3238Precast Concrete Box Culverts

3238.1SCOPE

Provide products manufactured in a precast concrete manufacturing plant pre -approved by the Materials Engineer, listed on the APL and meeting the requirements of 3240, “Precast Concrete Manufacturing.” Provide precast concrete single and multi-cell box Culverts sections, headwalls, and aprons, including box Culvert sections used in the as-cast position as manholes or manhole-type Structures.

3238.2REQUIREMENTS

A Fabrication Drawings, Falsework, and Forms If full construction details are not included in the Plans, provide shop drawings according to 3240, “Precast Concrete Manufacturing,” before fabricating the units. Provide shop drawings and design calculations for mitered Culvert bends and other specialty Culvert shapes. Provide precast concrete box Culverts with individual sections at least 4 feet long capable of being tied to the adjacent section with concrete pipe ties as specified by Standard Plate 3145 and as shown on the Plans. Unless specifically called for in the Plans, openings in the flow line or sidewalls are not allowed. B Materials Provide concrete with mix designations as shown on the Plans for the specific items of Work. C Forms Provide forms capable of withstanding pressure from concrete, vibration, and impact without distorting. Set and maintain forms in a mortar tight condition, free of warp, and on a rigid foundation. Provide joints in the sectional forms without offset. Set forms to create dimensions of the precast unit as shown on the Plans. Repair or replace forms not meeting the dimensions shown on the Plans before casting additional sections. When recesses around lifting devices are required, use forming devices

provided by the lifting device manufacturer. Clean forms before use. Treat the face of the forms in contact with the concrete with form coating Material in accordance with 3902, “Form Coating Material,” before setting the forms. D Lifting Devices and Other Steel Inserts When lifting devices or other steel inserts will have less than 1.5 inches of concrete cover in the finished Structure or if the recess is to be grouted in the field, provide items that are galvanized according to 3392, “Galvanized Hardware.” E Reinforcement Steel Place reinforcement steel as shown on the Plans. Support reinforcement steel with chairs. Splice, secure, and tie reinforcement steel in accordance with 2472, “Metal Reinforcement.” Provide concrete cover of at least 1.5 inches or as shown on the Plans. Provide stainless steel, plastic, plastic tipped, hot dipped galvanized, or mechanically galvanized reinforcement supports in contact with the forms. Extend coatings on the supports at least 1 inch from the form surface. Do not tack-weld reinforcement. Lap wire mesh as detailed in the Plans. Cut wire mesh so that the sum of the 2 end overhangs equals no more than 1 transverse wire spacing. When measuring the length of wire mesh for compliance with Plans (splice lengths, etc.) the end overhang shall not exceed 1/2 of the transverse wire spacing. When a secondary pour will be used for adding a weir wall, an integral base for a manhole or similar Structures, use epoxy-coated steel reinforcement across the joint, with the bars being cast in the first pour or set in epoxy-filled drilled holes. F Placement of Concrete Do not place concrete for precast units until the Materials Engineer inspects and approves the forms and steel placement. Place the concrete in each precast unit without interruption. Vibrate the concrete internally, externally, or both, to produce uniformly dense concrete and to avoid displacement of enclosures or steel units. Internally vibrate in accordance with 2401.3D, “Compaction of Concrete,” except provide internal vibrators with a vibrating head no greater than 1 1/4 inch in diameter and capable of operating at a frequency of at least 100 hertz. G Concrete Curing Cure according to the requirements of 3240, “Precast Concrete Manufacturing,” until the concrete reaches a compressive strength of at least 2,500 psi based on compressive strength test results from control cylinders cured with the product. H Concrete Finishing and Repair Provide formed surfaces of the precast units with a uniform dense surface finish in accordance with 2401.3F.2.a, “Ordinary Surface Finish.” After removing the forms, examine the concrete surfaces for areas of unsound concrete and defective surfaces caused by faulty forms or form assembly, improper concrete placement, improper form removal, and other causes. Remove and replace concrete with porosity, honeycomb, delamination, hollow sound, or segregated Materials as approved by the Materials Engineer. The Materials Engineer will not allow the following repairs in the finished product:

With the approval of the Materials Engineer and in compliance with the plant Q uality Control program, the Contractor may repair minor surface cavities or irregularities before the unit completes curing. I Certified Plant Requirement Provide precast concrete box culverts, end sections, and appurtenances constructed in a precast concrete fabrication plant certified by the American Concrete Pipe Association, the National Precast Concrete Association, or another organization approved by the Materials Engineer. If requested, provide quality control and plant certification records to the Materials Engineer. J Tolerances Dimensional tolerances will be based on AASHTO M 259 Standard Specification for Precast Reinforced Concrete Box Sections for Culverts, Storm Drains, and Sewers.

3238.3SAMPLING AND TESTING

The Materials Engineer will inspect the units at the plant and will stamp approved units with the official mark of the Department. Store individual units in an upright position to facilitate inspection, unless otherwise approved by the Materials Engineer. Do not ship units without the official mark of the Department. Notify the Materials Engineer at least one full Business Day before intent to ship. Complete finishing and repair Work on units before submitting notice of intent to ship. The units are subject to final inspection of the units after delivery. Unless otherwise directed by the Materials Engineer, mark the inside of each box section with the following information: