548-1 Description.
Construct permanent and temporary retaining wall systems in accordance with this Section and in conformance with the lines, grades, design, and dimensions shown in the Contract or established by the Engineer. Sheet pile walls and cast -in-place walls are not included in this Section. Construct all walls of a specific type ( mechanically stabilized earth (MSE), counterfort, etc.), using the same wall system and supplier. If different t ypes of wall systems must be used in such a manner that causes one wall to interact with or influence another wall, coordinate the detailing of these areas of interaction/influence with the assistance of the Contractor’s Engineer of Record. Obtain each reinforced concrete precast concrete retaining wall system from a plant that is currently on the Department’s Production Facility Listing. Producers seeking inclusion on the list shall meet the requirements of Section 105. Ensure that each wall system compo nent is marked in accordance with 548 -5.3. Ensure that each shipment of products to the job site includes a signed or stamped delivery ticket in accordance with the Materials Manual, Section 8.2 Volume II, and the required written certification statement for each product shipped. Submit these tickets and certifications to the Engineer. When shown in the Plans or approved by the Engineer, a segmental block MSE retaining wall (SBW) system may be provided as a substitute for a reinforced concrete panel MSE w all system. All SBW systems must comprise:
1.Unreinforced dry -cast masonry facing blocks in a running bond pattern meeting the requirements of 548 -5.
2.Structural backfill reinforcement:
a.Type R -3 geosynthetic backfill reinforcement placed in sh eets full length without splices normal to the facing blocks and laterally without horizontal gaps, and with a vertical spacing of not more than every other course of blocks or 30 inches, whichever is less.
b.Metallic reinforcement placed full length w ithout splices normal to the facing blocks and spaced laterally and vertically not more than every other block or 30 inches, whichever is less, with a positive mechanical or shear connection to the facing blocks.
3.A mechanical shear connection to lock adjacent blocks together horizontally or vertically.
548-2 Materials.
Provide a wall system listed on the Department’s Approved Product List (APL) based on the wall type shown in the Plans. Purchase components, soil reinforcement, attachment devices, joint filler, filter fabric, and all necessary incidentals for each wall from the same wall supplier.
548-2.1 Concrete: Ensure that concrete utilized for all wall components is consistent
with the concrete class, environmental classification and admixture requirements for durability as stated in the Contract Documents . Produce and supply concrete for all reinforced concrete wall components meeting the requirements of Section 346. Produce and supply concrete for the leveling pad meeting the requirements of Section 347. Use Department approved mix designs. FY 2023-24 Return to Table of Contents
548-2.2 Reinf orcing Steel: Meet the requirements of Section 931 for steel reinforcing
and Section 932 for FRP reinforcing, as identified in the Contract Documents and APL drawings.
548-2.3 Backfill Reinforcement: For walls utilizing backfill reinforcement, use
reinforcement consisting of steel wire mesh, metal strips or structural geosynthetics as required for the wall system chosen. Use backfill reinforcement of the same length from top to bottom of wall at any section. For tiered walls, use backfill reinforcement of the same length within the height of each tier at any section. Use plain steel wire mesh and embedded loops shop fabricated from cold drawn steel wire and weld into the finished mesh fabric meeting the requirements of ASTM A1064. Use longitudinal and tra nsverse wires of equal and constant diameter within a given piece of mesh reinforcement. Use steel strips hot rolled from bars to the required shape and dimensions with physical and mechanical properties meeting ASTM A572 Grade 65 or as shown in the Contra ct. Use shop-fabricated hot rolled steel tie straps meeting the minimum requirements of ASTM A1011/A1011 M, Grade 50, or as shown in the Contract. Ensure that steel reinforcing strips, tie strips, reinforcing mesh and connectors used in permanent walls a re galvanized in accordance with ASTM A123 or ASTM A153, as applicable. For typical applications, punch or drill holes in metal items before galvanizing. Field drilled holes for bin walls are permitted. Repair field drilled holes; field cut ends and other damage to galvanized surfaces in accordance with Section 562. Use Type R-3 structural geosynthetics made of polypropylene, select high density polyethylene or high -tenacity polyester fibers having cross -sections sufficient to permit significant mechanica l interlock with the backfill. Use geosynthetics having a high tensile modulus in relation to the backfill. Use geosynthetics having high resistance to deformation under sustained long term design load while in service and resistant to ultraviolet degradat ion, to damage under normal construction practices and to all forms of biological or chemical degradation normally encountered in the material being reinforced. Do not use uncoated polyester (PET) reinforcements or reinforcements weakened or damaged by hig h pH environments within any portion of the flowable fill , or within coarse aggregate backfill below the design high water elevation (DHW) shown in the Plans . Store the geosynthetics in conditions above 20ºF and not greater than 140ºF. Prevent mud, wet cement, epoxy, and like materials from coming into contact with and affixing to the geosynthetic material. Rolled geosynthetic may be laid flat or stood on end fo r storage. Cover the geosynthetic and protect from sunlight prior to placement in the wall system. Carefully inspect all reinforcement, steel and geosynthetics to ensure they are the proper size and free from defects that may impair their strength and du rability.
548-2.4 Attachment Devices: Use backfill reinforcement attachment devices as required
by the wall system chosen.
548-2.5 Joint Materials and Filter Fabrics :
548-2.5 1 Horizontal Joint Pads: Use elastomeric or polymeric pads in all
horizontal joints between precast components as recommended by the wall manufacturer. Ensure that the pads are of sufficient size and hardness to limit vertical stresses on the pad and concrete surface and to prevent concrete to concrete contact at the joints.
