when working with epoxy resins.
][3.4.3
Pumping
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NOTE: Pumping requires careful attention to mixture
designs and pumping procedures. Allow pumping when
other means of placement will be impractical or
expensive.
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ACI 304R and ACI 304.2R. Pumping shall not result in separation or loss of
materials nor cause interruptions sufficient to permit loss of plasticity
between successive increments. Loss of slump in pumping equipment shall
not exceed 50 mm 2 inches. Do not use pipe made of aluminum or aluminum
alloy. Avoid rapid changes in pipe sizes. Limit maximum size of coarse
aggregate to 33 percent of the diameter of the pipe. Maximum size of well
rounded aggregate shall be limited to 40 percent of the pipe diameter.
Take samples for testing at both the point of delivery to the pump and at
the discharge end.
]3.4.4
ACI 306.1. Do not allow concrete temperature to decrease below 10 degrees C
50 degrees F. Obtain approval prior to placing concrete when ambient
temperature is below 4 degrees C 40 degrees F or when concrete is likely to
be subjected to freezing temperatures within 24 hours. Cover concrete and
provide sufficient heat to maintain 10 degrees C 50 degrees F minimum
adjacent to both the formwork and the structure while curing. Limit the
rate of cooling to 3 degrees C 5 degrees F in any one hour and 10 degrees C
50 degrees F per 24 hours after heat application.
3.4.5
Hot Weather
ACI 305R. Maintain required concrete temperature using Figure 2.1.5,
"Effect of Concrete Temperatures, Relative Humidity, and Wind Velocity on
the Rate of Evaporation of Surface Moisture From Concrete" in ACI 305R to
prevent the evaporation rate from exceeding one kg per square meter 0.2
pound of water per square foot of exposed concrete per hour. Cool
ingredients before mixing or use other suitable means to control concrete
temperature and prevent rapid drying of newly placed concrete. Shade the
fresh concrete as soon as possible after placing. Start curing when the
surface of the fresh concrete is sufficiently hard to permit curing without
damage. Provide water hoses, pipes, spraying equipment, and water hauling
equipment, where job site is remote to water source, to maintain a moist
concrete surface throughout the curing period. Provide burlap cover or
other suitable, permeable material with fog spray or continuous wetting of
the concrete when weather conditions prevent the use of either liquid
membrane curing compound or impervious sheets. For vertical surfaces,
protect forms from direct sunlight and add water to top of structure once
concrete is set.
3.5
SURFACE FINISHES EXCEPT FLOOR, SLAB, AND PAVEMENT
3.5.1
Defects
Repair formed surfaces by removing minor honeycombs, pits greater than 600
square mm one square inch surface area or 6 mm 0.25 inch maximum depth, or
otherwise defective areas. Provide edges perpendicular to the surface and
SECTION 03311
Page 35
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