47 EARTH RETAINING SYSTEMS
47-1 General
47-1.01 General
Section 47 includes specifications for constructing earth retaining systems.
47-1.02 Materials
Not Used
47-1.03 Construction
Not Used
47-1.04 Pa Yment
Not Used
47-2 Mechanically Stabilized Embankment
47-2.01 General
47-2.01A Summary
Section 47 -2 includes specifications for constructing mechanically stabilized embankments. Concrete panels must comply with section 51. Reinforcement must comply with section 52. Geosynthetic reinforcement must comply with section 96. Earthwork must comply wit h section 19.
47-2.01B Definitions
Reserved
47-2.01C Submittals
Submit results from the proposed button -head wire coupler test. Submit results from each production button -head wire coupler test.
47-2.01D Quality Assurance
47-2.01D(1) General
Coupler te st samples must comply with the minimum tensile specifications for plain wire in ASTM A1064A/1064M. Total wire slip must be at most 3/16 inch when tested as specified for tension testing of round wire test samples under ASTM A370. If any test samples fail, revise the connection and retest. Do not start face panel installation until tension and slip test results are accepted. Perform tension and slip tests on the proposed button -head wire soil reinforcement and coupler connection. Test 6 connection test samp les. Test samples must consist of two 24 -inches long button - head wires connected by a swaged coupler. Testing must be performed by an authorized laboratory.
47-2.01D(2) Quality Control
Perform tension and slip testing on production button -head wire and co upler connections during wall construction. Test 4 connection test samples for each lot of 500 mat wire connections installed. If 2 or more test samples fail, the entire represented lot is rejected. If 1 test sample fails to comply with specified criteria, test an additional 4 test samples. If any of these additional samples fail, the entire represented lot is rejected.
47-2.02 Material S
47-2.02A General
Concrete leveling pads must be constructed with minor concrete. SECTION 47 EARTH RETAINING SYSTEMS Soil reinforcement, connecting element s, and other steel components in contact with the earth must be galvanized under section 75 -1.02B. Threaded ends of inspection wires for metallic soil reinforcement may be formed before or after galvanizing. Coat the final 4 inches of the wire with 2 appli cations of organic zinc -rich primer. Encase the threaded end with a waterproof vinyl enclosure secured with a nylon tie. If the threaded end is galvanized after threading, clean the threads before painting. Corrugated steel pipe must comply with section 66 . Perforated pipe underdrains and underdrain outlets and risers must comply with section 68 -2. Perforated pipe must be steel unless perforated plastic pipe is shown. Rock for rock slope protection at drain pipe outlets must be small -rock slope protection a nd must comply with the gradation specified for 7 -inch-thick layer in section 72 -4.02. Filter fabric must be Class A. Adhesive for bonding filter fabric to concrete panels must be commercial grade. Resin bonded cork for horizontal joints must comply with ASTM D1752, Type II, with a compressive load of at least 100 psi. Pipe pins must comply with ASTM A53/A53M except the zinc coating of actual surface must average at least 2.0 oz/sq ft and no individual specimen may be less than 1.8 oz/sq ft.
47-2.02B Face Panels
In freeze -thaw areas concrete panels must comply with section 90 -1.02I and must contain at least 675 pounds of cementitious material per cubic yard. If architectural treatment is not required, finish exposed surfaces of concrete members as spe cified for Class 1 surface finish under section 51 -1.03F(3).
