CONCRETE CONSTRUCTION TABLE OF CONTENTS PAGE I ...

Polaris
Engineering
Standard
430.1
Rev.: 0
Page: 4 of 9
Date: 07/07/09
V. MIXING AND PLACING
A. Job-Mixed Concrete
1. Job-mixed concrete shall be in accordance with ACI 304R.
2. Rotate the mixer at a speed recommended by the mixer manufacturer.
Continue mixing for at least 1-1/2 minutes after all materials are in the
mixer.
3. Mix all concrete until there is a uniform distribution of the materials and
discharge completely before recharging the mixer.
B. Ready-Mixed Concrete
Mix and deliver Ready-mixed concrete in accordance with ASTM C94.
C. Placing Concrete
1. Deposit concrete as near as practical to its final position to avoid
segregation of aggregates due to rehandling or flowing. The concrete
must be plastic at all times and flow readily into the spaces between
reinforcing bars. Water in excess of approved batch quantities shall not be
added for this purpose; however, appropriate admixtures approved by the
Client and/or Polaris Engineering may be used to improve flow.
2. After concrete placement has started, continue operation until the section
is completed except as prohibited or permitted by Section VI.
3. Do not drop concrete vertically more than eight feet. Use drop chutes for
higher lifts. The chute shall have a diameter of at least eight times the
maximum aggregate size and shall be positioned so that the concrete will
drop vertically.
4. Do not start placing concrete in supported elements (beams or slabs) until
the concrete previously placed in columns or walls is no longer plastic and
has been in place at least two hours.
5. All concrete shall be thoroughly consolidated by suitable means during
placement, and shall be thoroughly worked around the reinforcement and
embedded items and into the corners of the forms.
6. Install all embedded items such as anchor bolts, sleeves, inserts,
equipment bed and slide plates in their correct location and secure against
displacement.