Category:1052 Mechanically Stabilized Earth Wall (MSE) and Sound Wall System Components

From Engineering Policy Guide

Jump to: navigation, search
An excavator operator carries more steel straps to a MSE wall being constructed
An excavator operator carries more steel straps to a MSE wall being constructed
MGS Information
Current General Services Specifications (MGS) By Subject

This article establishes procedures for inspecting, acceptance and reporting of MSE and Sound Wall System Components. Refer to Sec 1052 and Sec 720 for MoDOT’s specifications.

Contents

1052.1 Apparatus

a) Rule with suitable graduations to accurately measure the material to be inspected.
b) Applicable AASHTO specifications.
c) Approved shop drawings.

1052.2 Procedure

1052.2.1 Metallic Soil Reinforcement

The destination district is responsible for acceptance of metallic soil reinforcement. The manufacturer of the wall system shall certify in writing that the soil reinforcement, connections and fasteners meet the minimum requirements directed by the design and this specification. The contractor shall provide this certification and any other supporting documentation to the engineer prior to the material being delivered to the construction site.

1052.2.2 Non-Metallic Soil Reinforcement

The destination district is responsible for acceptance of non-metallic soil reinforcement. The manufacturer of geogrid shall certify in writing that the geogrid is in accordance with this specification. The certification shall include the roll numbers and identification, the sampling procedures, the results of the quality control tests along with the tests used, and the Minimum Average Roll Value (MARV) for each roll used to construct the wall. This certification and any other supporting documentation shall be provided to the engineer prior to the material being delivered to the construction site.

1052.2.3 Large Block Wall and Sound Wall System Procedure

The producing district is responsible for acceptance of large block and sound wall panels and posts. Acceptance of precast panels and posts shall be on the producer’s adherence to their producer quality management plan in accordance with Sec 1001 and product compliance. Currently the American Concrete Pipe Association (ACPA), and National Precast Concrete Association (NPCA) are approved industry recognized audit programs with MoDOT. Approval of a producer quality management plan is the responsibility of Central Office Construction and Materials. Prior to allowing production under a producer quality management plan, the district must confirm that the producer’s certification is current and that it covers the material being produced. The district should audit the producer at least once a year and perform MoDOT Quality Assurance Testing on a quarterly basis while the produce is making products for MoDOT use. The district should perform additional auditing upon startup or when a problem arises. The district should perform MoDOT Quality Assurance Testing at the below recommended frequency:


Tested Property1Test Method MoDOT Quality Assurance
Air T152 Quarterly
Slump T119 Quarterly
Coarse Aggregate Deleterious TM 71 Quarterly
Coarse Aggregate Absorption T85 Quarterly
Compressive strength T22 Quarterly
Absorption (per mix) T280 Once a year
1 All samples shall be taken at the precast plant


Audits may include a review of all applicable paperwork, a review of the producer’s QC process, and an active inspection of current production. A record of each audit should be made in SiteManager using the 1052XXQCPA material code. The producer should notify the district in advance of their intended production schedule to allow MoDOT to schedule resources accordingly.

1052.2.3.1 Aggregate

Aggregate shall be concrete quality rock from an approved quarry and in accordance with Sec 1005. Max aggregate size is set by the wall system manufacturer for constructability and minimum cover requirements. Gradation limits found in Sec 1005 do not apply. Producer QC and QA aggregate sampling and testing shall occur as per Sec 1052.

MoDOT should audit the producer’s aggregate testing records as necessary. When a problem arises or when the producer testing records are in question, MoDOT’s audit should included sampling and testing of the aggregate.

1052.2.3.2 Cementitious

Cementitious material shall be in accordance with Sec 1017, Sec 1018 or Sec 1019 as appropriate. The producer is required to maintain a file of bills of lading or delivery receipts of cementitious material, showing the certification states required, which are to be readily available to the inspector.

MoDOT should audit the producer’s file of bills of lading when necessary. When a problem arises, MoDOT’s audit should include sampling and testing of the cementitious material. If a producer is using more than one brand of cementitious, the samples should be taken alternately to cover different brands.