47-2.02C Structure Backfill
Structure backfill for mechanically stabilized embankment must:
1.Be free of organic material and substantially free of shale and other soft material of poor durabil ity
2.Not contain slag aggregate or recycled materials such as: 2.1. Glass 2.2. Shredded tires 2.3. Portland cement concrete rubble including asphaltic dust, sand, rock, grindings, slabs, and boulders 2.4. Asphaltic concrete rubble including asphaltic dus t, sand, rock, grindings, slabs, and boulders 2.5. Other unsuitable material as determined by the Engineer For an embankment with metallic soil reinforcement, structure backfill must comply with the requirements shown in the following tables: Gradation Re quirements Sieve size Test method Requirement (percent passing) 6" California Test 202 100 3" California Test 202 78–100 No. 30 California Test 202 0–60 No. 200 California Test 202 0–15 SECTION 47 EARTH RETAINING SYSTEMS Quality Characteristic Requirements Quality characteristic Test method Requirement Sand equivalenta (min) California Test 217 12 Plasticity indexa (max) California Test 204 6 Minimum resistivity (ohm -cm) California Test 643 2000 Chlorides (ppm) California Test 422 < 250 Sulfates (ppm) California Test 417 < 500 pH California Test 643 5.5–10.0 aDoes not apply if 12 percent or less passes the no. 200 sieve and 50 percent or less passes the no. 4 sieve. For an embankment with geosynthetic soil reinforcement, structure backfill must comply with the requirements shown in the following tables: Gradation Requirements Sieve size Test method Requirement (percent passing) 2" California Test 202 100 No. 4 California Test 202 50–80 No. 40 California Test 202 0–30 No. 200 California Test 202 0–15 Quality Characteristic Requirements Quality characteristic Test method Requirement Sand equivalenta (min) California Test 217 12 Plasticity indexa (max) California Test 204 6 Durability Index (min) California Test 229 35 pH California Test 643 4.5–9.0 aDoes not apply if 12 percent or less passes the no. 200 sieve and 50 percent or less passes the no. 4 sieve.
47-2.02D Permeable Material
Permeable material must be Class 1, Type B, complying with section 68-2.02F. Permeable material for an emb ankment with metallic soil reinforcement must comply with the requirements shown in the following table: Quality Characteristic Requirements Quality characteristic Test method Requirement Minimum resistivity (ohm -cm) California Test 643 2,000 Chlorides (max, ppm) California Test 422 250 Sulfates (max, ppm) California Test 417 500 pH California Test 643 5.5–10.0 Permeable material for an embankment with geosynthetic soil reinforcement must comply with the requirements shown in the following table: Quality Characteristic Requirements Quality characteristic Test method Requirement pH California Test 643 4.5–9.0
47-2.02E Soil Reinforcement
Steel wire must comply with the specifications for plain wire reinforcement in ASTM A1064/A1064M. Welded wire reinforcement must comply with the specifications for plain wire welded wire reinforcement in ASTM A1064/1064M. SECTION 47 EARTH RETAINING SYSTEMS For button -headed wires:
1.Buttons must be cold formed symmet rically about the axes of the wires
2.Buttons must develop the minimum guaranteed ultimate tensile strength of the wire
3.Do not use a cold -forming process that causes indentations in the wire
4.Button heads must not contain wide open splits, more than 2 splits per head, or splits nonparallel to the axis of the wire Steel wire reinforcement hooks and bends must comply with the Building Code Requirements for Structural Concrete published by ACI. Couplers at wire reinforcement connections must be seamless steel sleeves applied over the button -head wires. Couplers must develop the wire minimum tensile strength with a total slip of at most 3/16 inch. Splice welded wire reinforcement along its length with mechanical couplers that develop the minimum tensile s trength of the wire. Identification, storage, and handling of geosynthetic reinforcement must comply with ASTM D4873 and any alternative system details. Protect the geosynthetic reinforcement from chemicals, flames, welding sparks, and temperatures less th an 20 degrees F or greater than 140 degrees F. Do not allow foreign materials to come into contact with or become affixed to the geosynthetic reinforcement.
47-2.03 Construction
47-2.03A General
Water for earthwork or for dust control within 500 feet of structures with metallic soil reinforcement must comply with the specifications for water in reinforced concrete in section 90 -1.02D. Protect the unthreaded portion of the galvanized inspection wire from damage.
