(5) Concrete Finish and Tolerances. Concrete surface for the front face shall be ordinary surface finish unless otherwise shown on the plans and for the rear face an unformed surface finish. Rear face of the panel shall be roughly screeded to eliminate open pockets of aggregate and surface distortions in excess of 1⁄4-inch. (6) Tolerances. All units shall be manufactured within the following tolerances: All dimensions within 16-inch. Angular distortion with regard to the height of the panel shall not exceed 0.2-inch in 5 feet. (7) Compressive Strength-Acceptance of the concrete face panels with respect to compressive strength will be determined on a lot basis. The lot will consist of all production units (batches of concrete or panels) produced within a week's or 7-day production operation. Production units shall be randomly selected in accordance with the production day sample sizes of Table A and tested for compressive strength. Compression tests shall be made on standard 6-inch by 12-inch test specimen prepared in accordance with AASHTO T-23 or cores obtained and prepared in accordance with AASHTO T-24. Compressive strength testing shall be conducted in accordance with AASHTO T-22. When standard 6-inch by 12-inch test specimens are utilized a minimum of four cylinders shall be cast for each production unit sampled. Two of these specimens shall be cured in the same manner as the panels and tested at 7-days. The remaining two cylinders shall be cured in accordance with AASHTO T-23 and tested at 28-days. The test value of each two cylinder group will be their average compressive strength. Acceptance of the lot will be made if all acceptance tests in a lot are greater than 4,500 psi or provided no individual 28-day compressive strength test result falls below 4,000 psi and the average 28-day compressive strength of all test results for the lot equals or exceeds the acceptance limits set forth in Table B. The acceptance limits of Table B shall also apply to core compressive strength test results. *(Range) The difference between the largest and smallest acceptance test result. The early strength determination procedures of FHWA Rapid Test Procedure RT-6 may be used in lieu of the standard 28-day compressive strength test procedures upon approval by the engineer. (8) Rejection. Units shall be subject to rejection because of failure to meet any of the requirements specified above. In addition any or all of the following defects shall be sufficient cause for rejection: a. Defects that indicate imperfect moulding. b. Defects indicating honeycombed or open texture concrete. (9) Marking. The date of manufacture shall be clearly scribed on the rear face of each panel. (10) Handling, Storage and Shipping. All units shall be handled, stored, and shipped in such manner as to eliminate the danger of chipping, cracks, fractures and excessive bending stresses. Panels in storage shall be supported on firm blocking located immediately adjacent to tie strips to avoid bending the tie strips. (11) Concrete Footing. Concrete shall conform to Section 602. (b) Steel Face Panels. Steel face panels shall be fabricated of cold rolled galvanized steel and conform to the plans and the minimum requirements of ASTM A446, Grade C or other approved material. The steel face panels shall be galvanized to conform to the minimum requirements of ASTM A525, Coating Class G 90. (c) Reinforcing and Tie Strips. Tie strips shall be shop fabricated of hot rolled steel conforming to the minimum requirements of ASTM A-570, Grade C or equivalent. They shall be hot dip galvanized to conform to minimum requirements of ASTM A-123. Reinforcing strips shall be hot rolled from bars to the required shape and dimensions. Their physical and mechanical properties shall conform to ASTM A-36 or equivalent. They shall be hot dipped galvanized to conform to the minimum requirements of ASTM A123. They shall be cut to length and tolerances shown on the plans. Holes for bolts shall be punched in the locations shown. All reinforcing and tie strips shall be carefully inspected to insure they are true to size and free from defects that may impair their strength and durability. (d) Fasteners. Bolts and nuts shall be hexagonal cap screw, high strength conforming to ASTM A-325 or equivalent galvanized. They shall be 1⁄2 inch in diameter, 11⁄4 inch in length with 4 inch thread length. (e) Joint Filler. (For use with concrete face panels.) (1) Filler for vertical joints between panels shall be flexible open cell polyether foam strips. (2) Filler for horizontal joints between panels shall be resin-bonded cork filler conforming to ASTM D 1752 (Type II) or equal as approved by the Engineer. Joint Covers. (For use with steel face panels.) Joint covers shall be fabricated of cold rolled galvanized steel and conform to the plans and the minimum requirements of ASTM A446, Grade C. Joint covers shall be galvanized to conform to the minimum requirements of ASTM A 525, Coating Class G-90. (g) Select Granular Backfill Material. All backfill material used in the structure volume shall be reasonably free from organic or otherwise deleterious materials and shall conform to the following gradation limits as determined by AASHTO T-27: Materials not meeting the above limits may be used with the written consent of the Engineer. Such materials must be tested for their functional properties to assure that they are consistent with the parameters used in the design calculations. (h) General. The Contractor, or the supplier as his agent, shall furnish the Engineer a Certificate of Compliance certifying the above materials comply with the applicable contract specifications. A copy of all test results performed by the Contractor or his supplier necessary to assure contract compliance shall also be furnished the Engineer. Acceptance will be based on the Certificate of Compliance, accompanying test reports, and visual inspection by the Engineer. Construction Requirements 613.03 Wall Excavation. Unclassified excavation shall be in accordance with the requirements of Section 203 and in reasonably close conformity to the limits and construction stages shown on the plans. 613.04 Foundation Preparation. The foundation for the structure shall be graded level for a width equal to or exceeding the length of reinforcing strips or as shown on the plans. Prior to wall construction, except where constructed on rock, the foundation shall be compacted with a smooth wheel vibratory roller. (a) When concrete face panels are specified, at each panel foundation level, an unreinforced concrete leveling footing shall be provided as shown on the plans. The footing shall be cured a minimum of 12 hours before placement of wall panels. 