M 41-10 Page 6-2236-11 Reinforced Concrete Walls
6-11.1 Description
This Work consists of constructing reinforced concrete retaining walls, including those shown in the Standard Plans .
6-11.2 Materials
Materials shall meet the requirements of the following sections: Cement 9-01 Aggregates for Concrete 9-03.1 Gravel Backfill 9-03.12 Premolded Joint Filler 9-04.1(2) Steel Reinforcing Bar 9-07.2 Epoxy-Coated Steel Reinforcing Bar 9-07.3 Concrete Curing Materials and Admixtures 9-23 Fly Ash 9-23.9 Water 9-25 Other materials required shall be as specified in the Special Provisions.
6-11.3 Construction Requirements
6-11.3(1) Submittals
All components of reinforced concrete retaining walls, regardless of the combination of precast and cast-in-place components shall be submitted simultaneously as a comprehensive submittal. The Contractor shall submit Type 2E Working Drawings consisting of excavation shoring plans in accordance with Section 2-09.3(3)D . The Contractor shall submit Type 2E Working Drawings of falsework and formwork plans in accordance with Sections 6-02.3(16) and 6-02.3(17) . If the Contractor elects to only fabricate and erect precast reinforced concrete wall stem panels in place of the cast-in-place Standard Plan wall stems, Type 2E Working Drawings of the following information shall be submitted in accordance with Section 6-02.3(9)A :
1.Working drawings for fabrication of the wall stem panels, showing dimensions, steel reinforcing bars, joint and joint filler details, surface finish details, lifting devices with the manufacturer’s recommended safe working capacity, and material Specifications.
2.Working drawings and design calculations for the erection of the wall stem panels showing dimensions, support points, support footing sizes, erection blockouts, member sizes, connections, and material Specifications.
3.Design calculations for the precast wall stem panels, the connection between the precast panels and the cast-in-place footing, and all modifications to the cast-in-place footing details as shown in the Plans or Standard Plans .
4.Cast-in-place submittal requirements for foundations in accordance with Section
6-11 3(1)A.
Reinforced Concrete Walls 6-11 Page 6-224 M 41-106-11.3(2) Excavation and Foundation Preparation Excavation shall conform to Section 2-09.3(3) , and to the limits and construction stages shown in the Plans. Foundation soils found to be unsuitable shall be removed and replaced in accordance with Section 2-09.3(1)C .
6-11.3(3) Precast Reinforced Concrete Wall Stem Panels
The Contractor may fabricate precast reinforced concrete wall stem panels for construction of Standard Plan Retaining Walls. Precast reinforced concrete wall stem panels may be used for construction of non-Standard Plan retaining walls if allowed by the Plans or Special Provisions. Precast reinforced concrete wall stem panels shall conform to Section 6-02.3(9) except as modified in this section, and shall be cast with Class 4000 concrete. The precast concrete wall stem panels shall be designed in accordance with the following codes:
1.For all loads except as otherwise noted – AASHTO LRFD Bridge Design Specifications , latest edition and current interims. The seismic design shall use the acceleration coefficient and soil profile type as specified in the Plans.
2.For all wind loads – AASHTO Guide Specifications for Structural Design of Sound Barriers, latest edition and current interims. The precast reinforced concrete wall stem panels shall be fabricated full height, and shall be fabricated in widths of 8, 16, and 24 feet. The construction tolerances for the precast reinforced concrete wall stem panels shall be as follows: Height ±¼ inch Width ±¼ inch Thickness +¼ inch -⅛ inch Concrete cover for steel reinforcing bar +⅜ inch -⅛ inch Width of precast concrete wall stem panel joints ±¼ inch Offset of precast concrete wall stem panels ±¼ inch (Deviation from a straight line extending 5 feet on each side of the panel joint) The precast concrete wall stem panels shall be constructed with a mating shear key between adjacent panels. The shear key shall have beveled corners and shall be 1½ inches in thickness. The width of the shear key shall be 3½ inches minimum and 5½ inches maximum. The shear key shall be continuous and shall be of uniform width over the entire height of the precast reinforced wall stem panel. The Contractor shall provide the specified exterior concrete surface finish as noted, and to the limits shown, in the Plans. Surface finishes achieved with form liners shall conform to Sections 6-02.2 and 6-02.3(14) as supplemented in the Special Provisions. Rolled on textured finished shall not be used. Precast reinforced concrete wall stem panels shall be cast in a vertical position if the Plans call for a form liner texture on both sides of the precast reinforced concrete wall stem panel. The precast reinforced concrete wall stem panel shall be rigidly held in place during placement and curing of the cast-in-place footing concrete. The precast reinforced concrete wall stem panels shall be placed a minimum of 1 inch into the cast-in-place footing to provide a shear key. The base of the precast reinforced concrete wall stem panel shall be sloped ½ inch per foot to facilitate proper concrete placement.
