Category:1049 Precast Concrete Box Culverts
This article establishes procedures for inspecting, acceptance and reporting of precast concrete box culverts for post-7/1/2004 contracts. Refer to Sec 1049 for MoDOT’s specifications.
For Laboratory testing and sample reporting procedures, refer to EPG 1049.4 Laboratory Testing Guidelines for Sec 1049.
Design and acceptance of these structures are covered by ASTM C 1577 in addition to the plans and specifications. Any deviation from the plans or the AASHTO designs must be approved as a special design.
Acceptance of precast concrete box culverts may be on the basis of an approved, industry recognized QC program, inspection by MoDOT, or a combination of the two methods, at the discretion of the district. Approval of QC programs is the responsibility of Central Office. Currently the QC programs of the American Concrete Pipe Association (ACPA) and the National Precast Concrete Association (NPCA) are approved. Prior to allowing production under a QC program, the district must confirm that the producer's certification is current and that it covers the material being produced. The district must initially, and on a recurring basis, confirm that the producer routinely and diligently follows the requirements of the QC program, and that material produced for MoDOT is specification compliant. This confirmation will be in the form of a quality assurance visit, including a review of all applicable paperwork, a review of the producer’s QC process, and an active inspection of current production (an AASHTOWARE Project (AWP) plant inspection record is required - 1049XXQCP). When a producer is allowed by the district to produce under a QC program, the producer must agree to notify the district in advance of their intended production schedule. Acceptance of precast concrete box culverts, with MoDOT inspection, is to be based on the inspection of materials being incorporated into the sections, inspection of both the dimensions and the placement of forms and reinforcement, results of compressive tests on cured concrete cylinders or cores, and inspection of the finished pieces.
|Current General Services Specifications (MGS) By Subject|
(a) Rule with suitable graduations to accurately measure the material to be inspected.
(b) OK - MoDOT stamp.
(c) Weather-resistant marking materials.
(d) Applicable AASHTO specifications.
Inspection and reporting of coarse aggregate, fine aggregate, cement, fly ash shall be as appropriate for those materials.
Prior to concrete being poured, confirm the amount and placement of reinforcement. The amount and placement of welded wire fabric is to be as specified in ASTM C 1577 as applicable.
Compressive tests may be made on either concrete cylinders or cores drilled from the wall of the sections at the option of the manufacturer. If the manufacturer chooses to take cylinders and they fail, the manufacturer then has the option to core sections for possible acceptance.
Cylinders must be made in accordance with AASHTO T 280 and must be capped.
Acceptance cylinders are the responsibility of the manufacturer. An inspector’s job is to review the results for adequacy. It is good procedure to randomly validate the manufacturer results by making cylinders for comparison.
Cores in accordance with AASHTO T 280 must be both capped and lime cured.
The finished sections are to be examined for conformance to dimensions, workmanship and marking. All permissible variations are specified in ASTM C 1577.
Each section shall be marked as follows by the manufacturer by indenting into the concrete or with waterproof paint:
(a) Box section span, rise, table number, design earth cover and specification designation.
(b) Date of manufacture.
(c) Name or trademark of the manufacturer.
(d) Each section shall be clearly marked by indentation on either the inner or outer surface during the process of manufacturer so that the location of the top will be evident immediately after the forms are stripped. In addition, the word "top" shall be lettered with waterproof paint on the inside top surface.
(e) If the manufacturer is allowed to produce under an approved QC program, each section considered by the manufacturer to be specification compliant will be marked by the manufacturer with the indicator required by the QC program. Sections rejected by the manufacturer may be marked or handled in accordance with the QC program but the rejection must be clearly indicated.
(f) If the manufacturer is allowed to produce under an approved QC program, each section to be shipped will be marked by the manufacturer with the Sample ID number provided by the district. If the producer has marked a piece with a Sample ID number, and the section is found to be unacceptable during an audit, the Sample ID number must be neatly obliterated.
Sections accepted by MoDOT inspection are to be marked with "OK-MoDOT" by the inspector. Rejected sections are to be marked with a single vertical mark, near the manufacturers marking and shall be made with weather resistant marking material.
Any modification of a unit, other than constructing a box unit exactly as described in the specifications, is considered a special design, including any pipe cutouts or drainage holes to be made in the unit for any reason, whether prior to, during, or after final placement on site. Any special or modified designs submitted for approval must have been reviewed and sealed by a professional engineer, registered in Missouri, and representing the contractor or producer. Requirements for submitting special or modified designs are described in Sec 1049. Approval of a special design for one job does not constitute approval for any other job.
Submittal of special designs is discussed further in EPG 106.16 Special Designs. Special and modified design units, at the discretion of the district, may not be accepted under a QC program.
If reinforcing bars are proposed in lieu of the welded wire fabric listed in AASHTO, it is considered to be a special design.
If end sections are proposed to be constructed other than by the MoDOT Standard Plans for cast-in-place culverts, it is considered to be a special design. Calculations and other proof of equal or better design must be submitted with the request.
Units inspected and accepted by a QC program must be reported to the district prior to shipment. Shipment information will be recorded in AWP by the district. The district will provide the producer with the Sample ID number(s) for the product. A single Sample ID may represent multiple sections, as may be indicated in the Sample Record. The producer will place the Sample ID number on the product indelibly.
For units produced with MoDOT inspection; materials used in the manufacture of these sections should be reported as applicable and the inspector should check PAL materials visually and for correct paperwork, if possible. The plant inspector located at the concrete proportioning plant shall create an AWP sample record for each day's pour documenting the class of concrete poured and the units manufactured from that pour. The name of the manufacturer must be shown.
Finished sections shall be reported through AWP. The following information is to be included on the free form template, in addition to that normally required for a sample record:
(a) Quantity: Length of box culvert, in feet or meters.
(b) Date of production.
(c) AASHTO Designation or Special Design Approved (Date).
(d) Design earth cover height.
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