogni)ed* !ig! strengt!(eig!t ratio' corrosion and fatigue resistance+ ease of !andling' and ease of fabrication.T!e mec!anical properties of a !ybrid material system may deteriorate muc! faster t!an t!at suggested by t!e property degradation rates of t!e individual components ma$ing up t!e !ybrid system.T!ere is a need to ma$e analysis on t!e mec!anical properties of GFRP (!en e#posed to environmental conditions IntroductionDegradation of Glass Fiber Reinforced Concrete Due to Environmental Effects4, composite is a mi#ture of t(o or more p!ases %materials&. FRP is a t(o p!ase composite constituting of matri# and reinforcement.-atri# *It is the continuous phase and surrounds the reinforcements. It is made from polymer. Bind the reinforcements (fibers/particulates) togetherTransfer load to the reinforcementsProtect the reinforcements from surface damage due to abrasion or chemicalattacks.Reinforcement * The term reinforcement! implies some property enhancement. It is the dispersed phase" #hich normally bears the ma$ority of stress.%ifferent types of &ibres or&ilaments are continuous or discontinuous fibres .Fiber Reinforced Polymer Composite Degradation of Glass Fiber Reinforced Concrete Due to Environmental Effects5 Glass fiberreinforced polymer composites %GFRPs&' (ost common fiber used' )igh strength' *ood #ater resistance' *ood electric insulating properties' +o# stiffness. Carbon fiberreinforced polymer composites %CFRPs&' *ood modulus at high temperatures' ,-cellent Siffness' (ore ,-pensi.e than glass' Brittle' +o# electric insulating properties ,ramid fiberreinforced polymer composites %,FRPs&'Superior resistance to damage (energy absorber)' *ood in tension applications (cables" tendons)' (oderate Stiffness' (ore ,-pensi.e than glass Types of Fiber Reinforced Polymer Composite Degradation of Glass Fiber Reinforced Concrete Due to Environmental Effects6Properties .f Continuous and ,ligned GFRP' CFRP' ,FRP/ psi 0 1.234$PaDegradation of Glass Fiber Reinforced Concrete Due to Environmental Effects7Glass Fiber Reinforcements *lass fiber reinforcements are classified according to their properties. A-glass is a high-alkali glass containing 25% soda and lime, which offers very good resistance to chemicals, !t lower electrical "ro"erties# $-glass is chemical glass, a s"ecial mi%t!re with e%tremely high chemical resistance# &-glass is electrical grade with low alkali content# 't manifests etter electrical ins!lation and strongly resists attack y water# (ore than 5)% of the glass fiers !sed for reinforcement is &-glass#*-glass is a high-strength glass with a 33% higher tensile strength than &-glass#+-glass has a low dielectric constant with s!"erior electrical "ro"erties# ,owever, its mechanical "ro"erties are not so good as &-or *-glass# 't is availale in limited -!antities# Degradation of Glass Fiber Reinforced Concrete Due to Environmental Effects.Tensile StrengthGFRP bars have higher strength, than the specified yield strength fy of steel reinforcing bars. -odulus of ElasticityGlass Fiber reinforced polymer (GFRP) bars have lowermodls of elasticity than steel bars . !ence limited tensile strength is sed to control widthof crac"s intension #one at service .Creep and S!rin$ageCreep and s!rin$age be!avior in GFRPreinforced members is similar to t!at in steelreinforced members.GFRP vs. Steel Reinforced Concrete Degradation of Glass Fiber Reinforced Concrete Due to Environmental Effects/S!ear Strengt!T!e concrete contribution to s!ear strengt! is reduced inbeams (it! GFRP longitudinal reinforcement because of smaller concrete compression )ones and (ider crac$s C!emical ,ttac$GFRP bars are noncorrosive andnonreactive to c!lorides. T!ey e#perience a loss of strengt! (it! time' particularly in an al$aline environment StressStrain "e!aviorT!e stressstrain be!avior of GFRP bars is linear elastic to failure' (it! no yield plateau. T!ermal Conductivity GFRP materials !ave relatively lo(er t!ermal conductivity t!an steel (/ontd.)GFRP vs. Steel Reinforced ConcreteDegradation of Glass Fiber Reinforced Concrete Due to Environmental Effects0)Deleterious effects of several environments on fibers and matricesWater$ Polymeric fibers and matrices absorb moisture. (oisture absorption softens the polymers Weak acids1 Bridges in industriali0ed areas may be e-posed to #eak acids from acid rain and carboni0ation" #ith p) .alues bet#een 1 and 2. 