Inclusions have been used since prehistoric times to improve soil.The use of strawtoimprove the quality of adobe bricks dates back to earliest human history.Many primitivepeopleused sticks andbranches toreinforcemuddwellings.Duringthe17th and 18thcenturies,French settlers alongtheBayofFundyinCanada used sticks toreinforcemuddikes. Some other early examples of man-made soil reinforcement include dikes of earth andtree branches, which have been used in China for at least 1,o00 years (e.g., western portion ofthe Great Wall)and along the Mississippi River in the 1880s.Other examples includewooden pegs used for erosion and landslide control in England, and bamboo or wire mesh,used universally for revetment erosion control.Soil reinforcing can also be achieved byusing live plant roots.The modern methods of soil reinforcement for retaining wall construction were pioneered bythe French architect and engineer Henri Vidal in the early 1960s.His research led to theinvention and development of Reinforced Earth,a system in which steel strip reinforcementis used. The first wall to use this technology in the United States was built in 1972 onCalifornia State Highway 39, northeast of Los Angeles.Today,MSE walls are the wall ofchoice in most fill situations, and MSE walls are used extensively in the U.S. and worldwide.The highest permanent wall constructed in the United States is on the order of 150 ft (46 m)with an exposed height of approximately135ft (41 m).Since the introduction of Reinforced Earth, several other proprietary and nonproprietarysystems have been developed and used.Table 1-1 provides a partial summary of some of thecurrent systems by proprietaryname,reinforcementtype,and facing system.There are many available systems,as well as new systems that continue to be introduced intothe market.Components, engineering details, system quality controls, etc.vary with eachsystem. States, therefore, need a process to sort and evaluate MSE wall systems for potentialpre-approval for use on their projects.The Highway Innovative Technology EvaluationCenter (HITEC)providesreviewand evaluation of MSEwalls.HITECwas established in1994 within the American Society of Civil Engineers (ASCE)organization.HITEC'spurpose is to accelerate the introduction of technological advances in products, systems,services, materials, and equipment to the highway and bridge markets.The evaluation ofnew and more cost-effective retaining wall systems is performed through HITEC'snationally-focused, earth retaining system (ERS) group evaluation program. The publishedreports providereviews of design,construction,performance,and quality assuranceinformation provided by the wall system suppliers with respect to conformance with thestate-of-practice criteria as outlined in the HITEC Protocol.Wall system suppliers areencouraged to conduct an independentreview of newly developed components and/orsystems related to materials,design,construction,performance,and quality assurance.SomeFHWA NHI-10-0241-Introduction1-6MSE Walls and RSS-VolINovember2009
Inclusions have been used since prehistoric times to improve soil. The use of straw to improve the quality of adobe bricks dates back to earliest human history. Many primitive people used sticks and branches to reinforce mud dwellings. During the 17th and 18th centuries, French settlers along the Bay of Fundy in Canada used sticks to reinforce mud dikes. Some other early examples of man-made soil reinforcement include dikes of earth and tree branches, which have been used in China for at least 1,000 years (e.g., western portion of the Great Wall) and along the Mississippi River in the 1880s. Other examples include wooden pegs used for erosion and landslide control in England, and bamboo or wire mesh, used universally for revetment erosion control. Soil reinforcing can also be achieved by using live plant roots. The modern methods of soil reinforcement for retaining wall construction were pioneered by the French architect and engineer Henri Vidal in the early 1960s. His