548-2.5 2 Joint Covers for Non-SBW Walls : For walls supporting bridge
abutments on spread footings, cover joints and other wall openings within a horizontal distance equal to the larger of:
1.the length of the reinforcement under the footing plus 25 feet, or FY 2023-24 Return to Table of Contents
2.twice the maximum height of the footing above the leveling pad, measured from the nearest edge of the footing, surrounding the reinforced backfill for the abutment with Type D-2 geotextile fabric meeting the requirements of Section 985. Cover all joints and wall openings in portions of the wall backfilled with coarse aggregate with Type D-2 geotextile fabric meeting the requirements of Section 985. Cover all other joints and wall openings with Type D-2 or D-3 geotextile fa bric with a maximum apparent opening size ( AOS) equal to US Sieve No. 70 meeting the requirements of Section 985. Apply an adhesive approved by the Engineer to the back of the precast component for attachment of the fabric material.
548-2.5 3 Alignment P ins: Ensure that pins used to align the precast components
during construction are of the size, shape and material required for the wall system chosen.
548-2.5 4 Separation Geotextile: Provide a Type D-2, D-3, or D-5 separation
geotextile meeting the req uirements of Section 985 between the coarse aggregate and the select backfill/embankment at the bottom, top and sides of the coarse aggregate.
548-2.6 Backfill Material:
548-2.6 1 General: Provide compacted select backfill or coarse aggregate backfill
within the retaining wall volume as shown in the Plans. For permanent walls, p rovide coarse aggregate backfill in lieu of compacted select backfill to an elevation at least one foot above the DHW shown in the Plans when the DHW is above the lowest adjacent ground surface. Provide flowable fill within the retaining wall volume in lieu of compacted select backfill or coarse aggregate backfill only when the option for flowable fill is shown in the Plans. The retaining wall volume is defined to extend from the top of the leveling pad or footing, or bottom of walls which do not have footi ng or leveling pads, to the finish grade line and from the face of the wall to a vertical plane passing through the end of the extreme wall component (straps, counterforts, etc.) plus one foot.
548-2.6 2 Compacted Select Backfill: Meet the requirements o f Sections 105
and 120 except as noted within this Section. Have the backfill material tested for every soil type for pH, resistivity, sulfate and chloride content by a Department approved independent testing laboratory prior to placement. Submit a certifi cation, signed and sealed by a Professional Engineer registered in the State of Florida, that the results have met the requirements of this Section. The pH, as determined by FM 5-550, shall not be lower than 5.0 and not higher than 9.0 when metallic ele ments or pipes are placed within the backfill . Sources of select backfill material having a pH between 4.5 and 5.0 for walls utilizing metallic reinforcement and between 3.0 and 5.0 for walls utilizing geosynthetic , may be used provided the interior face of the MSE wall panels have three inches of concrete cover over the reinforcement and the concrete used in the panels contains the following ingredients and proportions:
1.The quantity of cement replaced with Type F fly ash is 10% to 20% by weight.
2.The quantity of cement replaced with slag is 50% to 60% by weight.
3.Portland cement is 30% by weight of total cementitious material.
4.The total weight of the Type F fly ash and slag does not exceed 70% of total cementitious material. FY 2023-24 Return to Table of Contents In lieu of the mix design described above, a mix design with a highly reactive pozzolan meeting the requirements of 346 -2.3 can be substituted. Examples of mix designs meeting this re quirement are :
1.8% silica fume plus 20% fly ash
2.10% metakaolin pl us 20% fly ash. Provide proper curing for these materials to prevent surface cracking. Do not place metallic pipe in backfill materials having a pH less than 5.0. In addition, for permanent walls utilizing metallic soil reinforcement, use backfill that meets the following electro -chemical test criteria for determining corrosiveness: Table 548-1 Electro-Chemical Test Criteria Criteria Test Method Resistivity: > 3000 ohm -·cm FM 5-551 Soluble sulfate content: < 200 PPM FM 5-553 Soluble chloride content < 100 PPM FM 5-552 For constructing the retaining wall volume, do not use backfill material containing more than 2.0% by weight of organic material, as determined by FM 1-T267 and by averaging the test results for three randomly selected samples from each stratum or stockpile of a particular material. If an individual test value of the three samples exceeds 3%, the stratum or stockpile will not be suitable for constructing the retaining wall volume. Ensure that the material is non -plastic as determined by AASHTO T 90 and the liquid limit as determined by AASHTO T 89 is less than 15. For walls using soil reinforcement, use backfil l that meets the following gradation limits determined in accordance with AASHTO T 27 and FM 1-T011: Table 548-2 Gradation Limits Sieve Size Percent Passing 3-1/2 inches 100 3/4 inch 70-100 No. 4 30-100 No. 40 15-100 No. 100 0-65 No. 200 0-12 For walls not using soil reinforcement, use backfill that meets the following gradation limits determined in accordance with AASHTO T 27 and FM 1-T 011: Table 548-3 Gradation Limits Not Using Soil Reinforcement Sieve Size Percent Passing 3-1/2 inches 100 No. 200 0-12 FY 2023-24 Return to Table of Contents
548-2.6 3 Flowable Fill: Meet the requirements of Section 121 except as noted
within this Section and the Plans.
548-2.6 4 Coarse Aggregate Backfi ll and Drainage Aggregate : Provide coarse
aggregate comprised of natural stones meeting the requirements of Section 901 with a size distribution of any of the listed aggregate gradations from Size No 57 through Size No 89, inclusive, except as noted on the Plans. Have all coarse aggregate backfill materials tested for pH, resistivity, sulfate and chloride content by a Department approved independent testing laboratory prior to placement. Submit a certification , signed and sealed by a Professional Engineer registered in the State of Florida, that the results of these tests meet the requ irements of
548-2.6 2.
For SBW systems, provide drainage aggregate comprised of coarse aggregate backfill and a drainage geotextile to separate the drainage aggregate from the reinforced backfill as specified for each approved wall system .
548-3 Approved Product List (APL).
All proprietary retaining wall systems shall be listed on the APL. Manufacturers seeking evaluation of products for inclusion on the APL shall submit an application in accordance with Section 6, independently certified test reports, and calculations and drawings in accordance with the latest edition of the AASHTO LRFD Bridge Design Specifications and the Department’s Structures Design Guidelines (SDG) signed and seal ed by a Professional Engineer registered in the State of Florida . Submit calculations and drawings showing details, notes, materials, dimensions, sizes, and other information as described below for a complete description of the retaining wall system.