1052.2.3.3 Concrete Mixture

The concrete should follow the requirements found in Sec 502 except where the wall system requirements are different. Prior to production, the producer should submit a mix design for approval. Any exposed concrete should be air entrained for freeze thaw durability reasons. The precast manufacturer is responsible for the mix design and proportioning with the restriction that a minimum of 470 pounds per cubic yard of cementitious material is required. Non-standard admixtures not covered by the Standard Specification may be used if approved. Approval of non-specification compliant admixtures requires the precast manufacturer to obtain and hold a letter from the admixture supplier stating the admixture will not cause an negative affects when combined the other specific components and processes used by the precast manufacturer.

MoDOT should audit the producer’s records to ensure the approved mix design was followed.

1052.2.3.4 Steel Reinforcement

Reinforcing steel for use in the manufacture of precast drainage units should be in accordance with Sec 1036 for PAL material. The material shall be reported by the producer using the PAL receiver form, GS-13 Form 2. The precast manufacturer shall retain certification and mill test reports for 3 years and make them available to the inspector when requested.

Any reinforcing steel or steel hardware used that serves a design function shall meet all of the applicable Buy America requirements.

The producer shall inspect all pieces for the correct amount and placement of reinforcing steel. A record of compliance should be kept by the producer in accordance with the producer quality management plan.

MoDOT should audit the producer’s steel reinforcement PAL records as necessary. When a problem arises or when the PAL records are in question, MoDOT’s audit should include sampling and testing of the reinforcing steel. MoDOT’s audit should also include visually checking PAL materials when possible for proper storage, handling, and labeling. MoDOT’s audit may also include checking steel reinforcement placement when necessary.

1052.2.3.5 Finished Pieces

The finished sections are to be examined by QC for conformance to dimensions, workmanship, and marking. Permissible variations in dimensions and rejection criteria for workmanship are specified in Sec 1052.

MoDOT’s audit may include checking finished pieces for conformance to project plans.

1052.2.3.6 Compressive Strength Test

During the production of panels and precast posts, the producer shall randomly sample the concrete in accordance with AASHTO R 60. Compressive strength samples shall be randomly selected for every production lot. A production lot will be defined as a group of panels and precast posts that will be represented by a single compressive strength sample, and shall consist of a single day’s production.

Field cured compressive strength samples shall be used as the basis of acceptance. QC shall make sufficient cylinders, in accordance with AASHTO T23, cured in the same manner as the panels and precast posts and tested for design strength compliance. Therefore, the cylinders shall be treated in the same manner as the panels. The average compressive strength of these cylinders, when tested in accordance with AASHTO T 22, shall represent the compressive strength of the production lot. When a compressive strength result falls below design strength, the engineer of record must evaluate and approve acceptance of non-conformance.

MoDOT should audit the producer’s QC/QA compressive strength testing records as necessary. When a problem arises or when the producer testing records are in question, MoDOT’s audit should include sampling and testing of the concrete.

1052.2.3.7 Placement of Concrete

The transporting and placing of concrete shall be by methods that will prevent the segregation of the concrete material and the displacement of the reinforcement steel from its proper position in the form.

1052.2.3.8 Curing

Precast panels and posts shall be cured by any one of the following methods, or combination of methods approved by the engineer that will give satisfactory results, or in accordance with panel manufacturer’s recommendations. The panels and posts shall be cured until design strength is met.

Steam Curing. Steam curing shall be in accordance with Sec 1029. Units may be placed in a curing chamber, free from outside drafts and cured in a moist atmosphere maintained by the injection of steam for such time and at such temperature as may be needed to enable the unit to meet the strength requirements. The curing chamber shall be so constructed as to allow full circulation of steam around the entire unit.

Water Curing. Precast drainage units may be water cured by covering with water-saturated material or by a system of perforated pipes, mechanical sprinklers, porous hose, or by any other approved method that will keep the unit moist during the specified curing period.

Curing Membrane. Curing membrane, in accordance with Sec 1055, may be applied to the back of panels only, if used the panels shall be left in the forms until the strength requirements are met. If panels are removed from the forms before design strength has been met another curing method shall be used. Curing membrane shall not be used on posts for soundwall systems, as it may cause discoloration.