research led to the invention and development of Reinforced Earth®, a system in which steel strip reinforcement is used. The first wall to use this technology in the United States was built in 1972 on California State Highway 39, northeast of Los Angeles. Today, MSE walls are the wall of choice in most fill situations, and MSE walls are used extensively in the U.S. and worldwide. The highest permanent wall constructed in the United States is on the order of 150 ft (46 m) with an exposed height of approximately 135 ft (41 m). Since the introduction of Reinforced Earth®, several other proprietary and nonproprietary systems have been developed and used. Table 1-1 provides a partial summary of some of the current systems by proprietary name, reinforcement type, and facing system. There are many available systems, as well as new systems that continue to be introduced into the market. Components, engineering details, system quality controls, etc. vary with each system. States, therefore, need a process to sort and evaluate MSE wall systems for potential pre-approval for use on their projects. The Highway Innovative Technology Evaluation Center (HITEC) provides review and evaluation of MSE walls. HITEC was established in 1994 within the American Society of Civil Engineers (ASCE) organization. HITEC’s purpose is to accelerate the introduction of technological advances in products, systems, services, materials, and equipment to the highway and bridge markets. The evaluation of new and more cost-effective retaining wall systems is performed through HITEC’s nationally-focused, earth retaining system (ERS) group evaluation program. The published reports provide reviews of design, construction, performance, and quality assurance information provided by the wall system suppliers with respect to conformance with the state-of-practice criteria as outlined in the HITEC Protocol. Wall system suppliers are encouraged to conduct an independent review of newly developed components and/or systems related to materials, design, construction, performance, and quality assurance. Some FHWA NHI-10-024 1 – Introduction MSE Walls and RSS – Vol I 1 – 6 November 2009
public agencies,especially state DOTs, requireHITEC evaluations or independentevaluations of wall components or wall systems, and obtaining such reviews has provenbeneficial to wall system suppliers in securing acceptance of their system.Currently, most process patents covering soil-reinforced system construction or componentshave expired, leading to a proliferation of available systems or components that can beseparately purchased andd assembled by theerectingcontractor.The combination ofcomponents needs to be evaluated to assure compatibility with respect to longevity,constructability, and connection strength.The remaining patents in force generally coveronlythemethod of connection between the reinforcement and thefacingIn the United States, a segmental precast facing unit 20 to 25 f2 (2 to 2.25 m2) generallysquare in shape is the facing unit ofchoice.More recently,larger precast units ofup to 50 f?(4.6m)havebeenusedandarebecomingmorecommonplace.Additionally,smallerdry-cast concrete masonry units are being used, generally in conjunction with geosyntheticreinforcementsTable 1-l. Summary of Reinforcement and FaceDetails for MSE Wall Systems.Typical Face Detail'System NameReinforcement DetailStabilized Earth WallGalvanized welded steel wire mesh withPrecast concrete panels 5 ft x 5 ft x 6 in.T&B Structural Systems LLCW7 to W20 bars. Mesh width and spacingthick or 5 ft x 10 ft x 6 in. thick. Different6800 Manhattan Blvd, Suite 304y.Epoxy-coated meshes alsosize panels used at top and bottom tocan vary.Ft. Worth Texas 76120available.match project requirements.Reinforced EarthaRibbed galvanized steel strips, 0.157 inCruciform and square shaped precastThe Reinforced Earth Companythick, 2 in. wide. Or galvanized steelconcrete nominally5 ft x5ft x5.0 to5.58614 Westwood Center Driveladder strips, W10 wire, two longitudinalin.thick. Also