1.Soil reinforcement durability and/or corrosion data ;
2.Differential settlement the wall system can tolerate without exceeding normal stress range of the soil reinforcement and wall facing, or the construction tolerances in this Section;
3.The effects of water flow ;
4.Applicable environmental classifications as outlined in the SDG;
5.Signed and sealed design calculations. Design calculations may be either by hand or by a wall company program with hand calculations verifying the program output. It is only necessary to include sample hand calculations for a 20 foot height for each soil condition.
6.Corrosion and durability design procedures for soil reinforcement elements ;
7.Provide 11 inch x17 inch drawings s howing:
a.Notes specific to the wall system ;
b.Panel sizes and reinforcing ;
c.Soil reinforcement connection to wall facings ;
d.Wall panel abutment interfacing ;
e.Slip joints ;
f.Steps in leveling pad ;
g.Soil reinforcing details around all vertical obstructions ;
h.Filter fabric placement at panel joints and around all obstructions ;
i.Details for skewing soil reinforcement (15 degrees maximum) without cutting;
j.Corner elements (required at all angle breaks greater than 5 degrees);
k.Bin wall details for acute corners (required at all acute corners where interior corner angle is less than 70 degrees); FY 2023-24 Return to Table of Contents
l.Details showing how to accommodate long term (post construction) wall settlement in excess of four inches without attaching soil reinforcement to the abutment ; and,
m.Details of how to ground the wall system .
8.Pull-out test data for the proposed wall/reinforcement connection, and size and type of soil reinforcement for wall system. Testing shall be done by an independe nt soil testing laboratory or testing agency certified by the Department. Ensure test data includes all sizes and types of soil reinforcement to be utilized on Department projects. Default AASHTO values may be used for conventional soil reinforcement. For soil reinforcement grids, include all various configurations and combinations of longitudinal and transverse wires.
9.Other information pertinent to the design and performance of the wall system as necessary.
10.A field construction manual describing construction requirements and sequencing for the wall system. Submit manual in 8 -1/2 inch x 11 inch format in either pdf or MS Word format.
548-4 Shop Drawings.
Submit shop drawings and calculations in accordance with Section 5. Provide calculations and drawings showing details, notes, materials, dimensions, sizes and other information necessary for the complete fabrication and erection of the retaining wall system. As a minimum, provide the following:
1.Elevation view showing the fin ished graded surface and elevations of the top and bottom of wall at the begin and end of wall, all breaks in vertical alignment and all whole stations and 25 foot station increments.
2.Sections showing the length, size and designation of soil reinforcement.
3.Plan view showing the horizontal alignment and offsets from the horizontal control line to the exterior face of the wall; the location of utilities, drainage structures and other items that impact the wall; the limits of the reinforced soil volume; and, the location of piles within the reinforced earth volume.
4.Details for construction around utilities, drainage structures and other items that impact the wall; for placem ent of soil reinforcement at acute corners; for addressing conflicts between soil reinforcement and obstructions in the reinforced soil volume; for addressing different wall types intersecting and impacting each other.
5.General notes and design parame ters including design soil characteristics; factored bearing resistance and factored bearing pressure for each wall height increment and other notes required for construction of the walls.
6.Design calculations for each wall height increment detailed i n the shop drawings.
7.When the friction angle depicted in the shop drawings exceeds 30 degrees for sand backfill or 34 degrees for limerock backfill, provide laboratory test results in accordance with 548 -9.5 verifying the backfill to be used for the wall meets the design soil characteristics for the shop drawings.
8.For SBW systems, include details for the placement of drainage aggregate, drainage pipes and separation geotextile. Drawings should be similar to details for Type II or Type III underdrains in Standard Plans, Index 440-001. Do not directly cover perforated drainage pipes with a geotextile filter fabric (such as a filter sock) .
9.When SBW systems use friction or semi -friction connections between geosynthetic reinforcement and the facing blocks, include the results of connection capacity FY 2023-24 Return to Table of Contents testing. Tests must be performed using the materials to be used on the project and tested in accordance with ASTM D6638 to justify the short -term ultimate connection strength reduction factor (CR u) used to determine the long -term connection strength reduction factor (CR cr) value in the design calculations for each wall height increment detailed in the shop drawings.
548-5 Concrete Component Construction.
Construct reinforced concrete components in accordance with Section 400. Precast wall components are produced using certification acceptance; therefore, assume responsibility for performance of all quality control testing and inspections required by Sections 346 and 400 for the precast component con struction. Perform all quality control (QC) inspection and testing using Construction Training and Qualification Program (CTQP) qualified personnel. Perform compressive strength testing in a laboratory meeting and maintaining at all times the qualification requirements listed in Section 105. The minimum time for form removal is 12 hours. Unless otherwise indicated in the Contract, apply a Class 3 finish to the concrete surface for the front face, and roughly screed the rear face to eliminate open pockets of aggregate and surface distortions in excess of 1/4 inch. Construct unreinforced concrete SBW components (facing blocks) with a minimum compressive strength of 4,000 psi at 28 days and a maximum absorption of 6.5% in accordance with ASTM C140. Units must have a normal weight density classification meeting the requirements of ASTM C1372, except as modified in this Section.
548-5.1 Curing: Cure reinforced concrete components in accordance with Section 400.
548-5.2 Tolerances: Meet the following manufactured tolerances:
548-5.2 1 Reinforced Concrete Components:
1.Precast component dimensions: lateral position of soil reinforcement attachment devices - within 1 inch. All other dimensions - within 3/16 inch.
2.Precast component squareness: angular distortion of the component must not exceed 0.2 inches in 5 feet.
3.Precast component surface finish: surface defects on smooth formed surfaces measured on a length of 5 feet must not exceed more than 0.1 inches. Surface de fects on textured finished surfaces measured on a length of 5 feet must not exceed 5/16 inch.
