specs

Section 03300
Page 6
B. Conveying:
1. Prevent separation, segregation and loss of ingredients.
2. Convey concrete from mixer to place of final deposit as rapidly as possible.
3. Take special precautions with belt conveyors to prevent segregation of ingredients, drying and rise in
temperature during conveying.
4. Pumps or pneumatic equipment shall have adequate pumping capacity. Slump loss due to pumping shall
not exceed 2 inches. Do not convey concrete through pipes made of aluminum or aluminum alloy.
5. Thoroughly clean conveying equipment at the end of each placement sequence.
C. Depositing:
1. Place concrete continuously in horizontal layers not more than 12 inches deep. Exercise care to avoid
seams or weakened planes within the concrete. Deposit concrete into (not away from) previously
deposited concrete.
2. Do not place fresh concrete on partially hardened or contaminated concrete.
3. Do not place concrete which has partially set.
4. Exercise care to avoid splashing forms and reinforcing with concrete.
5. Place concrete in forms as near as possible to its final position, do not transport in the forms with vibrators
or screeds.
6. Do not drop concrete directly into standing water, use a tremie with the outlet near the bottom of the place
of deposit.
7. Use tremies, chutes or hoppers to place concrete where a vertical drop greater than 5 feet is required.
8. Do not place concrete when slump tests indicate plasticity that is greater than required limits.
D. Consolidating:
1. As soon as concrete is deposited, thoroughly agitate by means of mechanical vibrators and suitable hand
tools, to work the mixture well into all parts and corners of the forms, and entirely around the
reinforcement and inserts. Consolidation of concrete shall be in accordance with ACI 309.
2. Mechanical vibrators shall have minimum frequency of 7000 revolutions per minute.
3. Do not over-vibrate concrete or use vibrators to transport concrete within forms. Insert vibrators
vertically at frequent intervals, do not drag vibrators through concrete.
4. Do not insert vibrators into lower courses that have begun to set.
5. Maintain spare vibrators on the job site during all concrete placing operations.
E. Bonding:
1. Before depositing new concrete on or against previously deposited concrete which has partially or entirely
set, thoroughly clean and roughen surfaces to receive fresh concrete.
2. Re-tighten and thoroughly clean forms and reinforcement.
3. Apply 1 to 2 inches of grout to concrete surfaces. Grout shall be of identical mix to concrete without
coarse aggregate.
4. Deposit new concrete before grout attains initial set.
3.03. APPLICATION
A. Construction Joints
1. Each unit of structure (footing, slab or wall) shall be monolithic in construction except where specifically
required to be otherwise.
2. Slabs-on-grade in auditoriums shall be placed in a checker-board fashion as shown on the plans.
3. Where required, construction joints shall be located near the midspan of slabs.
4. Construction joints shall be located only where required or shown on accepted submittals.
B. Weather Conditions:
1. Cold Weather: Temperature of concrete delivered at job site shall conform to the following:
Air Temperature
Concrete Temperature
30 to 45 degrees F. 55 to 90 degrees F.
0 to 30 degrees F. 60 to 90 degrees F.
Below 0 degrees F. 65 to 90 degrees F.
a. Water heated to above 100 degrees F shall be combined with aggregates before cement is added. Do
not add cement to water or aggregates having a temperature greater than 100 F.
b. Conform to ACI 306.
c. When the outdoor temperature is less than 40 degrees F, maintain temperature of concrete at not less
than 50 degrees F for required curing time.
2. Hot Weather: Temperature of concrete delivered at job site shall not exceed 95 degrees F. Add ice to
NAPA CENTURY CENTER XD 12
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