1052.2.3.9 Tolerances

Wall system components should be produced within the tolerances specified by sec 1052 or the wall system manufacturer. In case of conflict, the wall system manufacturer’s tolerances prevail. Pieces outside these tolerances should result in a non-conformance report to ensure they do not pose structural, constructability, or aesthetic problems.

1052.2.3.10 Identification Marking

An unexposed face of each precast panel or post is to be clearly and permanently marked by the manufacturer, in accordance with Sec 1052, with the following:

(a) Date of manufacture
(b) Production lot number
(c) Panel/post type

1052.2.3.11 Documentation

Once a shipper’s form is received by the producing district, a MoDOT identification number will be assigned and the completed shipper’s form returned to the precast facility. A copy of the shipper’s form should also be emailed to the receiving district’s materials contact to be forwarded on to the appropriate project office.

  • The producing district materials staff will maintain an electronic records of QC documentation in the district’s general materials or similar quality documentation folder on the V:/Contract Information Archives directory.
  • The receiving district should enter a disposition remark once the certification on the bill of lading is received and documenting where the bill of lading/certification will be stored with the project.

1052.2.4 Small Block Wall System Procedure

The producing district is responsible for acceptance of small blocks. Acceptance of small blocks shall be on the producer’s adherence to their producer quality management plan in accordance with Sec 1001 and product compliance. Approval of a producer quality management plan is the responsibility of Central Office Construction and Materials. Prior to allowing production under a producer quality management plan, the district must confirm that the producer's certification is current and that it covers the material being produced. The district should audit the producer on a regular basis and should perform additional auditing upon startup or when a problem arises. Audits may include a review of all applicable paperwork, a review of the producer’s QC process, and an active inspection of current production. A record of each audit should be made in SiteManager using the 1052XXQCPA material code. The producer should notify the district in advance of their intended production schedule to allow MoDOT to schedule resources accordingly.

1052.2.4.1 Aggregate

Aggregate shall be concrete quality rock from an approved quarry and in accordance with Sec 1005. Max aggregate size is set by the wall system manufacturer for constructability and minimum cover requirements. Gradation limits found in Sec 1005 do not apply. Producer QC and QA aggregate sampling and testing shall occur as per Sec. 1052.

MoDOT should audit the producer’s aggregate testing records as necessary. When a problem arises or when the producer testing records are in question, MoDOT’s audit should include sampling and testing of the aggregates.

1052.2.4.2 Cementitious

Cementitious materials shall be in accordance with Sec 1017, Sec 1018 or Sec 1019 as appropriate. The producer should maintain a file of bills of lading or delivery receipts of cementitious materials, showing the certification statements required, which are to be readily available to the inspector.

MoDOT should audit the producer’s file of bills of lading when necessary. When a problem arises, MoDOT’s audit should include sampling and testing of the cementitious material. If a producer is using more than one brand of cementitious, the samples should be taken alternately to cover different brands.

1052.2.4.3 Concrete Mixture

Some small blocks are produced using a dry cast concrete mixture while others are traditional concrete. The concrete should follow the requirements found in Sec 501 when wet cast systems are used. When dry cast systems are used, the producers may override Sec 501 with the engineer’s approval. Prior to production, the producer should submit a mix design for approval. Any exposed concrete should be air entrained for freeze thaw durability reasons. Sec 1052 requires small block manufacturers to perform free-thaw testing of their blocks periodically. This freeze thaw testing is important to ensure that salt exposure does not degrade the block. Blocks produced by dry cast systems are often prone to freeze thaw damage. When the installation location of a block system is outside the salt spray zone, the Engineer may consider waiving the freeze-thaw durability requirements. Non-standard admixtures not covered by the standard specifications may be used if approved the engineer.

Modot should audit the producer’s records to ensure the approved mix design was followed.

1052.2.4.4 Steel Reinforcement

While most small blocks do not include any steel reinforcement, any Sec 1036 steel used or hardware used to complete the wall system should meet all of the applicable Buy America requirements. A record of compliance should be kept by the producer in accordance with the producer quality management plan and be available to the inspector upon requested.