548-5.2 2 Unreinforced Concrete SBW Components:
1.Length, width and height of each individual block must be within 1/16 inch of the specified dimension. Hol low units must have a minimum wall thickness of 1 - 1/4 inches.
2.All units must be free of defects that would interfere with proper placing of the unit or impair the integrity of the wall construction. Minor cracks with a width less than 1/32 inch and a length less than 25% of the unit height may be acceptable.
3.Exposed facing blocks must be split face texture with a uniform wheat or tan color, unless shown otherwise in the Plans.
548-5.3 Marking of Precast Components:
548-5.3 1 Reinforced Concrete Components: Permanently and legibly mark the
following information on the back of each reinforced precast wall panel by etching: the panel number or type, piece mark, project number (if applicable), date cast and precast manufacturer’s name or symbol with the approved producer’s QC stamp affixed.
548-5.3 2 Unreinforced Concrete SBW Components: Label each pallet of dry -
cast unreinforced concrete SBW facing blocks with the component identification number or type, FY 2023-24 Return to Table of Contents project number (if appli cable), LOT number, date cast, and the manufacturer’s name or symbol. Labels must be clearly legible until the component is installed.
548-6 Repairs or Rejection of Precast Components.
548-6.1 Reinforced Concrete Components: For precast concrete wall comp onents that
have not been installed, evaluate cracks, spalls and other deficiencies in accordance with 450 -12. Repair deficiencies in accordance with 450 -13 or the plant’s approved repair methods that are included as part of the Producer Quality Control Pl an. The original performance and durability of repaired wall components must be maintained. Use materials for concrete repair that meet or exceed the strength requirement for the class of concrete used. Materials meeting the requirements of Section 930 may be substituted for non shrink grout when required by 450 -13. For precast concrete wall components that have been installed, the disposition of concrete cracks will be determined in accordance with 400 -21. The Department will reject all precast concret e wall components not meeting the quality standard of this Section and referenced Specifications. In addition, any of the following defects will be sufficient cause for rejection by the Department:
1.Defects that indicate unsatisfactory molding.
2.Defects indicating honeycombed or open texture concrete.
3.Defects in the physical characteristics such as:
a.Signs of aggregate segregation
b.Broken or cracked corners
c.Soil reinforcement attachment devices improperly installed/damaged
d.Lifting inserts not useable
e.Exposed reinforcing steel
f.Insufficient cover over reinforcing steel
g.Cracks at the alignment pipe or pin
h.Insufficient concrete compressive strength
i.Precast component thi ckness in excess of plus or minus 3/16 inch from that shown in the Contract Documents
j.Stained front face, due to excess form oil or other reasons. If the face of the precast component is stained or discolored to the point of rejection, the stain or discoloration may be removed , or a Department approved stain or a Class 5 finish may be applied to attain a uniform appearance for the entire structure, to the satisfaction of the Engineer.
548-6.2 Unreinforced Concrete SBW Components: The Department will reject all
segmental retaining wall blocks not meeting the requirements of this Section and the Contract Documents. In addition, any of the following defects will be sufficient cause for rejection of SBW facing blocks by the Department:
1.Defects that indicate unsatisfactory molding.
2.Defects indicating honeycombed or open texture concrete.
3.Defects in the physical characteristics such as:
a.Signs of aggregate segregation
b.Broken or cracked corners
c.Insufficient concrete comp ressive strength d, Excessive concrete absorption
e.Exceeding dimensional tolerances , or
f.Discoloration. FY 2023-24 Return to Table of Contents Correct cracks or spalls occurring after installation in accordance with 400 -21.
548-7 Handling Storage and Shipping.
Handle, store a nd ship all components in a manner that prevents chipping, cracks, fractures, excessive bending stresses, mud, dirt and debris. Support precast panel wall and counterfort components in storage on firm blocking located immediately adjacent to the attachment device. Do not ship precast concrete wall components to the project site prior to the completion of the 72 hour curing period and attainment of the required 28 day strength. The Contractor is permitted to verify the shipping strength test, before 28 days, by testing compressive strength cylinders that are cured under the conditions similar to the product or by testing temperature match cured cylinders. The shipping strength test is the average compressive strength of two test cylinders. Do not ship reinforced concrete products until accepted and stamped by the QC Manager or the inspectors under the direct observation of the QC Manager.
548-8 Construction Requirements.
548-8.1 General: Due to the unique nature of the structure and concept, procure from the
wall supplier fully detailed shop drawings, technical instructions, guidance in preconstruction activities and on -site technical assistance during construction. Closely follow any instructions from the wall supplier, unless otherwise directed by t he Engineer. Submit any instructions from the wall supplier to the Engineer. Verify all pertinent retaining wall information (soil parameters, wall alignment, utility locations, conflicting structures) prior to the wall supplier finalizing shop drawings. B ring any conflicts not shown in the Contract to the Engineer’s attention.
548-8.2 Wall Excavation: Excavate to the limits shown in the Contract and in
conformance with Section 125.
548-8.3 Foundation Preparation: Grade the foundation for the structure le vel for a
width equal to or exceeding the limits of the retaining wall volume or as shown in the Contract. Prepare the foundation in conformance with Section 125. In addition to the compaction requirements of Section 125, compact the graded area with an appropriate vibratory roller weighing a minimum of eight tons for at least five passes or as directed by the Department’s District Geotechnical Engineer. Remove and replace any soft or loose foundation subsoils incapable of sustaining the required compacti on to the Engineer’s satisfaction. For permanent MSE wall systems, provide an unreinforced concrete leveling pad as shown in the Contract Documents . Cure the leveling pad a minimum of 12 hours before placement of precast wall components. For SBW MSE wa ll systems, a geogrid reinforced, geotextile wrapped, compacted aggregate leveling pad may be used in lieu of the unreinforced concrete leveling pad. The compacted aggregate leveling pad must be at least 24 inches wide and at least 8 inches thick after com pacting, and the geogrid must be at least 6 inches below the top of the leveling pad. Wrap the aggregate leveling pad with a D -2, D-3, or D-5 separation geotextile. The geotextile may run up the front and back of the first block course or between the aggre gate leveling pad and the first block course.