6-11 Reinforced Concrete Walls
M 41-10 Page 6-225To ensure an even flow of concrete under and against the base of the precast reinforced concrete wal l stem panel, a form shall be placed parallel to the precast reinforced concrete wall stem panel, above the cast-in-place footing, to allow a minimum 1-foot head to develop in the concrete during concrete placement.The steel reinforcing bars shall be shifted to clear the erection blockouts in the precast concrete wall stem panel by 1½ inches minimum. All precast reinforced concrete wall stem panel joints shall be constructed with joint filler installed on the rear (backfill) side of the wall. The joint filler material shall extend from 2 feet below the final ground level in front of the wall to the top of the wall. The joint filler shall be a nonorganic flexible material and shall be installed to create a waterproof seal at panel joints. The soil bearing pressure beneath the falsework supports for the precast reinforced concrete wall stem panels shall not exceed the maximum design soil pressure shown in the Plans for the reinforced concrete retaining wall.
6-11.3(4) Cast-In-Place Concrete Construction
Cast-in-place reinforced concrete for concrete retaining walls shall be formed, reinforced, cast, cured, and finished in accordance with Section 6-02 , and the details shown in the Plans and Standard Plans . All cast-in-place concrete shall be Class 4000 or as shown in the Plans. Cast-in-place footings shall have a longitudinal slope no steeper than 1V: 6H, unless otherwise shown in the Plans or Standard Plans . The Contractor shall provide the specified exterior concrete surface finish as noted, and to the limits shown, in the Plans. Surface finishes achieved with formliners shall conform to Sections 6-02.2 and 6-02.3(14) as supplemented in the Special Provisions. Cast-in-place concrete for adjacent wall stem sections (between vertical expansion joints) shall be formed and placed separately, with a minimum 24-hour time period between concrete placement operations. Premolded joint filler, ½ inch thick, shall be placed full height of all vertical wall stem expansion joints in accordance with Section 6-01.14 .
6-11.3(5) Backfill, Weepholes, and Gutters
Unless the Plans specify otherwise, backfill and weepholes shall be placed in accordance with the Standard Plans and Section 6-02.3(22) . Gravel backfill for drain shall be compacted in accordance with Section 2-09.3(1)E . Backfill within the zone defined as Bridge Approach Embankment in Section 1-01.3 shall be compacted in accordance with Method C of Section 2-03.3(14)C . All other backfill shall be compacted in accordance with Method B of Section 2-03.3(14)C , unless otherwise specified. Cement concrete gutter shall be constructed as shown in the Plans or Standard Plans .
6-11.3(6) Traffic Barrier and Pedestrian Barrier
When shown in the Plans, traffic barrier and pedestrian barrier shall be constructed in accordance with Sections 6-02.3(11)A and 6-10.3(2) , and the details shown in the Plans and Standard Plans .
6-11.4 Measurement
Concrete Class 4000 for retaining wall will be measured as specified in Section
6-02.4 Steel reinforcing bar for retaining wall and epoxy-coated steel reinforcing bar for
retaining wall will be measured as specified in Section 6-02.4 . Reinforced Concrete Walls 6-11 Page 6-226 M 41-106-11.5 Payment Payment will be made for each of the following Bid items when they are included in the Proposal: “Conc. Class 4000 For Retaining Wall”, per cubic yard. All costs in connection with furnishing and installing PVC pipe for weep holes, premolded joint filler, grout, exterior surface finish, and pigmented sealer (when specified), shall be included in the unit Contract price per cubic yard for “Conc. Class 4000 for Retaining Wall”. “St. Reinf. Bar For Retaining Wall”, per pound. “Epoxy-Coated St. Reinf. Bar For Retaining Wall”, per pound. Traffic and Pedestrian Barrier shall be paid for in accordance with Section 6-10.5.
6-11 Reinforced Concrete Walls
Source: Washington Standard Specifications for Road, Bridge, and Municipal Construction, 2024 Edition. Pages 577–580 of 1,151.