Whether for transportation infrastructure, commercial, or residential projects, retaining walls offer an engineered and aesthetically pleasing solution for maximizing use of right-of-ways and building sites while providing erosion control and slope stability. In response to a request from CE News, companies provided the following information about their products. Company web addresses are provided for immediate access to additional information.
The Association for Metallically Stabilized Earth (AMSE) (www.amsewalls.org) represents suppliers of mechanically stabilized earth (MSE) structures using steel reinforcements. The association’s executive director, Robert A. Gladstone, P.E., a 35-year industry professional, can provide unbiased technical advice to engineers, architects, owners, and contractors who are planning, designing, or building MSE structures. Gladstone is also an instructor for the National Highway Institute’s inspector certification course, Inspection of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes (search for NHI 132080). AMSE members use steel strip, bar mat, or welded wire mesh reinforcements with precast concrete or wire facing to offer a variety of structural and architectural characteristics for retaining walls, bridge abutments, and similar load-bearing or earth-supporting structures.
According to Carthage Mills (www.carthagemills.com), its GX Geogrid features advanced weaving techniques and coating that help it achieve efficient, long-term design strengths and optimal segmental retaining wall (SRW) block connection values with nearly every major block system. Detailed information including product data, SRW connection data for each block/geogrid combination, installation guidelines, creep and creep rupture behavior, 10,000-hour creep results, and installation damage is accessible on the Carthage Mills GX website. Standard roll sizes are 6 feet x 300 feet and 4 feet x 45 feet. Wide-width material is available on request.
CMI Sheetpiling (www.cmisheetpiling.com) introduced two industrial-grade synthetic sheet piling options. According to the company, ShoreGuard GG-75 and GG-95 profiles are the largest fiber reinforced polymer composite sheet piling products in the world. Engineered to replace AZ-13 and PZ-22 steel sheet piling, the paired coverage of these two products is as wide as 60 inches. The new ShoreGuard profiles allow for retaining wall heights and coverage never before possible in synthetic sheet piling, the company says. The stiffness of the sheets also makes them an excellent alternative for cutoff wall, dike core, and dike extensions.
EarthTec (www.earthteccorp.com), a subsidiary of GeoStructures, designs and supplies a range of steel- and geosynthetic-based MSE structures, primarily for use in transportation infrastructure and commercial development projects. Its 5-foot x 10-foot precast concrete panel MSE system features ribbed steel strips that can be positioned to avoid obstructions such as drainage structures and bridge-support piles. EarthTec says it uses the widest and thickest galvanized, ribbed-steel strip in the industry, so it can reinforce the earth with fewer strips and allow for larger spans between strips to accommodate obstructions. In addition, since the strips are wider at the point where they are bolted to the precast panels, tensile capacity is maximized, and corrosion is minimized at the most critical location of the bolt hole.
Hilfiker Retaining Walls (www.hilfiker.com), a fourth-generation family business in operation since 1902, produces a full line of retaining wall systems, including welded wire walls, ArtWeld gabions, Trinity walls, gabion-faced MSE walls, welded wire steepened slope, reinforced soil embankment, Eureka reinforced soil, and Spiralnail. These products have been used in projects across the globe, ranging from state and federal department of transportation applications to major international mining sites. Hilfiker Retaining Walls provides on-site technical assistance to aid in wall start-up.
JET Filter’s (www.jetfiltersystem.com) flush-mount system is installed and maintained from the waterside of a new or existing seawall or retaining wall to relieve hydrostatic pressure on almost any wall design. Failure to provide proper weep-hole relief can result in water being trapped behind walls, causing erosion, pressure, and wall failure. The materials used in manufacturing the Jet Filter are UV protected, durable, and consistent with the life of the seawall or bulkhead.
Keystone Retaining Wall Systems, Inc.’s (www.keystonewalls.com) new Keystone 133Elite with the Hewnstone face combines great looks with an increased efficiency for large wall applications, according to the company. Its 8-inch x 24-inch face dimension creates a larger-scale look, aesthetically matching the larger wall look and feel, while reducing the number of units required to complete a job. In addition to conventional textures, Keystone’s StoneArt embossing technology can produce Keystone 133Elite units with specially designed natural textures in combination with the wide variety of colors available in most Keystone products. A mid-range weight allows installation by one person without special equipment.
Millenia Wall Solutions (www.milleniawalls.com) says its 100-percent recycled, polymer segmental retaining walls offer refined aesthetics, outstanding durability, labor-saving installation efficiency, and a lower environmental impact than traditional wall products. Millenia’s patented Structural Cell Technology replaces conventional retaining wall blocks with lightweight units consisting of a confinement cell secured to a rigid frame. The units weigh only 5 pounds per square foot. Unit-to-unit connection forms solid integral walls with consistent spacing and straight lines. The structural cross ribbing of the frames adds strength and rigidity, and beveled edges make it easier for installers to form smoothly curved walls. Once the units are set in place and secured, weight is achieved by adding crushed stone as fill. The units can also be secured to soil-reinforcing geogrids.
