ACI 305.1-14 Specifcation for Hot Weather Concreting.
3.3—Qualifcation of concrete mixture 3.3.1 Qualifcation of a concrete mixture with a maximum concrete temperature that exceeds 95°F shall be supported by either past feld experience or by preconstruction testing. 3.3.2 Acceptance of a proposed maximum fresh concrete temperature that exceeds 95°F, supported by past feld expe- rience, shall be based on similar production conditions, materials, constituent proportions and temperatures, and concrete delivery time. 3.3.3 Acceptance of a proposed maximum fresh concrete temperature that exceeds 95°F, supported by preconstruction testing, shall require materials similar to those proposed for use and tested under conditions that simulate the anticipated production and concrete delivery conditions of the project. 3.3.4 Laboratory trial batch—Batch the laboratory concrete trial mixture within 3°F of the proposed maximum fresh concrete temperature and mix in accordance with ASTM C192/C192M, except as modifed herein. If neces- sary, move the laboratory mixer into an enclosed, heated, and ventilated space; use heated mixing water; or both, to achieve and maintain the proposed maximum concrete temperature. For drum-type mixers, the concrete mixture shall remain in the mixer for 47 minutes after completing the 3-minute initial mixing period, unless specifed otherwise. During the 50-minute period, cover the mixer opening with a nonabsorbent material such as plastic to prevent moisture loss, and rotate the mixer continuously at an agitation speed of 6 to 8 rpm. For laboratory mixers without speed adjust- ments, simulate agitation by rotating the mixer continuously at a drum angle between 45 and 75 degrees from horizontal. At the end of 50 minutes, mix the concrete mixture at mixing speed as designated by the manufacturer for 2 minutes. For pan-type mixers, the concrete mixture shall remain in the mixer for 41 minutes after completion of the initial 3-minute mixing period. During the 44-minute period, the mixer shall cycle through periods of rest for 5 minutes, and then mixing for 1 minute. During the rest period, cover the mixer opening with a nonabsorbent material, such as plastic, to prevent moisture loss. At the end of 44 minutes, mix the concrete mixture at full mixing speed as designated by the manufacturer for 2 minutes. During mixing and agitation periods for both drum-type and pan-type mixers, the addition of water, chemical admix- ture, or both, to adjust slump is permitted, provided that the specifed concrete mixture w/cm is not exceeded. Check the slump of the concrete mixture during the middle third of the 50- or 44-minute laboratory trial mixing period and adjust as needed.ACI 305.1 pdf download.