548-8.4 Wall Erection: Assemble, connect and support wall components as
recommended by the wall supplier. As backfill material is placed behind the wall face of MSE wall systems utilizing reinforced concrete p anels, maintain the wall in the vertical position or slightly battered into the backfill to provide a final vertical alignment (by means of bracing, FY 2023-24 Return to Table of Contents temporary wooden wedges placed in the joint at the junction of the two adjacent precast components on the e xternal side of the wall or other alignment aids). Remove wooden wedges as soon as the precast component above the wedged precast component is completely erected and backfilled. External bracing is required for the initial lift of MSE systems. For SBW sy stems, carefully place the first course of concrete block units on the leveling pad. Up to 1/2 inch of sand may be placed between the concrete leveling pad and the buried first course of blocks to provide a level and stable base. A one inch gap between the first course of facing units is allowed, provided a suitable filter fabric is placed behind the foundation units as specified for each approved wall system . Each unit must be in full contact with the base and checked for level and horizontal alignment. Voids must be kept to a minimum to prevent point loading and cracking, unless otherwise indicated in the shop drawings. Place units side by side for the full length of wall alignment. Fill the hollow cores or cells and the space within blocks with drainage a ggregate. Sweep away excess material from top of units and install the next course. Place soil reinforcement normal to the face of the wall, unless otherwise shown in the Contract or as directed by the Engineer. Do not cut or kink soil reinforcement. Do not connect soil reinforcement to piles or allow soil reinforcement to bear against piles. Field cut soil reinforcement only at locations as shown in the approved shop drawings. Prior to p lacement of the reinforcement, compact the backfill in accordance with 548 -8.5. For SBW systems, shims made of non -degradable materials may be used as specified for each approved wall system . The shim thickness per course of block must not exceed 1/8 inch and must not be installed on reinforcement elevations when the reinforcement connection relies on any friction .
548-8.4 1 Tolerances for Permanent Walls: Walls that do not meet the
following tolerances will not be accepted by the Department and must be removed and reconstructed at no cost to the Department.
548-8.4 1.1 Reinforced Concrete MSE Wall Systems: Vertical
tolerances (plumbness) and horizontal alignment tolerances must not exceed 3/4 inch when measured with a 10 foot straightedge. The maximu m allowable offset in the joint between precast components is 3/4 inch. The final overall vertical tolerance of the completed wall (plumbness from top to bottom) must not exceed 1/2 inch per 10 feet of wall height. Horizontal and vertical joints between pr ecast components must not be less than 1/2 inch or more than 1 - 1/4 inches.
548-8.4 1.2 SBW Systems: Horizontal alignment tolerances must
not exceed 3/4 inch per10 feet of wall length. The maximum allowable gap between segmental retaining wall blocks ab ove the first course must not exceed 1/ 16 inch. The final overall vertical tolerance of the completed wall (deviation from plumbness from top to bottom or batter shown in the Plans) must not exceed 1/2 inch per 10 feet of wall height.
548-8.4 2 Tolerance s for Temporary Walls: Vertical tolerances (plumbness)
and horizontal alignment tolerances must not exceed three inches when measured with a 10 foot straightedge. The final overall vertical tolerance of the completed wall (plumbness from top to bottom) must not exceed one inch per three feet of wall height, not to exceed a total of six inches.
548-8.5 Backfill Placement:
548-8.5 1 Compacted Selec t and Coarse Aggregate Backfill: A LOT is defined
as a single lift of finished embankment not to exceed 500 feet in length of continuous or FY 2023-24 Return to Table of Contents interconnected walls. Backfill within 3 feet from the panels and backfill beyond 3 feet from the panels are separate LOTs. Overlapping retaining wall volumes may be considered one LOT, excluding the 3-foot width behind the panels. Strips up to 8 feet wide between two retaining wall volumes constructed with the same material in a single operation may be considered as one LOT with the retaining wall volumes. Isolated compaction operations will be considered as separate LOTs. For multiple phase construction, a LOT will not extend beyond the limits of the phase. When bridge abutments on spread footings are shown in the Plans , the material within 3 feet behind the wall face and within the limits defined in 548 -9.4.2 are considered as separate LOTs. Remove wrinkles in geo synthetic reinforcement prior to covering with backfill. Place the backfill closely following the erectio n of each course of precast components or soil reinforcement layers and spread by moving the machinery parallel to the wall face. Do not allow equipment heavier than eight tons closer than three feet behind the wall face. Place backfill in a manner to avoi d any damage or disturbance to the wall materials or misalignment of the facing materials. Remove and replace any wall materials which become damaged or disturbed during backfill placement at no cost to the Department, or correct as directed by the Enginee r. Remove and reconstruct any misalignment or distortion of the wall facing due to placement of backfill outside the limits of this specification at no cost to the Department. Compact coarse aggregate backfill with a minimum of three passes of a vibratory compactor weigh ing between 600 and 1000 pounds or two passes of vibratory compactor weighing over 1000 pounds. Use the highest vibration level that does not cause excessive fracture of the aggregate in the opinion of the Engineer. Continue compaction until there is no additional movement. Sheepsfoot, grid rollers or other types of equipment employing a foot are not allowed for any backfill type . Achieve compaction of all backfill types within three feet of the back of the wall face using a power operated roller or plate weighing less than 1,000 pounds. At a distance greater than three feet from the back of the wall, a vibratory roller may be used, provided that the frequency and amplitude combined with bulk weight of the roller has performed satisfactorily at a trial section of the same type of wall. For select backfill, a smooth wheel or rubber tire roller is consid ered adequate. For walls employing geosynthetic reinforcement, limit the weight of compaction equipment to 25,000 pounds. Ensure that the maximum lift thickness after compaction does not exceed six inches. Decrease the lift thickness if necessary, to obtai n specified density. All transitions from coarse aggregate backfill to select backfill must occur at least six inches above and below any layers of backfill reinforcement. Place a separation geotextile in accordance with 548 -2.5.4 between the coarse agg regate backfill and select backfill and embankment. Perform backfill compaction in a way that the compactor moves in a direction parallel to the wall face and proceeds from a distance not less than three feet behind the wall face toward the end of the s oil reinforcement element. When placing select backfill, the moisture content of the backfill material prior to and during compaction must be uniformly distributed throughout each layer of material. Use backfill material having a placement moisture cont ent at the dry side of the optimum moisture content. To achieve the required compaction moisture content, use water that meets the requirements of Section 923. Do not transport excessively moist backfill materials to the site for any reason. Determine the optimum moisture content in accordance with the test method used to determine maximum density in 548 -9. FY 2023-24 Return to Table of Contents At the end of each day’s operation, shape the last level of backfill to permit runoff of rainwater away from the wall face or provide a positive mean s of controlling run off away from the wall such as temporary pipe.