rectangular shaped precastSuite 1100concrete nominally 5 ff x 10 ft x 5.5 in.wires and cross bars spaced at 6 inVienna, VA 22182-2233thick. Variable height panels used at topand bottom ofwall.Retained Earth*Rectangular grid of W11, W15 or W20Hexagonal and square precast concrete 5The Reinforced Earth Companygalvanized steel wire, 24 x 6 in. grid. 2, 4,ft x 5 ft x 5.5 in. thick. Also rectangular5 or 6 longitudinal bars.8614 Westwood Center DriveStainless steelshaped precast concrete 5 ff x 10 ft x 5.5Suite 1100mesh used in marine and corrosivein, thick.Variable height panels used atVienna, VA 22182-2233top and bottom of wall.environmentMechanically Stabilized EmbankmentRectangular grid of W11, W15,and W20Precast concrete, 5 ft square, 6 in. thick.California Dept.of Transportationgalvanized welded wire mats, 6180130Streetlongitudinal wires with variable transverseP.O. Box 168041spacing.Sacramento,CA95816ARESHDPE GeogridPrecast concrete panel; rectangular 9 ffTensar Intermational Corporationwide, 5 ft high, 5.5 in. thick.5883 Glenridge Drive, Suite 200Atlanta,GA30328Wire Faced Wall4 ft wide welded steel wire mesh. Mesh isWelded steel wire mesh facing, SeveralT&B Structural Systems LLC8in.x12,18or24in.,ofW4.5toW20veneer facing options available.6800 Manhattan Blvd, Ste 304bars. Size and configuration are variable.Ft. Worth Texas 76120FHWA NHI-10-0241-Introduction1-7MSEWalls andRSS-VolINovember2009
public agencies, especially state DOTs, require HITEC evaluations or independent evaluations of wall components or wall systems, and obtaining such reviews has proven beneficial to wall system suppliers in securing acceptance of their system. Currently, most process patents covering soil-reinforced system construction or components have expired, leading to a proliferation of available systems or components that can be separately purchased and assembled by the erecting contractor. The combination of components needs to be evaluated to assure compatibility with respect to longevity, constructability, and connection strength. The remaining patents in force generally cover only the method of connection between the reinforcement and the facing. In the United States, a segmental precast facing unit 20 to 25 ft2 (2 to 2.25 m2 ) generally square in shape is the facing unit of choice. More recently, larger precast units of up to 50 ft2 (4.6 m2 ) have been used and are becoming more commonplace. Additionally, smaller drycast concrete masonry units are being used, generally in conjunction with geosynthetic reinforcements. Table 1-1. Summary of Reinforcement and Face Details for MSE Wall Systems. System Name Reinforcement Detail Typical Face Detail1 Stabilized Earth Wall Galvanized welded steel wire mesh with Precast concrete panels 5 ft x 5 ft x 6 in. T&B Structural Systems LLC W7 to W20 bars. Mesh width and spacing thick or 5 ft x 10 ft x 6 in. thick. Different 6800 Manhattan Blvd, Suite 304 can vary. Epoxy-coated meshes also size panels used at top and bottom to Ft. Worth Texas 76120 available. match project requirements. Reinforced Earth® Ribbed galvanized steel strips, 0.157 in. Cruciform and square shaped precast The Reinforced Earth Company thick, 2 in. wide. Or galvanized steel concrete nominally 5 ft x 5 ft x 5.0 to 5.5 8614 Westwood Center Drive ladder strips, W10 wire, two longitudinal in. thick. Also rectangular shaped precast Suite 1100 Vienna, VA 22182-2233 wires and cross bars spaced at 6 in. concrete nominally 5 ft x 10 ft x 5.5 in. thick. Variable height panels used at top and bottom of wall. Retained Earth The Reinforced Earth Company 8614 Westwood Center Drive Suite 1100 Vienna, VA 22182-2233 Rectangular grid of W11, W15 or W20 galvanized steel wire, 24 x 6 in. grid. 2, 4, 5 or 6 longitudinal bars. Stainless steel mesh used in marine and corrosive environments. Hexagonal and square precast concrete 5 ft x 5 ft x 5.5 in. thick. Also rectangular shaped precast concrete 5 ft x 10 ft x 5.5 in. thick. Variable height panels used at top and bottom of wall. Mechanically Stabilized