a maximum corrosion rate as follows if tested in accordance with ASTM G59.
901.10Components of MSE Retaining Walls
Precast concrete face panels shall be produced from a source listed on the QPL of Certified Precast Concrete Producers, in accordance with ITM 813. Concrete shall 590 have a compressive strength equal to or greater than 4,000 psi at 28 days. The target water/cementitious ratio for the concrete mix design shall not exceed 0.435. The cement content and target water/cementitious ratio of the concrete mix design shall be sufficient to obtain the specified minimum 28-day compressive strength. Air-entraining admixture and chemical admixture types A, B, C, D, or E from the QPL of PCC Admixtures and Admixture Systems may be used. Ground-reinforcement connection hardwa re and reinforcing bar lifting devices shall be set in place and secured prior to beginning casting, in accordance with the 600 dimensions and tolerances shown on the working drawings.
based on a lot of 50 panels, or fraction thereof, for each day’s production. Sampling and testing of the plastic concrete shall be in accordance with 505.01, or the ASTM equivalent. A minimum of one water/cementitious ratio, slump, air content, and relative yield tests shall be run per production lot, per day. A minimum of two 6 in. by 12 in. cylinders shall be cast per day’s production lot for compressive strength 610 determination. Cylinders shall be cured in the same manner as the panels they represent. Relative yield, air content, and sl ump of the concrete shall be in accordance with 702.05. Compressive strength shall be determined in accordance with AASHTO T 22 or ASTM C39, with lot acceptance based on the average of 2 cylinders tested at an age no greater than 28 days. Panels shall not be shipped until the compressive strength meets or exceeds the 28-day requirement. If the cylinder-test results do not satisfy the requirements described herein, and additional cylinders for testing are not availa ble, the manufacturer may core the panels. The wall manufacturer shall randomly select two panels from the lot for coring in 620 accordance with AASHTO T 24 or ASTM C42. The wall manufacturer shall obtain one core on the backside of each panel w ith a device that produces uniform test 901.10 982 samples without coring completely through the panel. Coring shall not be located within 6 in. of the panel fasteners or the e dges of the panels and shall avoid the panel's reinforcing steel. The wall manufacturer shall fill the core holes with equivalent concrete materials or rapid setting patch materials, and trowel to produce a smooth finish. Excess material removed during troweling shall not be reused. If rapid setting patch material is used, mixing and curing shall be in accordance with the manufacturer's recommendations. Compressive strength testing shall be performed on the cores. If the average st rength-test results from the cores satisfy or exceed the 630 requirements described herein, the pr oduction lot panels may be shipped. b . C a s t i n g The panels shall be cast on a flat area, wi th the front face of the form at the bottom, and the back face at the upper part. Tie strip guides shall be set on the rear face. The concrete in each unit shall be placed without interruption and shall be consolidated as necessary to prevent the formation of segreg ation or cleavage planes. Clear form oil from one manufacturer shall be used throughout the casting operation. c. Curing 640 The panels shall be cured for a sufficient length of time such that the concrete develops the specified compressive strength.
unit.
The concrete surface for the front panel face shall have a surface finish produced from contact with the form. The rear face of the panel shall be sc reeded to eliminate 650 open pockets of aggregate and surface distortions in excess of 1/4 in. f. Tolerances All panels shall be manufactured within the tolerances as follows:
Squareness, as determined by the difference between the two diagonals, shall not exceed 1/2 in. (3) Panel-Surface Finish Surface defects on smooth formed surfaces measured on a length of 5 ft shall not exceed 1/8 in. Surface defects on textured fi nished surfaces measured on a length of 5 ft shall not exceed 5/16 in. 901.10 983 g. Compressive Strength Verification Verification of panel compressive strength will be conducted by the Engineer. 670 The frequency of verification testing will be one test for every 750 panels per manufacturer with a minimum of one test per contract. One panel will be randomly selected and two locations will be selected for coring. In the presence of the Engineer, the Contractor shall obtain two 4 in. cores on the backside of the panel without coring completely through the panel. The Contract or shall refill the core holes with rapid setting patch materials and trowel to produce a smooth finish. Excess material removed during troweling shall not be reused. Mixing and curing of the patching materials shall be in accordance with the manufacturer’s recommendations. The Engineer will test the cores in accordance with AASHTO T 24. The 680 verification test results will be averaged a nd shall be in accordance with 901.10(a)1a. If the initial verification test results do not satisfy the requirements described herein, the Engineer will randomly select two different panels for additional verification testing. If the additional verification tests satisfy the requirements described herein, no further action is required. If the test results still do not satisfy the requirements described herein, installation of panels sh all cease and the Engineer will conduct an investigation. Panels manufactured on th e same dates as the panels cored for verification tests that have already been in stalled will be considered and adjudicated as failed material in accordance with 105.03. The Engineer will conduct verification testing until three consecutive dates of production satisfy the strength requirements 690 described herein. The Contractor or wall manufacturer shall make arrangements so panels from three consecutive dates of production are accessible for coring. Installation of panels may resume once acceptable verification testing results are achieved.
Units will be subject to rejection due to their failure to be in accordance with the requirements as specified herein. The following defects may result in rejection:
concrete.
such as broken or chipped concrete, or color variations or dunnage marks on the front face due to excessive form oil or other reasons.
The Engineer will determine whether spalled, honeycombed, chipped, or 710 otherwise defective concrete shall be repaired or be cause for rejection. Repair of concrete, if allowed, shall be completed in a manner which is acceptable to the Engineer. Repair to concrete surfaces that are to be exposed to view after completion of construction shall be subject to approval. 901.10 984
The place and date of manufacture, and production lot number shall be shown on the rear face of each panel. 720
supported on blocking located immediately adjacent to tie strips to avoid bending the tie strips. 2. Coping The coping may be precast or cast-in-place.
The horizontal and vertical joint spacers shall include compression blocks, pins, or other manufacturer’s recommended materials to provide a uniform joint. The joint cover shall be either a non-woven needle-punch polyester geotextile or a woven monofilament polypropylene. The joint cover shall be attached to the rear face of the panels with a manufacturer’s recommended adhesive. A letter certifying that th e joint spacers and joint cover adhesive material supplied is in accordance with the manufacturer’s r ecommendations shall be provided prior to use of the materials. 740