548-8.5 2 Thick Lift Option for Compacted Select Backfill: If through field
tests, the Contractor can demonstrate that the compaction equipment can achieve density for the full depth of a thicker lift, the backfill may be constructed in successive courses of not more than 10 inches compacted thickness. Based on the results of a full -height test wall constructed by each Contractor or MSE wall sub -contractor, the Engineer will approve each Contractor’s or MSE wall sub-contractor’s specified compaction procedures . The length of the test wall shall be the length required to produce one LOT of 500 feet at the top of the wall. When all individual walls using this option are less than 500 -feet long, the test wall may be broken into two segments comprising separate LOTs. Both segments must be accepted to determin e the required percent compaction for the remaining walls. For each Contractor or MSE wall sub -contractor, the height of the test wall shall be 20 feet or the highest wall using this option , whichever is less. Lower height walls may be constructed using th ese procedures until a full height test wall is constructe d. Notify the Engineer prior to beginning construction of a test wall. Perform one set of QC density tests per thick lift of the test wall on the backfill within three feet behind the wall face a nd one set of QC density tests per thick lift of the test wall on the backfill placed beyond three feet behind the wall face, at random locations within each LOT. At each QC density test, the set will include testing the entire lift thickness and a dig down test of the bottom 6 inches. Excavate materials as needed to allow testing of the bottom 6 inches, at no expense to the Department. Maintain the exposed surface as close to undisturbed as possible; no further compaction will be permitted during the test preparation. The Department will perform verification testing of density for the bottom 6 inches and the entire lift thickness at the frequency indicated in 548 -9.6. All QC tests and a Department Verification test must meet the density required by 548 -9.4. Identify the test wall with the required percent compaction effort and thickness in the Earthwork Records System (ERS) portion of the Department’s database . If the thick lift density does not meet or exceed the thick lift density results during the tes t wall, perform dig -down density tests to verify the density of the bottom 6 inches of the lift. The Contractor may elect to place material in 6 inches compacted thickness at any time. Once approved, a change in the source of backfill material will require the construction of a new test wall. Do not change the compaction effort once the test wall is approved. The Engineer will periodically verify the density of the bottom 6 inches during thick lift operations. If unable to achieve the required density, remo ve and replace or repair the test wall to comply with the specifications at no additional expense to the Department. The Engineer may terminate the use of thick lift construction and instruct the Contractor to revert to the 6 inches maximum lift thickness if the Contractor fails to achieve satisfactory results or meet the requirements of this Section.
548-8.5 3 Flowable Fill: Metallic wall components (including metallic soil
reinforcements) must not be in partial contact with the flowable fill. If the metallic components contact the flowable fill, the metallic components must be completely encapsulated by the flowable fill.
548-8.6 Compressible Free Draining Seal: Seal all joints between panels of reinforced
concrete panel MSE walls with compressible free draining material (open cell) to prevent plant growth from seeds or spores that may be in the joints or transported to the joints by wind or rain. FY 2023-24 Return to Table of Contents Install the seal at least 1-1/2-inches from both the front and rear faces of the panel. Protect the free draining seal during the application of coatings and sealants. Should the seal become coated or clogged, remove and replace the coated or clogged free draining seal. The installation must be secure and free draining to keep the seal securely in place until uninstalled and to prevent hydrostatic forces from building up behind the panel.
548-9 Acceptance Program.
548-9.1 General Re quirements: Meet the requirements of 120 -10 except delete the
requirements of 120 -10.1.4.1, 120 -10.1.4.3, 120 -10.1.6, 120 -10.2 and 120 -10.3.
548-9.2 Maximum Density Determination: For select backfill, determine the maximum
QC density in accordance with FM 1-T180. When compacting A -3 or A-2-4 materials to meet the alternate acceptance criteria in 548 -9.4.1, determine the maximum density in accordance with FM 1-T099. Perform gradation tests on the sample collected in accordance with AASHTO T 27 and FM 1-T011. Classify soils in accordance with AASHTO M 145 to determine compliance with embankment utilization requirements.
548-9.3 Density Testing Requirements: Ensure compliance with the requirements of
nuclear density testing in accordance with FM 1-T238. Det ermine the in -place moisture content for each density test. Use FM 1-T238, FM 5-507 (Determination of Moisture Content by Means of a Calcium Carbide Gas Pressure Moisture Tester), or FM 5-535 (Laboratory Determination of Moisture Content of Granular Soils by Use of a Microwave Oven) for moisture determination. Perform these tests at a minimum frequency of one set of tests per LOT. Determine test locations including stations and offsets, using the random number generator provided by the Engineer. Do not use notepads or worksheets to record data for later transfer to the ERS section of the Department’s database . Notify the Engineer up on successful completion of QC testing on each LOT.