Embankment California Dept. of Transportation 1801 30th Street P.O. Box 168041 Sacramento, CA 95816 Rectangular grid of W11, W15, and W20 galvanized welded wire mats, 6 longitudinal wires with variable transverse spacing. Precast concrete; 5 ft square, 6 in. thick. ARES HDPE Geogrid Precast concrete panel; rectangular 9 ft Tensar International Corporation 5883 Glenridge Drive, Suite 200 Atlanta, GA 30328 wide, 5 ft high, 5.5 in. thick. Wire Faced Wall T&B Structural Systems LLC 6800 Manhattan Blvd, Ste 304 Ft. Worth Texas 76120 4 ft wide welded steel wire mesh. Mesh is 8 in. x 12, 18 or 24 in., of W4.5 to W20 bars. Size and configuration are variable. Welded steel wire mesh facing. Several veneer facing options available. FHWA NHI-10-024 1 – Introduction MSE Walls and RSS – Vol I 1 – 7 November 2009
Typical Face Detail'SystemNameReinforcementDetailWelded Wire WallWelded steel wire mesh, Galvanized orWelded steel wire mesh,2'tall x 8" wideHilfiker Retaining WallsNon-Galvanized. Mesh reinforcementstypical, Backing mat, Hardware Cloth or1902 Hilfiker Lanevary in spacing and gauges to meet projectFilter Fabric depending on project. (WithEureka, CA 95503design specifications.geotextile or shotcrete, if desired).Reinforced Soil EmbankmentPrecast concrete unit 12.5 f long, 24 inWelded steel wire mesh, Galvanized orHilfiker Retaining WallsNon-Galvanized. Mesh reinforcementshigh.1902 Hilfiker Lanevary in spacing and gauges to meet projectEureka, CA 95503design specifications.ArtWeld GabionsWelded steel wire mesh, Galvanized orArWeld Gabion baskets of various sizesHilfiker Retaining WallsNon-Galvanized. Mesh reinforcementsand heights designed per project1902 Hilfiker Lanevary in spacing and gauges to meet projectrequirements.Eureka, CA 95503design specifications.Gabion Faced M.S.E.Welded steel wire mesh, Galvanized orArtWeld Gabions of various sizes andHilfiker Retaining WallsNon-Galvanized. Mesh reinforcementsheights connected to reinforcing mesh by1902 Hilfiker Lane spiral binders.vary in spacing and gauges to meet projectEureka, CA 95503design specifications.Eureka Reinforced SoilWelded steel wire mesh, Galvanized orPrecast or cast-in-place concrete facingHilfiker Retaining Wallspanels, shotree,sculpted shotcrete,oNon-Galvanized.Mesh reinforcements1902 Hilfiker Lanevary in spacing and gauges to meet projectstacked stone.Eureka,CA95503design specifications.Steepened SlopeWelded steel wire mesh, Galvanized orWelded steel wire mesh, I to I slopeHilfiker Retaining WallsNon-Galvanized. Mesh reinforcementstypical. Hardware Cloth or Filter Fabric1902 Hilfiker Lanevary in spacing and gauges to meet projectdepending on project. (With geotextile orEureka, CA 95503design specifications.shotcrete, if desired)INTER-LOK0.63 or 0.75 in. reinforcing steel bars fittedPrecast concrete panel; cross-shaped 6 ftAtlantic Concrete Industrieswith 5 x 10 x 0.4 in. anchor plates andwide and 3 ft high, 8 and 10 in. thick.P.O. Box 129connected to a keyplate,and galvanizedTullytown, PA 19007after fabrication.ISOGRIDRectangular grid of W11 x W11Diamond shaped precast concrete units,5Neel Co.4 bars per grid.ft x 8 ff, 5.5 in, thick.6520Deepford StreetSpringfield, VA 22150T-Block Wall SystemRectangular 4 ft wide welded steel wireDry cast concrete block 8 in high x 16 inT&B Structural Systems LLCmesh of W7 to W20 steel bars.long x 12 in deep.6800 Manhattan BlvdSte 304Ft.Worth Texas 76120MESAHDPE GeogridMESA HP (high performance), DOTTensar International CorporationOR Standard units (8 in. high by 18 in.5883 Glenridge Drive, Suite 200long face, 10.8 in. nominal depth). (dryAtlanta, GA30328cast concrete)PyramidrMGalvanized welded wire ladders. SizeDry cast concrete units, 8 in, high, 16 in.The Reinforced Earth Companyvaries with design requirements.nominal length at face, 10 in. nominal8614 Westwood Center Drivedepth,Suite 1100Vienna, VA22182-2233OmegaGeostraps composed of high tenacityCruciform and square shaped precastThe Reinforced Earth Companypolyester with polyethylene sheathing.concrete 5 ft x 5 ft x 5.5 in. thick. Also8614 Westwood Center DriveReinforcement used in marine andrectangular shaped precast concrete 5 ft xSuite110010 ft x 5.5 in. thick. Variable heightcorrosive environments only.Vienna, VA 22182-2233panels used at top and bottom of wall.Geotre/MWelded steel wire mesh with geotextileGeostrapscomposedof hightenacityThe Reinforced Earth Companypolyester with polyethylene sheathing.backing.8614 Westwood Center Dr,Ste 1100Only used in temporary walls.Vienna,VA221821-IntroductionFHWA NHI-10-0241-8MSEWallsandRSS-VollNovember2009