47-2.03B Earthwork
47-2.03B(1) General
Grade the foundation level for a width equal to the length of soil reinforcement elements plus 1 foot or as shown. Compact foundation material to a relative compaction of at least 95 percent. Start wall construction activities after the Engineer ac cepts the compacted foundation area. If ordered, remove unsuitable material. This work is change order work. Place structure backfill simultaneously with erection of facing panels. Place and compact material without distorting soil reinforcement or displac ing facing panels. Place structure backfill at the front of the wall before backfilling more than 15 feet above the bottom of the lowermost face element. If a mechanically stabilized embankment with soil reinforcement is to be constructed on an embankment, compact embankment material to a relative compaction of at least 95 percent within the limits established by inclined planes sloping 1.5:1 (horizontal:vertical) from lines 1 foot outside the bottom limits of the mechanically stabilized embankment, includi ng any permeable material. Start placing and compacting structure backfill 1 foot from the back face of wall panels and progress toward the free end of the soil reinforcement. Operate compaction equipment parallel to the wall facing. Place and compact the remaining width of backfill behind wall panels after covering the soil reinforcement to a depth of 6 inches. Do not use sheepsfoot or grid -type rollers within the limits of soil reinforcement. Use hand -held or hand - guided compacting equipment within 3 feet of facing panels. Place structure backfill at each level of soil reinforcement to a plane 2 inches above the elevation of the soil reinforcement connection, starting 3 feet from the back of the face panel and extending for at least the remaining length of soil reinforcement. Complete this grading before placing the next layer of soil reinforcement. Place permeable material and filter fabric when placing structure backfill. Place permeable material in layers less than 2 feet thick. Compaction of permeable m aterial for the drainage system outside the limits of soil reinforcement is not required. Do not operate equipment directly on the permeable material or filter SECTION 47 EARTH RETAINING SYSTEMS fabric. If a sloped layer of permeable material is placed to facilitate the work or to satisfy s afety considerations, (1) the vertical limits of the permeable material must remain unchanged and (2) the thickness of the layer of permeable material is measured normal to the slope. Grade backfill to drain away from the wall face at the end of each work shift. Use berms or ditches to direct runoff away from the wall site. Do not allow surface runoff from adjacent areas to enter the wall site.
47-2.03B(2) Soil Reinforcement
Tension soil reinforcement in the direction perpendicular to the wall face. Remove slack in the connection and the soil reinforcement. Secure soil reinforcement in place before and during compaction. Swage wire reinforcement couplers with a hydraulic press. Cover soil reinforcement with structure backfill during the same work shift that it is placed. Do not operate construction equipment directly on soil reinforcement. Maintain a layer of structure backfill at least 6 inches thick between soil reinforcement and any construction equipment. Place geosynthetic soil reinforcement in full -length sections. Place structure backfill over geosynthetic soil reinforcement in lifts of at most 6 inches if using hand - operated compaction equipment and 8 inches if using heavy compaction equipment.
47-2.03B(3) Face Panels
Vertical and horizontal panel al ignment offset must not exceed 3/4 inch when measured along a 10 -foot straightedge. The offset in any panel joint must not exceed 3/4 inch. After placing backfill 2 feet above inspection elements, dry pack voids in face panels with mortar under section 51 -1.03E(2). Mortar must comply with section 51 -1.02F except the proportion of cementitious material to sand must be such that the mortar achieves a 28 day compressive strength of 1,000 to 1,500 psi.
47-2.03C Filter Fabric
Immediately before placing filter f abric, the subgrade to receive filter fabric must be free of loose or extraneous material and sharp objects that may damage the filter fabric. Concrete panel surfaces to receive filter fabric must be dry and thoroughly cleaned. Handle and place filter fabr ic under the manufacturer's instructions. Stretch, align, and place fabric without wrinkling. Adjacent borders of filter fabric must be stitched or overlapped. Overlap rolls 12 to 18 inches. Place the preceding roll over the following roll in the direction the material is being spread. Stitch fabric using yarn of a contrasting color. Yarn size and composition must comply with the filter fabric manufacturer's instructions. Use 5 to 7 stitches per inch of seam. Repair damaged filter fabric by placing a piece of filter fabric large enough to cover the damaged area and provide at least a 12 -inch overlap. Do not operate equipment, including vehicles, directly on filter fabric. Maintain at least 6 inches of permeable material between filter fabric and equipment du ring spreading of permeable material. Where structure backfill is to be placed on filter fabric, maintain at least 18 inches of structure backfill material between filter fabric and equipment during placement.
47-2.03D Leveling Pads
Place concrete for leveling pads at least 24 hours before erecting face panels.
47-2.04 Payment
The vertical height of each section is the difference in elevation on the outer face from the bottom of the lowermost face element to the top of wall profile. SECTION 47 EARTH RETAINING SYSTEMS
47-3 47-4 Reserved
47-5 Type 6 Retaining Walls
47-5.01 General
Section 47 -5 includes specifications for constructing Type 6 retaining walls. Reinforced concrete footings and stems must comply with section 51. Reinforcement must comply with s ection 52. CMU stems must comply with section 58 -2.