The National Concrete Masonry Association’s (www.ncma.org) SRWall v4.0 segmental retaining wall software includes features such as internal compound stability analysis, rectangular distribution update for seismic analysis, addition of vertical components, analysis of real geometry in broken back slopes, and influence of offset surcharges. According to the NCMA, SRWall v4.0 allows users to optimize designs and understand the behavior of wall components and possible failure conditions. The software, currently being tested, will be officially released in early 2009.
All Redi-Rock (www.redi-rock.com) products capture the essence of natural rock. Redi-Rock has developed its product line with attention to natural hardscapes and has, thus, developed a system that it says looks so natural that many mistake it for quarried stone. Redi-Rock’s retaining walls use blocks weighing more than 1 ton each. The massive scale of the system allows walls to be built much higher than other wall systems without using geogrid or tie-backs. Also, taller reinforced retaining walls can be designed with the company’s geo-connector.
RisiStone Systems’ (www.risistone.com) SienaStone combines the stability of large modular units with a popular natural rock-like appearance. Steps, curves, corners, and angles can be constructed with SienaStone and erected with light construction equipment. Under ideal conditions, SienaStone retaining walls can be built to a maximum height of 6 feet in excellent soil conditions with no loading, or higher with the use of the 37-inch units where available. The use of geogrid soil reinforcing techniques allow SienaStone retaining walls to be built to substantially greater heights with proper engineering design. The SienaStone segmental retaining wall system comprises 20-inch-deep, 7.25-inch-high, and 48-inch-wide standard units, coping units, octagon units, and corner units. Where available, 36-inch-deep standard units can increase the allowable maximum height of gravity walls.
Stone Strong Systems (www.stonestrong.com) is the largest fully engineered precast retaining wall block available on the market today. Based on a main block with a 24-square-foot face weighing 6,000 pounds, the patented void and lifting/alignment loops allow for an internal drainage system within the wall and help align the blocks during installation. The size and mass of the blocks allows for faster installations and taller gravity walls. Through development of a mass extender block or cast-in-place tail extensions, Stone Strong gravity walls have been installed to heights of 28 feet without geogrid reinforcement or other mechanical tiebacks.
The Sleeve-It System is a recent addition to Strata Systems’ (www.geogrid.com) full line of polymeric geogrid products. Sleeve-It is a foundation system that uses cantilever technology for anchoring perimeter fences and guards to mortarless block retaining walls. According to the company, Sleeve-It adds as much as 3 feet of buildable real estate along the entire length of a segmental retaining wall when compared with a retrofitted fence. The patent-pending Sleeve-it System is an extended family of products that includes steel-reinforced fence post integration systems for numerous commercial, residential and site amenity applications.
T&B Structural Systems (www.tbssus.com) provides fast, flexible, engineered embankment retention with MSE retaining walls in a variety of facing and soil reinforcing options. Its permanent or temporary welded wire wall systems consist of wire mesh facing, soil reinforcement, and compacted indigenous fill. The wire wall face can be left exposed, be vegetated, or designed and constructed with hardware that allows attachment of a variety of fascia options. These options include stone, masonry, shotcrete, or concrete panels (precast or cast-in-place) in many architectural treatments. The panel system is designed with unobstructed vertical joints, which allow for greater differential settlement of the MSE mass compared with systems that incorporate an interlocking joint.
The Reinforced Earth Company (www.reinforcedearth.com) says that since 1968, more than 150 million square feet of Reinforced Earth has been erected. According to the company, using pre-manufactured wall components, a crew of four and an equipment operator can complete 750 to 1,000 square feet of wall per shift, including backfill placement and compaction. Galvanized steel reinforcing strips are placed and bolted to the face panels. A variety of architectural finishes for the face panels are available to enhance the beauty of completed structures. Custom form liners are also available.
Truline (www.truline.us) offers a hybrid, cast-in-place wall system that combines the strength of concrete with the benefits of vinyl. Concrete can be poured into the cells to create a wall with additional strength and the weather-ability of vinyl, or it can be filled with gravel or sand, depending on the engineering specifications desired. According to the company, the system minimizes the need for barges, cranes, and other heavy equipment for installation; eliminates corrosion or discoloring; eliminates fracturing or soil erosion through the joints; reduces cure time; helps attain taller exposures; and minimizes the need for walers. The walls contain more than 94 percent recycled materials.
VERSA-LOK’s (www.versa-lok.com) new VERSA-Green Plantable Retaining Wall combines the durability and strength of a VERSA-LOK segmental retaining wall with the beauty of a hanging garden. Plantings in each wall unit grow to conceal the courses above or hang down to cover the wall below. VERSA-Green is a modified version of VERSA-LOK’s Square Foot segmental retaining wall system. Each VERSA-Green concrete unit weighs 70 pounds and covers nearly 1 square foot of wall face. Inside each unit is a 6-inch-deep cavity for planting and a 3/4-inch groove across the top to accommodate drip irrigation tubing that runs across each course parallel to the wall face.