System Name Reinforcement Detail Typical Face Detail1 Welded Wire Wall Welded steel wire mesh, Galvanized or Welded steel wire mesh, 2’ tall x 8’ wide Hilfiker Retaining Walls Non-Galvanized. Mesh reinforcements typical. Backing mat, Hardware Cloth or 1902 Hilfiker Lane vary in spacing and gauges to meet project Filter Fabric depending on project. (With Eureka, CA 95503 design specifications. geotextile or shotcrete, if desired). Reinforced Soil Embankment Welded steel wire mesh, Galvanized or Precast concrete unit 12.5 ft long, 24 in. Hilfiker Retaining Walls Non-Galvanized. Mesh reinforcements high. 1902 Hilfiker Lane vary in spacing and gauges to meet project Eureka, CA 95503 design specifications. ArtWeld Gabions Welded steel wire mesh, Galvanized or ArtWeld Gabion baskets of various sizes Hilfiker Retaining Walls Non-Galvanized. Mesh reinforcements and heights designed per project 1902 Hilfiker Lane vary in spacing and gauges to meet project requirements. Eureka, CA 95503 design specifications. Gabion Faced M.S.E. Welded steel wire mesh, Galvanized or ArtWeld Gabions of various sizes and Hilfiker Retaining Walls Non-Galvanized. Mesh reinforcements heights connected to reinforcing mesh by 1902 Hilfiker Lane vary in spacing and gauges to meet project spiral binders. Eureka, CA 95503 design specifications. Eureka Reinforced Soil Welded steel wire mesh, Galvanized or Precast or cast-in-place concrete facing Hilfiker Retaining Walls Non-Galvanized. Mesh reinforcements panels, shotcrete, sculpted shotcrete, or 1902 Hilfiker Lane vary in spacing and gauges to meet project stacked stone. Eureka, CA 95503 design specifications. Steepened Slope Welded steel wire mesh, Galvanized or Welded steel wire mesh, 1 to 1 slope Hilfiker Retaining Walls Non-Galvanized. Mesh reinforcements typical. Hardware Cloth or Filter Fabric 1902 Hilfiker Lane vary in spacing and gauges to meet project depending on project. (With geotextile or Eureka, CA 95503 design specifications. shotcrete, if desired). INTER-LOK 0.63 or 0.75 in. reinforcing steel bars fitted Precast concrete panel; cross-shaped 6 ft Atlantic Concrete Industries P.O. Box 129 Tullytown, PA 19007 with 5 x 10 x 0.4 in. anchor plates and connected to a keyplate, and galvanized after fabrication. wide and 3 ft high, 8 and 10 in. thick. ISOGRID Rectangular grid of W11 x W11 Diamond shaped precast concrete units, 5 Neel Co. 6520 Deepford Street Springfield, VA 22150 4 bars per grid. ft x 8 ft, 5.5 in. thick. T-Block Wall System Rectangular 4 ft wide welded steel wire Dry cast concrete block 8 in high x 16 in T&B Structural Systems LLC 6800 Manhattan Blvd Ste 304 Ft. Worth Texas 76120 mesh of W7 to W20 steel bars. long x 12 in deep. MESA Tensar International Corporation 5883 Glenridge Drive, Suite 200 Atlanta, GA 30328 HDPE Geogrid MESA HP (high performance), DOT3 OR Standard units (8 in. high by 18 in. long face, 10.8 in. nominal depth). (dry cast concrete) Pyramid™ The Reinforced Earth Company 8614 Westwood Center Drive Suite 1100 Vienna, VA 22182-2233 Galvanized welded wire ladders. Size varies with design requirements. Dry cast concrete units, 8 in. high, 16 in. nominal length at face, 10 in. nominal depth. Omega The Reinforced Earth Company 8614 Westwood Center Drive Suite 1100 Vienna, VA 22182-2233 Geostraps composed of high tenacity polyester with polyethylene sheathing. Reinforcement used in marine and corrosive environments only. Cruciform and square shaped precast concrete 5 ft x 5 ft x 5.5 in. thick. Also rectangular shaped precast concrete 5 ft x 10 ft x 5.5 in. thick. Variable height panels used at top and bottom of wall. GeotrelTM The Reinforced Earth Company 8614 Westwood Center Dr, Ste 1100 Vienna, VA 22182 Geostraps composed of high tenacity polyester with polyethylene sheathing. Only used in temporary walls. Welded steel wire mesh with geotextile backing. FHWA NHI-10-024 1 – Introduction MSE Walls and RSS – Vol I 1 – 8 November 2009
