Specifications

07/22/10 03001-6
B. A shorter mixing time than specified in ASTM C94 may be required. When the air temperature is
between 85 and 90 degrees F, reduce the mixing and delivery time from 90 minutes to 75
minutes, and when the air temperature is above 90 degrees F, reduce the mixing and delivery time
to 60 minutes.
Cover reinforcing steel with water-soaked burlap if it becomes too hot, so that the steel
temperature will not exceed the ambient air temperatures immediately before embedment in
concrete. Wet forms thoroughly before placing concrete.
Do not use retarding admixtures without the written approval of the Engineer.
3.09 FINISHING CONCRETE
A. Rough finish for concrete surfaces not exposed to view in the finish Work or covered by other
construction.
B. Strike - off smooth and finish with a texture matching adjacent formed surfaces at tops of walls,
horizontal offsets and similar unformed surfaces occurring adjacent to formed surfaces.
C. Provide a uniform smooth rubbed finish on exposed formed concrete walls, columns, and beams.
D. Float finish monolithic slab surfaces that are to receive trowel finish or other finish.
1. Trowel Finish: After floating, begin first trowel finish operation using a power-driven trowel.
Begin final troweling when surface produces a ringing sound as trowel is moved over surface.
Consolidate concrete surface by final hand-troweling operation, free of trowel marks, uniform
in texture and appearance, and with a surface plane tolerance not exceeding 1/4" in 10 feet
when tested with a 10 foot straight-edge. Grind smooth surface defects which would show
through applied floor covering system.
2. Non-slip Broom Finish: Apply non-slip fine-hair broom finish to sidewalks, driveways,
handicap ramps, curbs, or other items as noted on the Drawings.
3.10 CURING
A. Protect freshly placed concrete from premature drying or heat, and maintain without drying at a
relatively constant temperature for a period of time necessary for hydration of cement and proper
hardening.
B. Start initial curing as soon as free water has disappeared from concrete surface after placing and
finishing. Weather permitting, keep continuously moist for not less than 72 hours.
C. Continue curing for a least 7 days and in accordance with ACI 301 procedures. Avoid rapid
drying at end of final curing period.
D. In lieu of moist curing, spray a clear liquid membrane curing compound on all new concrete
immediately after initial set. Rate of application to be 200 square feet per gallon or as
recommended by the manufacturer.
3.11 TESTS
A. Testing and analysis of concrete will be performed by an independent testing laboratory.
B. Test firm will take cylinders and perform compression tests in accordance with ASTM C31,
ASTM C39, and ASTM C192.
C. Number of cylinders and frequency of tests will be designated by the Engineer.
D. One slump test will be performed per ASTM C143 for each set of test cylinders taken.