613.05 Wall Erection. (a) Concrete face panels. Precast concrete panels shall be aligned vertically using inserts cast into the top edge of panels. Panels should be placed in successive horizontal lifts in the sequence shown on the plans as backfill placement proceeds. As fill material is placed behind a panel, the panels should be maintained in vertical position by means of clamps placed at the junction of adjacent panels and temporary wooden wedges placed in the horizontal joint at the junction of the two adjacent panels on the external side of the wall. External bracing may also be required for the initial lift. Vertical tolerances (plumbness) and horizontal alignment tolerance shall not exceed 3/4 inch when measured along a 10-foot straight edge. The maximum allowable offset in any panel joint shall be 3/4 inch. The overall vertical tolerance of the wall (plumbness from top to bottom) shall not exceed 1/2 inch per 10-feet of wall height. (b) Steel face panels. Skin elements are placed by hand in successive horizontal lifts as indicated on the plans. Backfill must be maintained no more than two skin elements below top of wall. Wooden wedges shall be placed at not more than 5-foot centers between the skins on the exposed face to maintain verticality during backfilling. Batter boards shall be used to maintain verticality for the first five lifts. All wedges shall be removed as backfilling proceeds. A minimum of five lifts shall be supported by wedges at all times. 613.06 Backfill Placement. Backfill placement shall closely follow the erection of each lift of panels. At each reinforcing strip level, backfill should be roughly leveled before placing and bolting strips. As shown on the plans, reinforcing strips shall be placed normal to the face of the wall. The maximum lift thickness shall not exceed 10 inches (loose) and shall closely follow panel erection. The Contractor shall decrease this lift thickness if necessary to obtain the specified density. At the end of each day's operations, the Contractor shall shape the last level of backfill as to permit runoff of rainwater away from the wall face. Backfill shall be compacted in accordance with the project specifications for embankment except that the minimum required compaction shall be 95% of maximum density as determined by AASHTO T-99 and that the moisture content shall be plus or minus 2 percentage points of the optimum moisture content as determined by AASHTO T-99. Backfill compaction shall be accomplished without disturbance or distortion of reinforcing strips and panels, compaction in a strip 3 foot wide adjacent to the backside of the wall shall be achieved using light mechanical tampers. Method of Measurement 613.07 (a) Concrete face panels-The unit of measurement for furnishing and fabricating all materials for the walls, including concrete face panels, reinforcing and tie strips, fasteners, joint filler, and incidentals, will be the square foot. (b) Steel face panels-The unit of measurement for furnishing and fabricating all materials for the walls, including the steel face panels, reinforcing strips, fasteners, joint covers and incidentals, will be the square foot. (c) The unit of measurement for wall erection will be the square foot. The quantity to be paid for will be the actual quantity erected in place at the site. Payment shall include compensation for all labor and materials required to prepare the wall foundation, put in place the reinforcing strips, and erect the panel elements to the lines and grade shown on the plans. (d) The unit of measurement for the concrete footing will be the number of linear feet, complete in place and accepted, measured along the line and grade of the footing. For calculation purposes, each full size concrete face panel is equivalent to 24.2 square feet. (e) Backfill-The unit of measurement for select granular backfill will be the embankment plan quantity cubic yards in accordance with subsection 109.02. Basis of Payment 613.08 The quantities, determined as provided above, will be paid for at the contract price per unit of measurement, respectively, for each pay item listed below and shown in the bid schedule, which prices and payment will be full compensation for the work prescribed in this section, except as provided in (a), (b), below: (a) Excavation will be measured and paid for as provided in Section 203. (b) Water will be measured and paid for as provided in Section 207. 614.01 This item shall consist of damp-proofing concrete or masonry surfaces with tar or asphalt, as called for, in reasonably close conformity with these specifications and at the locations shown on the plans or ordered by the Engineer. Materials 614.02 Materials shall conform to the requirements specified in the following subsections: Primer... 702.06(a) or (b) as applicable Construction Requirements 614.03 After the concrete is cured in conformity with the requirements given in Section 552, the surfaces to be damp-proofed shall be allowed to dry at least 10 days. They shall then be coated thoroughly with four coats of primer applied cold with a brush or spray gun and each coat shall be absorbed before the succeeding one is applied. After absorption of the fourth coat, a seal coat shall be heated if necessary and applied at a temperature compatible with the type of material and brushed or sprayed thoroughly into all surfaces. The seal coat shall have hardened before any water or earth is allowed to come against it. No coat shall be applied when the concrete or the preceding coat is damp, or at any time when the weather is unsuitable. Method of Measurement 614.04 The quantity to be paid for will be the actual number of square yards of surface damp-proofed, completed, and accepted. If a lump-sum payment is to be made, measurement will be in accordance with subsection 109.02. Basis of Payment 614.05 The quantity, determined as provided above, will be paid for at the contract price per unit of measurement for the pay item listed below that is shown in the bid schedule, which price and payment will be full compensation for the work prescribed in this section. 615.01 This item shall consist of the waterproofing of concrete surfaces in reasonably close conformity with these specifications, by the method designated in the bid schedule, and at the locations shown on the plans or ordered by the Engineer. Materials 615.02 Materials shall conform to the requirements specified in the following subsections: 615.03 Membrane Waterproofing. Membrane waterproofing shall be a firmly bonded membrane composed of two layers of asphalt-treated fabric and three moppings of asphalt or two layers of tar-treated fabric and three moppings of tar, together with a coating of primer, all applied as follows: All concrete surfaces which are to be waterproofed shall be smooth and shall be free of projections or depressions that might cause puncture of the membrane. |