548-9.4 Acceptance Criteria: For select backfill, o btain a minimum density of 90% of
the maximum dry density as determined by FM 1-T180 within three feet behind the wall face and obtain a minimum density of 95% of the maximum dry density as determined by FM 1-T180 from beyond three feet behind the wall face. For flowable fill, meet the requirements of 121 -6. For coarse aggregate backfill, compact with a minimum of three passes of a vibratory compactor w eighing between 600 and 1000 pounds or two passes of a vibratory compactor weighing over 1000 pounds. Use the highest vibration level that does not cause excessive fracture of the aggregate in the opinion of the Engineer. Continue compaction until there is no additional movement.
548-9.4 1 Optional Acceptance Criteria for A -3 and A-2-4 Materials: Obtain a
minimum density of 95% of the maximum dry density as determined by FM 1-T099 within 3 feet behind the wall face and obtain a minimum density of 100% of the maximum dry density as determined by FM 1-T099 beyond 3 feet behind the wall face. The combined width from both MSE wall backfill (excluding the 3-foot zone from the panels) and embankment material may be considered the same LOT if the same material is used; the material in both wall backfill and embankment is compacted with the same procedure, equipment and compacting effort; and the maximum lift thickness after compaction in both wall backfill and embankment is 6-inches.
548-9.4 2 Acceptance Crit eria for Wall Backfill Supporting Spread Footings:
When spread footings at bridge abutments are shown in the Plans, obtain a minimum of 95% of FY 2023-24 Return to Table of Contents the maximum dry density as determined by FM 1-T180 on the material within 3 feet behind the wall face, and undern eath the footing as defined by the following limits:
1.All lifts below the bottom of the footing for a depth equal to at least the footing width
2.A minimum distance of 3 feet beyond the edges of the footing width If the optional criteria specif ied in 548 -9.4.1 is used, compact the backfill material within the limits specified above to obtain a minimum density of 100% of the maximum dry density as determined by FM 1-T099. Compact the remainder of the backfill in accordance with 548-9.4 or 548 -9.4.1 as applicable. Do not use compaction equipment larger than permitted in 548-8.5 within 3 feet behind the wall face; decrease the lift thickness if necessary.
548-9.5 Friction Angle: When the friction angle depicted in the shop drawings exceeds
30 degrees for sand backfill or 34 degrees for limerock backfill, ensure the friction angle of the backfill material tested in accordance with FM 3-D3080 equals or exceeds the backfill friction angle depicted in the shop drawings.
548-9.6 Frequency: Conduct sampling and testing at a minimum frequency listed in the
table below. The Engineer will perform verification sampling and tests at a minimum frequency listed in Table 548 -4 below. Table 548-4 Minimum Frequency Testing Test Name Quality Control (QC) Verification Maximum Density One per soil type One per soil type Density One per LOT One per four LOTs for each type of QC test Gradation One per Maximum Density One per Maximum Density LL&PI One per Maximum Density One per Maximum Density Soil Classification One per Maximum Density One per Maximum Density Organic Content One per soil type One per soil type pH One per soil type One per soil type Direct Shear Three per soil type when required by 548-9.5 One per soil type *Verification testing for pH will be performed on samples taken at the point of placement. In addition, for permanent walls utilizing metallic soil reinforcement, test for corrosiveness at a minimum frequency of one test per soil type at point of placement according to the electro -chemical table in 548 -2.6. The Engineer will collect enough material to split and create two separate samples and retain one for resolution at point of placement until LOTs represented by the samples are accepted. The Eng ineer will perform verification tests for corrosiveness at a minimum frequency of one test per soil type.
548-9.7 Verification Comparison Criteria and Resolution Procedures:
548-9.7 1 Maximum Density Determination: The Engineer will collect enough
material to split and create two separate samples and retain one for resolution until LOTs represented by the samples are accepted. FY 2023-24 Return to Table of Contents The Engineer will meet the requirements of 120 -10.4.1 except replace FM 1-T099 with FM 1-T180. If the Contractor selects the Optional Acceptance Criteria, the Engineer will verify the QC results of FM 1-T099 in accordance with 120 -10.4.1.
548-9.7 2 Density Testing: Meet the requirements of 120 -10.4.2.
548-9.7 3 Soil Classification: The Engineer will meet the requirements of
120-10.4 3 except test the sample retained in 548 -9.7.1 instead of taking the additional one.
548-9.7 4 Gradation: The Engineer will verify the QC results if the verification
result meets the gradation limits set for th in the gradation table of 548 -2.6. Otherwise, the Engineer will test the sample retained in 548 -9.7.1. The State Materials Office (SMO) or an AASHTO accredited laboratory designated by the SMO will perform resolution testing. The material will be sample d and tested in accordance with AASHTO T 27 and FM 1-T011. If the resolution test result satisfies the required gradation limits, the LOTs will be verified. If the resolution test results do not meet the required gradation limits, reconstruct the LOTs with acceptable material. The Engineer will perform new verification testing.
548-9.7 5 Liquid Limit and Plasticity Index (LL&PI): The Engineer will verify
the QC results if the verification result satisfies the plasticity index and liquid limit criteria set forth in 548 -2.6. Otherwise, the Engineer will test the sample retained in 548 -9.7.1. The SMO or an AASHTO accredited laboratory designated by the SMO will perform resolution testing. The material will be sampled and tested in accordance with AASHTO T 90 and AASHTO T 89, respectively. If the resolution test result satisfies the required criteria, LOTs of that soil type will be verified. If the resolution test results do not meet the required criteria, reconstruct the corresponding LOTs with acceptabl e material. The Engineer will perform new verification testing.
548-9.7 6 Corrosiveness: The Engineer will verify the QC results if the
verification result satisfies the electro -chemical and pH test criteria set forth in 548 -2.6. Otherwise, the Engineer will test the sample retained in 548 -9.7.1. The SMO or an AASHTO accredited laboratory designated by the SMO will perform resolution testing. The material will be sampled and tested in accordance with FM 5-550, FM 5-551, FM 5-552 and FM 5-553. If the resolution test result satisfies the required criteria, material of that soil type will be verified and accepted. If the resolution test results do not meet the required criteria, reject the material and reconstruct with acceptable material.
548-9.7 7 Orga nic Content: The Engineer will verify the QC results if the
verification result satisfies the organic content test criteria set forth in 548 -2.6. Otherwise, the Engineer will collect three additional samples. The material will be sampled and tested in accordance with FM 1-T267 and by averaging the test results for three randomly selected samples from at least one lift per soil type. The SMO or an AASHTO accredited laboratory designated by the SMO will perform resolution testing. If the resolution test res ult satisfies the required criteria, material of that soil type will be verified and accepted. If the resolution test results do not meet the required criteria, reject the material and reconstruct with acceptable material.
548-9.7 8 Friction Angle: When the friction angle depicted in the shop drawings
exceeds 30 degrees for sand backfill or 34 degrees for limerock backfill, the Engineer will take a verification sample at the point of placement to perform a direct shear verif ication test in accordance with FM 3-D3080. The SMO or a consultant qualified to perform geotechnical FY 2023-24 Return to Table of Contents specialty lab testing (Type of Work 9.5), per Rule 14 -75 of the Florida Administrative Code will perform the verification testing. If the test verifies th e material has a friction angle greater than or equal to the friction angle depicted in the shop drawings, the material in the LOTs will be verified. If the verification test does not meet the required friction angle, reconstruct the LOTs with acceptable m aterial. The Contractor may request to redesign the wall and resubmit the shop drawings with the lower friction angle indicated by the verification test. Employ a Professional Engineer to redesign and submit signed and sealed drawings and computations. Do not begin any reconstruction until the proposed redesign has been reviewed and approved by the Engineer. The Contractor shall bear the costs of the redesign and any work resulting from the design changes.
548-10 Certification.
Submit all test reports to the Engineer necessary to document compliance with the Specifications, at least ten days prior to wall construction. Also submit a certificate of compliance certifying that the retaining wall materials, backfill and construction practices comply with th is Section. For SBW systems, the Engineer will randomly select samples of each type of block used in the segmental block retaining wall system and review a copy of the certified test report corresponding the sample at a frequency of one sample per type of block for each wall. Acceptance of furnished material will be based on the certificate of compliance, accompanying test reports, and visual inspection by the Engineer.
548-11 Method of Measurement.
The quantity to be paid for will be the plan quantity, in square feet, completed and accepted, of the area bounded by the following: For permanent retaining wall systems: the top of the coping, the top of the leveling pad or top of structural footings and the begin and end wall limits as shown on the wall control drawings. For temporary retaining wall systems: the top of wall , the ground line and the begin and end wall limits as shown on the wall control drawings.
548-12 Basis of Payment.
Price and payment will be full compensation for all work specified in this Section, including the design of the wall system, excavation required specifically for wall construction below the finished graded surface , backfill reinforcement, leveling pad, foo tings, copings, light pole pedestals, fabric material, horizontal joint materials, alignment pins, repairs, labor, equipment, and other materials necessary to complete the wall in an acceptable manner as shown in the Contract. The cost of backfill for the finished graded surface will be included in the cost of embankment or borrow excavation, as applicable. Payment will be made under: Item No. 548 - 12- Retaining Wall System (Permanent) - per square foot. Item No. 548 - 13- Retaining Wall System (Temporary) - per square foot. FY 2023-24 Return to Table of Contents SECTION 550 FENCING
550-1 Description.
Furnish, erect and reset metal fence of the type and at the locations shown in the Plans.
550-2 Types of Fence.
The types of fence are designated as follows: Type A (Farm Fence). Type B (Chain-Link Fence). Type R (Chain-Link Fence for Pedestrian Overpass).
550-3 Materials.
550-3.1 Type A Fence (Farm Fence): Meet the requirements of Section 954 for timber
posts and braces. For metal posts and braces, and for recycled plastic fence posts, meet the requirements of the Standard Plans . For the fabric and all other accessories, meet the requirements of the Standard Plans.
550-3.2 Type B Fence (Chain -Link): For the posts, braces, fabric and all accessories
other than the concrete for bases, meet the re quirements of the Standard Plans . Use concrete as specified in Section 347, or a premix approved by the Engineer for bases. The requirements contained in 347 -2.2, and 347 -3 will not apply.
550-3.3 Type R Fence (Chain -Link for Pedestrian Overpass): Use the fabric and
accessories specified in the Plans.
550-3.4 Resetting Fence: Use material from the existing fence. For any additional
materials required, provide the same type of material as in the existing fence and as specified herein, including gates whe n applicable.
550-3.5 Optional Use of Materials: For Type A Fence, a combination of steel,
aluminum, timber, recycled plastic or concrete posts may be used. Unless otherwise called for in the Plans, line posts of one material may be used with corner, pull and end post assemblies of a different material. The Engineer will permit the use of line posts of only one optional material and pull posts assemblies of only one optional material between corner and end post assemblies. Within individual corner and end post assemblies, the Engineer will allow the use of only one optional material. For Type B Fence, a combination of zinc -coated steel fence members, aluminum coated fence members and aluminum alloy fence members may be used. Unless otherwise indicated in the Plans, the Engineer will allow the use of only one type of fabric material, one type of line post material and one type of pull assembly material between corner and end post assemblies.
550-3.6 Certification: Provide the Engineer with certified test r eports from the
manufacturer confirming that all materials (posts, braces, fabric and all other accessories) conform to the requirements of this Section, Section 6 and the Standard Plans . Provide the Engineer a copy of the certification at least ten days p rior to fence construction. Also furnish the Engineer a Certificate of Compliance certifying that the fencing system, materials and construction practices comply with the applicable Standard Plans and Specifications. FY 2023-24 Return to Table of Contents
Source: Florida Standard Specifications for Road and Bridge Construction, 2024 Edition. Pages 767–782 of 1,299.