Tvpical Face DetailSystemNameReinforcement DetailTerratre/TMRibbed galvanized steel strips, 0.157 in.Welded steel wire mesh with geotextileThe Reinforced Earth Companythick, 2 in. wide. Or, galvanized steelbacking or stone fillat wall face.8614 Westwood Center Driveladder strips or mesh. Size varies withSuite 1100design requirements.Vienna, VA 22182-2233Maccaferri Terramesh SystemContinuous sheets of galvanized doubleRock flled gabion baskets laced toMaccaferri Gabions, Inc.twisted woven wire mesh with PVCreinforcement.43A Governor Lane Blvd.coating.Williamsport,MD21795Strengthened EarthRectangular grid,w7,w9.5 and W14,Precast concrete units, rectangularor wingGifford-Hill & Co.shaped, 6 ft x7ftx 5.5 in.transverse bars at 9 and 18 in.2515 McKinney Ave.Dallas, Texas 75201MSEPlusRectangular grid with W8 to W24Rectangular precast concrete panels 5 ftSSLlongitudinal bars and W8 to W20high, 5, 6, 10, and 12 ft wide, with a4740 Scotts Valley Drivetransverse. Mesh may have 2-6thickness of6or7inScotts Valley,CA 95066longitudinal bars spaced at 6 or 8 in.KeySystem-InextensibleGalvanized welded wire ladder mat ofKeySystem concrete facing unit is 8 inKeystone Retaining Wall SystemsW7.5toW17bars with crossbars at6-24highx 18 in, wide x 12 in. deep(dry cast4444 W.78 Streetin.concrete).Minneapolis, MN 55435KeySystem -ExtensibleMiragrid high-tenacity polyester geogridKeystone Compac concrete facing unitsKeystone Retaining Wall Systemssoil reinforcement by TenCate Mirafi,are 8 in. high x 18 in. wide x 12 in. deep4444 W.78 Streetpolymer coated.(dry cast concrete).Minneapolis, MN 55435Tricon SystemGalvanized welded-wire.Rectangular precast concrete panels withTricon Precast Ltd.a face area of 45 sq.ft.15055Henry RoadHouston, TX 77060Versa-Lok Retaining Wall SystemsPVC coated PET or HDPE geogrids.Versa-Lok concrete unit 6 in high x 16 in.6348 Highway 36 Blvd.long x 12 in. deep (dry cast concrete)Oakdale, MN 55128Anchor Wall SystemsPVC coated PET geogrid.Anchor Landmark concrete unit 15 in.5959 Baker Roadhigh x 8 in. long x 12 (small unit) or 12.5Minnetonka, MN55345(large unit) in. deep (dry cast concrete).EarthTrac"HARibbed galvanized steel strips, 0.188 in.Rectangular 5 ft x 10 ft precast concreteEarthTec Inc.thick by 2.36 in, wide.panels.413 Browning Ct.Purcellville, VA 20132EarthTracIM WireWelded wire basket 2.5 ft high by 10 ftRibbed steel strips, 0.188 in. thick by 2.36EarthTec Inc.wide.in. wide, galvanized for permanent walls.413 Browning Ct.Purellville, VA 20132EarthTracTM SyntheticPVC coated high tenacity polyesterPrecast concrete panels, rectangular or T-EarthTec Inc.shaped.geostraps.413 Browning Ct.Purcellville,VA 20132'Additional facingtypes are possible with most systems.TheeuseofgeotextilesinMSEwallsandRSSS started after the beneficial effect ofreinforcementwithgeotextileswasnoticedinhighwayembankmentsconstructedoverweaksubgrades.The first geotextile-reinforced wall was constructed in France in 1971, and thefirst structure of this type in the United States was constructed in 1974.Geogrids for soilFHWA NHI-10-0241-1Introduction1-9November2009MSEWallsandRSS-VolI