MoDOT should audit the producer’s steel reinforcement records as necessary. When a problem arises or when the records are in question, MoDOT’s audit should include sampling and testing of the reinforcing steel. MoDOT’s audit should also include visually checking PAL materials when possible for proper storage, handling, and labeling. MoDOT’s audit may also include checking steel reinforcement placement when necessary.

1052.2.4.5 Finished pieces

The finished sections are to be examined by QC for conformance to dimensions, workmanship, and marking. Permissible variations in dimensions and rejection criteria for workmanship are specified in Sec 1052.

MoDOT’s audit may include checking finished pieces for conformance to project plans.

1052.2.4.6 Compressive Strength Test

During the production of small blocks, the producer shall randomly sample the concrete in accordance with ASTM C140. Compressive strength samples shall be randomly selected for every production lot. A production lot will be defined as a group of small blocks that shall consist of a single day’s production or a maximum of 5000 blocks.

Field cured compressive strength samples shall be used as the basis of acceptance. For dry cast systems QC will pick random small blocks for compressive strength testing. For wet cast systems QC shall make sufficient cylinders that are cured in the same manner as the small blocks and tested for design strength compliance. Therefore, the cylinders shall be treated in the same manner as the panels. The average compressive strength of these cylinders, when tested in accordance with AASHTO T 22, shall represent the compressive strength of the production lot. When a compressive strength result falls below design strength, the engineer of record must evaluate and approve acceptance of non-conformance.

MoDOT should audit the producer’s QC/QA compressive strength testing records as necessary. When a problem arises or when the producer testing records are in question, MoDOT’s audit should include sampling and testing of the concrete.

1052.2.4.7 Placement of Concrete

The transporting and placing of concrete shall be by methods that will prevent the segregation of the concrete material.

1052.2.4.8 Curing

Precast small blocks shall be cured by any one of the following methods, or combination of methods approved by the engineer that will give satisfactory results, or in accordance with panel manufacturer’s recommendations. The small blocks shall be cured until design strength is met.

Steam Curing. Steam curing shall be in accordance with Sec 1029. Units may be placed in a curing chamber, free from outside drafts and cured in a moist atmosphere maintained by the injection of steam for such time and at such temperature as may be needed to enable the small block to meet the strength requirements. The curing chamber shall be so constructed as to allow full circulation of steam around the entire unit.

Water Curing. Precast drainage units may be water cured by covering with water-saturated material or by a system of perforated pipes, mechanical sprinklers, porous hose, or by any other approved method that will keep the unit moist during the specified curing period.

Curing Membrane. Curing membrane, in accordance with Sec 1055, may be applied to the back of panels only, if used the small blocks shall be left in the forms until the strength requirements are met. If small blocks are removed from the forms before design strength has been met another curing method shall be used. Curing membrane shall not be used on posts for soundwall systems, as it may cause discoloration.

1052.2.4.9 Tolerances

Small blocks should be produced within the tolerances specified by Sec 1052 or the wall system manufacturer. In case of conflict, the wall system manufacturer’s tolerances prevail. Pieces outside these tolerances should result in a non-conformance report to ensure they do not pose structural, constructability, or aesthetic problems.

1052.2.4.10 Identification Marking

Small blocks have no marking requirements.

1052.3 Special Designs and Shop Drawings

All wall systems should be from the bridge approved products list. For structural walls, individual projects will have a unique shop drawing showing how to build the wall from the approved system. Deviations from the approved shop drawings should not be allowed.

1052.4 Report

The producer will notify the producing district of completed units prior to shipping and the district will report these units as a SiteManager sample record. The producing district will issue the sample ID # to the producer upon notification and it may be used to indicate acceptance of that wall product. The producer will indelibly mark the product with the Sample ID number on an unexposed face of the panels and posts or will provide to the jobsite sufficient records to track individual pieces to the sample ID #s issued.

Any additional audits or inspection of components should also be reported in SiteManager. Issues or comments from the field should be added to the initial sample record by either unauthorizing it or by using a disposition remark.

The following information is to be included within the SiteManager ID, in addition to that normally required for a sample record:

(a) Project Number and MSE or Sound Wall Number.
(b) Panel type and number of panels of each type.
(c) Date of production.
(d) Square footage of each type.

Personal tools