47-5.02 Materials
Hollow CMUs must comply with the specifications for normal weight CMUs in ASTM C90 and must be of uniform color and size. Caulking for sealing expansion joints must be a non -sag polysul fide or polyurethane type complying with ASTM C920. Grout must comply with section 58 -2.02D and contain at least 590 lb/cu yd of cementitious material.
47-5.03 Construction
You may construct wall stems of reinforced concrete or reinforced CMUs. Use only 1 stem type for each wall. CMU construction must be true and plumb. Provide recesses in the units for horizontal reinforcement. Provide cleanout openings at the bottom of cells where the wall height is over 4 feet. Seal cleanouts after inspection and before filling cells with grout. Lay units with full mortar coverage of the face in both vertical and horizontal joints except at weep holes. Shove vertical joints tight. Exposed joints must be concave and tooled smooth. Fill cells in hollow unit masonry with gr out. Consolidate grout while pouring by puddling or vibrating. Place the top lift of grout approximately 1 inch below the top of units. Place a mortar cap above the top lift. Do not place backfill against the back of Type 6 retaining walls until grout comp ressive strength has reached 1,500 psi or until the grout has cured for 28 days.
47-5.04 Payment
The payment quantity for retaining wall stem (Type 6) is the area determined from the dimensions shown. The height is the difference in elevation from the top of the footing to the top of the wall.
47-6 Alternative Earth Retaining Systems
47-6.01 General
47-6.01A Summary
Section 47 -6 includes specifications for constructing alternative earth retaining systems. You may use an alternative earth retaining system when specified in the special provisions. Use only one type of system at any one location. The alternative earth reta ining system must comply with the specifications for the type of wall being constructed.
47-6.01B Definitions
Reserved
47-6.01C Submittals
47-6.01C(1) General
For as -built drawings common to more than one structure, submit the as -built drawings for each structure. SECTION 47 EARTH RETAINING SYSTEMS
47-6.01C(2) Shop Drawings
Submit shop drawings and calculations for the alternative system electronically to sc.office.associates@dot.ca.gov . Include the f ollowing:
1.All information required for construction of the system at each location
2.Existing ground line at the wall face
3.Design parameters, material notes, and wall construction procedures Verify existing ground elevations before submitting drawi ngs. Shop drawings and calculations must be sealed and signed by an engineer who is registered as a civil engineer in the State . Allow 30 days for the Department's review.
47-6.01C(3) Certificates
Submit certificates of compliance for the alternative system stating the supplied materials comply with the authorization criteria for the system on the Authorized Material List for alternative earth retaining systems.
47-6.01D Quality Assurance
A qualified representative of the alternative syste m manufacturer must be present during erection and backfill of the first 10 vertical feet of the entire length of the wall. The representative must be available during the remaining installation. The representative must not be your employee.
47-6.02 Mater Ials
The alternative systems specified are taken from the Authorized Material List. Only systems having characteristics suitable for this project are specified. Some systems may be proprietary. Alternative systems are selected based on data previously furn ished by suppliers or manufacturers of each system.
47-6.03 Construction
The structure must comply with the system details authorized on the Authorized Material List. Check vertical and horizontal alignment at each course during erection. Include a drainage system where shown. Where shown, construct the alternative system to accommodate (1) wall -mounted lighting and drainpipes and (2) panels for future drainage inlets. The top of wall profile must conform to the profile shown. The bottom of wall elev ations must be at or below the elevations shown. Use a minimum height and length of wall adequate for the loading and site conditions described. The length of soil reinforcement for any system must not be less than that shown. The coping lip or barrier sla b lip must cover the top of face panels at least 7 inches. Place the top level of soil reinforcement:
1.Parallel to the top of the concrete panel
2.At least 3 inches below the bottom of either the barrier slab lip or the concrete gutter behind the coping
3.At least 5 inches below the top edge of the concrete panel
47-6.04 Payment
Not Used
Source: California Standard Specifications, 2024 Edition. Pages 687–694 of 1,372.