System Name Reinforcement Detail Typical Face Detail1 Terratrel™ The Reinforced Earth Company 8614 Westwood Center Drive Suite 1100 Vienna, VA 22182-2233 Ribbed galvanized steel strips, 0.157 in. thick, 2 in. wide. Or, galvanized steel ladder strips or mesh. Size varies with design requirements. Welded steel wire mesh with geotextile backing or stone fill at wall face. Maccaferri Terramesh System Maccaferri Gabions, Inc. 43A Governor Lane Blvd. Williamsport, MD 21795 Continuous sheets of galvanized double twisted woven wire mesh with PVC coating. Rock filled gabion baskets laced to reinforcement. Strengthened Earth Gifford-Hill & Co. 2515 McKinney Ave. Dallas, Texas 75201 Rectangular grid, W7, W9.5 and W14, transverse bars at 9 and 18 in. Precast concrete units, rectangular or wing shaped, 6 ft x 7 ft x 5.5 in. MSE Plus SSL 4740 Scotts Valley Drive Scotts Valley, CA 95066 Rectangular grid with W8 to W24 longitudinal bars and W8 to W20 transverse. Mesh may have 2 – 6 longitudinal bars spaced at 6 or 8 in. Rectangular precast concrete panels 5 ft high, 5, 6, 10, and 12 ft wide, with a thickness of 6 or 7 in. KeySystem – Inextensible Keystone Retaining Wall Systems 4444 W. 78th Street Minneapolis, MN 55435 Galvanized welded wire ladder mat of W7.5 to W17 bars with crossbars at 6 – 24 in. KeySystem concrete facing unit is 8 in high x 18 in. wide x 12 in. deep (dry cast concrete). KeySystem – Extensible Keystone Retaining Wall Systems 4444 W. 78th Street Minneapolis, MN 55435 Miragrid high-tenacity polyester geogrid soil reinforcement by TenCate Mirafi, polymer coated. Keystone Compac concrete facing units are 8 in. high x 18 in. wide x 12 in. deep (dry cast concrete). Tricon System Tricon Precast Ltd. 15055 Henry Road Houston, TX 77060 Galvanized welded-wire. Rectangular precast concrete panels with a face area of 45 sq. ft. Versa-Lok Retaining Wall Systems 6348 Highway 36 Blvd. Oakdale, MN 55128 PVC coated PET or HDPE geogrids. Versa-Lok concrete unit 6 in. high x 16 in. long x 12 in. deep (dry cast concrete) Anchor Wall Systems 5959 Baker Road Minnetonka, MN 55345 PVC coated PET geogrid. Anchor Landmark concrete unit 15 in. high x 8 in. long x 12 (small unit) or 12.5 (large unit) in. deep (dry cast concrete). EarthTracTM HA EarthTec Inc. 413 Browning Ct. Purcellville, VA 20132 Ribbed galvanized steel strips, 0.188 in. thick by 2.36 in. wide. Rectangular 5 ft x 10 ft precast concrete panels. EarthTracTM Wire EarthTec Inc. 413 Browning Ct. Purcellville, VA 20132 Ribbed steel strips, 0.188 in. thick by 2.36 in. wide; galvanized for permanent walls. Welded wire basket 2.5 ft high by 10 ft wide. EarthTracTM Synthetic EarthTec Inc. 413 Browning Ct. Purcellville, VA 20132 PVC coated high tenacity polyester geostraps. Precast concrete panels, rectangular or Tshaped. 1 Additional facing types are possible with most systems. The use of geotextiles in MSE walls and RSS started after the beneficial effect of reinforcement with geotextiles was noticed in highway embankments constructed over weak subgrades. The first geotextile-reinforced wall was constructed in France in 1971, and the first structure of this type in the United States was constructed in 1974. Geogrids for soil FHWA NHI-10-024 1 – Introduction MSE Walls and RSS – Vol I 1 – 9 November 2009
reinforcement were developed around 1980. The first use of geogrid in earth reinforcementwas in 1981. Extensive use of geogrid products in the United States started in about 1983,and they now comprise a growing portion of the market.Since the early 198Os, the use ofgeosynthetics in reinforced soil structures has increased significantlyThe first reported use of reinforced steepened slopes is believed to be the west embankmentfor the Great Wall of China.The introduction and economy of geosynthetic reinforcementshas made the use of steepened slopes economically attractive.A survey of usage in the mid1980s identified several hundred completed projects.At least an order of magnitude moreRss structures have been constructed since that study.The highest constructed Rssstructure in the U.S.to date is 242ft (74m) (see Chapter 8)A representative list of geosynthetic reinforcement manufacturers and suppliers is shown inTable 1-2Current Usage:It is believed that MSEWs have been constructed in every state in theUnited States.Major users include transportation agencies in Georgia, Florida, Texas,Pennsylvania, New York, and California, which rank among the largest road building