3eak acids can attack glass fiber sand polyester matrices.Strong acids1 4ccidental spillage may cause strong acids to come in contact #ith bridge components. Strong acids can attack glass fibers" aramid fibers and polyester and epo-y matrices.Weak alkalis1 /oncrete containing po00olanas can ha.e p) .alues bet#een 2 and 56. 3eak alkalis can attack glass fibers and polyester matrices.Degradation of Glass Fiber Reinforced Concrete Due to Environmental Effects00Deleterious effects of several environments on fibers and matricesStrong alkalis1 Typical portland cement concretes ha.e p) .alues greater than 56 and can cause degradation of glass fibers. Strong alkalis can attack glass fibers" aramid fibers" and polyester matrices#High temperatures1 Carbon and glass fibers are resistant to !ig! temperatures. 5o(ever' !ig! temperatures adversely affect aramid fibers and polymeric matrices.Ultraviolet radiation1 Carbon and glass fibers are resistant to ultraviolet radiation. 5o(ever' ultraviolet radiation adversely affects aramid fibers and polymeric matrices.Degradation of Glass Fiber Reinforced Concrete Due to Environmental Effects02Time Dependent Deformations of GREP bars%egradation of tensile strength%irect shear capacityPredicted deflections de to creep&ond behavior and development length'ffects of thermal e(pansion on crac"ing of FRP reinforced concreteDegradation of Glass Fiber Reinforced Concrete Due to Environmental Effects03For determining time dependent deformations of GREP bars' e#perimental analysis (as done.Specifications of GFRP Reinforcing "ars used*GFRP bars pro.ided by threedifferent manufacturers #ere used in the e-periments The bars are identified as bar P" 75" and 78. Environmental Deformations of GREP barsDegradation of Glass Fiber Reinforced Concrete Due to Environmental Effects04Degradation of tensile strengt!The tensile strength of *&9P bars degrades #ith time #hile in contact #ith simulated concrete pore solution (alkaline) .The o.erall a.erage tensile strength reductions #ere 5 percent at 8: #eeks and 2 percent at ;6 #eeks Degradation of Glass Fiber Reinforced Concrete Due to Environmental Effects05 +arger shear strength degradations are e-pected to occur in *&9P bars e-posed to high p) solutions Bar types P" 75" and 78 #ere e-posed to different alkaline and chloride for ;5" 25" and 25 #eeks respecti.ely. *&9P bars #ere tested at a constant load rate in direct shear.Direct s!ear capacityDegradation of Glass Fiber Reinforced Concrete Due to Environmental Effects06Predicted deflections due to creep /reep can be defined as the increase in length of a bar loaded #ith a constant force o.er time" beyond the initial (elastic) deformation.&rom e-perimental results it #as obser.ed that *&9P bars can creep bet#een 8 and : percent o.er si- months" #hen stressed at about 8< percent of the ultimate strength of the bar.Degradation of Glass Fiber Reinforced Concrete Due to Environmental Effects07"ond be!avior and development lengt!A set of s"ecimens was e%"osed o!tdoors and another set was e%"osed indoors !nder high tem"erat!re and high h!midity conditions# for a "eriod of 06 months 2es!lts indicate that a contin!o!sly wet concrete environment may degrade the ond "ro"erties of 3425 ars more than an o!tdoor e%"os!re, y as m!ch as 3) "ercent after 06 months of e%"os!re# Any ond strength degradation increases the re-!ired develo"ment length of a reinforcing ar ,verage slip at loaded end of 6.4 in. diameter bars at failureDegradation of Glass Fiber Reinforced Concrete Due to Environmental Effects0.Effects of t!ermal e#pansion on crac$ing of GFRP reinforced concrete The setting temperature of the specimens #as assumed to occur at =; >& (/). The e-perimental results indicated that a typical ? in. thick concrete bridge deck reinforced #ith *&9P bars #ould not e-perience cracking on the surface due to thermal e-pansion for concrete co.ers of 5" 8" and < in. and *&9P reinforcement #ith a diameter 6.2; in. or smaller for conditions #here a temperature rise @ than ;1 >&(5< >/)from the concrete setting temperature takes place.Degradation of Glass Fiber Reinforced Concrete Due to Environmental Effects0/Conclusion*&9P composites ha.e many e-cellent structural Aualities and some e-amples are high strength to #eight ratio" material toughness" and fatigue endurance. Bther highly desirable Aualities are high resistance to ele.ated temperature" abrasion" corrosion" and chemical attack. But its degradation due to en.ironmental conditions are needed to be considered #hile designing of *&9P reinforced concrete elements.Degradation of Glass Fiber Reinforced Concrete Due to Environmental Effects2)6hank 7o!