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(A) Place concrete in accordance with ACI 301, including hot and cold weather placement procedures.
(1) Hot weather placement (air temperatures above 90°F). Comply with ACI N301
and 305.1 and as follows:
(a) Maintain concrete temperatures below 85°F at time of placement.
(b) Fog spray forms, steel reinforcement and subgrade just before placing concrete. Keep subgrade uniformly moist without standing water, soft spots or dry areas.
(2) Cold weather placement. Comply with ACI 306.1 and as follows:
(a) Protect concrete work from physical damage or reduced strength that could be caused by frost, freezing actions or low temperatures as soon as achievable, without causing damage to the desired finish.
1. When average high and low temperature is expected to fall below 40°F for three consecutive days.
2. Do not use frozen materials or materials containing ice or snow. Do not place concrete on frozen subgrade or subgrade containing frozen materials.
3. Do not use calcium chloride, salt or other materials containing antifreeze agents or chemical accelerators unless otherwise specified and approved in the mix design.
(B) Ensure reinforcements, inserts, embedded parts and formed joints are not disturbed during concrete placement.
(C) Place concrete in uniform layers, horizontal, six to eight inches thick. Place concrete continuously between predetermined construction joints shown on drawings (if called for). Piling up of concrete in forms to cause separation or loss of ingredients is not permitted.
(D) Do not deposit concrete which has partially set or hardened. Remove hardened or partially hardened concrete which has accumulated on forms or reinforcement. Do not place concrete on previously deposited concrete which has hardened sufficiently to cause formation of seams or planes of weakness within respective member or section except as specified.
(E) Deposit concrete as nearly in final position as practical to avoid rehandling. Exercise care to prevent splashing forms or reinforcing with concrete. Do not permit concrete to drop freely a distance greater than three feet. Where longer drops are necessary, use chute, tremie, or other conveyance to help avoid separation.
(F) Do not deposit concrete into excavation where water is standing. If place of deposit cannot be successfully pumped dry, place through tremie with outlet end near bottom of place of deposit.
(G) Do not deposit concrete when plasticity, measured by slump test, is outside specified limits. The addition of water to increase slump will not be permitted.
(H) Vibration. As soon as concrete is deposited, thoroughly agitated with mechanical vibrators and suitable hand tools to work mixture into corners of forms and around reinforcing and embedded items. Use mechanical vibrators with minimum frequency of 9,000 revolutions/minute. Do not over vibrate or use vibrators to transport concrete within forms. Insert and withdraw vibrators at approximately 18 inches apart. At each insertion, vibrate generally five to 15 seconds, sufficient to consolidate concrete but not long enough to cause segregation. Keep spare vibrator on job site during concrete placement operations. Do not insert vibrator into lower courses that have begun to set.
(I) Excessive honeycomb or embedded debris in concrete is not acceptable.
(J) Concrete shall be placed within 90 minutes of batching. If ambient air temperatures are above 80°F, the batch time shall be lowered to 75 minutes.
(Ord. 16-2020, passed 12-7-20)