states.It is estimated that more than 9,000,000 ft’ (850,000 m) of MSE retaining walls with precastfacing are constructed on average every year in the United States, which may represent morethan half of allretainingwall usagefor transportation applications.The majority of the MSEWs for permanent applications either constructed to date orpresently planned use a segmental precast concrete facing and galvanized steelreinforcements.The use of geotextile faced MSEWs in permanent construction has beenlimited to date. They are quite useful for temporary construction, where more extensive usehas been made.Recently,modular blockdry castfacing units have gained acceptance dueto their lowercostand nationwide availability.These small concrete units are generally mated with gridreinforcement, and the wall system is referred to as modular block wall (MBW).It isestimated that more than 3,000,000 ft? (280,000 m) of MBW walls have been constructedyearly in the United States when considering all types of transportation related applications.The current yearly usage for transportation-related applications is estimated at about 100projects peryear.The use of RsS structures has expanded dramatically in the last decade, and it is estimatedthat several hundred RsS structures have been constructed in the United States. Currently,FHWA NHI-10-0241- Introduction1-10MSEWallsandRSS-VolINovember2009
reinforcement were developed around 1980. The first use of geogrid in earth reinforcement was in 1981. Extensive use of geogrid products in the United States started in about 1983, and they now comprise a growing portion of the market. Since the early 1980s, the use of geosynthetics in reinforced soil structures has increased significantly. The first reported use of reinforced steepened slopes is believed to be the west embankment for the Great Wall of China. The introduction and economy of geosynthetic reinforcements has made the use of steepened slopes economically attractive. A survey of usage in the mid 1980s identified several hundred completed projects. At least an order of magnitude more RSS structures have been constructed since that study. The highest constructed RSS structure in the U.S. to date is 242 ft (74 m) (see Chapter 8). A representative list of geosynthetic reinforcement manufacturers and suppliers is shown in Table 1-2. Current Usage: It is believed that MSEWs have been constructed in every state in the United States. Major users include transportation agencies in Georgia, Florida, Texas, Pennsylvania, New York, and California, which rank among the largest road building states. It is estimated that more than 9,000,000 ft2 (850,000 m2 ) of MSE retaining walls with precast facing are constructed on average every year in the United States, which may represent more than half of all retaining wall usage for transportation applications. The majority of the MSEWs for permanent applications either constructed to date or presently planned use a segmental precast concrete facing and galvanized steel reinforcements. The use of geotextile faced MSEWs in permanent construction has been limited to date. They are quite useful for temporary construction, where more extensive use has been made. Recently, modular block dry cast facing units have gained acceptance due to their lower cost and nationwide availability. These small concrete units are generally mated with grid reinforcement, and the wall system is referred to as modular block wall (MBW). It is estimated that more than 3,000,000 ft2 (280,000 m2 ) of MBW walls have been constructed yearly in the United States when considering all types of transportation related applications. The current yearly usage for transportation-related applications is estimated at about 100 projects per year. The use of RSS structures has expanded dramatically in the last decade, and it is estimated that several hundred RSS structures have been constructed in the United States. Currently, FHWA NHI-10-024 1 – Introduction MSE Walls and RSS – Vol I 1 – 10 November 2009