2011-226B.1 - Laserfiche WebLink

Home Browse Search

Minimum Time for Form Minimum (%) of 28 -day Location of Concrete Placement Removal for any Strength Compressive Strength for Concrete * Form Removal 2) Walls , piers , columns , sides of beams 24 hours * * * * * * 50 and other vertical surfaces 3 ) Front face form of curbs 6 hours 70 * For mass concrete, remove forms in accordance with 346-3 . 3 * * Reference 400- 16.4 * * * e section until 70% of the specified 28 -day concrete strength is attained. Also , refer to Do not pace additional load on th 00-7 .4 . When using the percent of required strength, cast test cylinders for each mix for compressive strength determination or develop a curing concrete strength versus time curve (S/T Curve) which can be used in lieu of multiple test cylinders to determine when percent of required strength has been met . Prior to curve use ; obtain the Engineer ' s approval of the S/T Curve and its supporting data . An approved testing laboratory may be used to provide this information with approval of the Engineer. Plot S/T Curves using at least three different elapsed times that begin once test cylinders are cast; however, one of the elapsed times must be prior to the Contractor ' s intended form removal . Each elapsed time plotted must have a corresponding compressive strength computed by averaging the compressive strength of two test cylinders . Cure such test cylinders as nearly as practical in the same manner as the concrete in the corresponding structural component, and test them in accordance with ASTM C 39 and ASTM C 31 . Perform cylinder casting, curing, and testing at no expense to the Department and under the observation of the Engineer. When the S/T Curve indicates a compressive strength equal to or greater than the percentage of specified strength shown in the table above for form removal , the Contractor may remove the forms . When the ambient air temperature falls 15 °F or more below the ambient air temperature that existed during development of a S/T Curve, use a S/T Curve that corresponds to the lower temperature and that is developed in accordance with this section . Do not remove forms at any time without the consent of the Engineer. Even when the Engineer provides consent to remove the forms , the Contractor is responsible for the work. SUBARTICLE 400- 15 . 2 . 5 . 1 (page 397) is deleted and the following substituted : 40045 . 2 . 5 . 1 General : Apply a Class 4 finish on bridge decks and concrete approach slabs . On Short Bridges (bridges having a length less than or equal to 100 ft) , and on Miscellaneous Bridges (Pedestrian, Trail and Movable Spans) regardless of length, meet the finish and smoothness requirements of 400 - 15 . 2 . 5 . 2 and 400 - 15 . 2 . 5 . 4 . On Long Bridges (bridges having a length greater than 100 ft) meet the finish and smoothness requirements of 400 - 15 . 2 . 5 . 3 and 400- 15 . 2 . 5 . 5 . When an existing bridge deck is widened, see the plans for the finish and smoothness requirements of the existing bridge deck and its new widened section . After meeting the screeding requirements of 400 - 7 . 13 and curing requirements of 400 - 16 and the smoothness requirements , herein, groove the bridge deck and approach slabs . Regardless of bridge length, finish decks with less than 2 1 /2 inches of top cover in accordance with the requirements for Short Bridges . - 137 - FPID ( S ) : 4231864 - 58 - 01