Beiswenger - Structural - Laserfiche WebLink

Home Browse Search

SUBARTICLE 346-7.6 (Page 331) is deleted and the following substituted: 346-7.6 Transit Time: Ensure compliance with the following maximum allowable time between the initial introduction of water into the mix and depositing the concrete in place: TABLE 6 Non-Agitator Trucks Agitator Trucks 45 minutes 60 minutes 75 minutes* 90 minutes* .When a water-reducing and retarding admixture (Type D, Type G or Type II) is used. SUBARTICLE 346-7.7 (Page 331) is deleted and the following substituted: 346-7.7 Adding Water to Concrete at the Placement Site: Perform an initial slump test before the addition of water at thejobsite. If the slump, as delivered, is outside the tolerance range, reject the load. If the slump is within the tolerance range, that load may be adjusted by adding water provided the addition of water does not exceed the water to cementitious materials ratio as defined by the mix design. After adjusting the slump, perform a slump test to confirm the concrete is within the slump tolerance range. Perform a slump test on the next load to ensure the concrete is within the slump tolerance range. Do not place concrete represented by slump test results outside of the tolerance range. ARTICLE 346-8 (Page 331) is deleted and the following substituted: 346-8 Plastic Concrete Sampling and Testing. QC tests include air content, temperature, slump, and preparing compressive strength cylinders for testing at later dates. In addition, calculate the water to cementitious materials ratio in accordance with FM 5-501 for compliance to the approved mix design. Ensure that each truck has a valid mixer identification card issued by the Department, the revolution counter on the mixer is working properly, and calibration of the water dispenser has been performed within the last twelve months and verify batch weights within required limits of the mix design. Reject any concrete batches that are delivered in trucks that do not have mixer identification cards. The Contractor may remove the mixer identification cards when a truck mixer is discovered to be in noncompliance. When the mixer identification card is removed for noncompliance, forward the card to the District Materials Engineer in the District where the plant is located. Perform plastic concrete tests on the initial delivery of each concrete design mix each day. Ensure QC technicians meeting the requirements of Section 105 are present and performing tests throughout the placement operation. Ensure one technician is present and performing tests throughout the placement operation at each placement site. If a placement site has multiple concrete trucks, identify the number of technicians in the Quality Control Plan. Ifa placement site has multiple trucks placing concrete, then have at least two technicians present at that site. Ensure that the equipment used for delivery, placement and finishing meets the requirements of this Specification. Do not proceed with the placement operation until QC tests confirm that the delivered concrete complies with the plastic properties specified. When a truck designated for