1. In terms of concrete aggregates, be sure to visit ready-mixed concrete plants, and make sure
rock types are proper and particle size distributions or test values of aggregates meet the
standard.
2. Prepare standard samples of predetermined aggregates, and control the acceptance of
aggregates at the time of carrying-in so that only aggregates matching the standard samples
can be accepted.
3. Measure the surface moisture percentage and the moisture content of aggregates (especially
fine aggregates) in the proper way, and confirm that the volume of water is properly corrected
at the time of the measurements.
4. Ensure the accuracy of leveling (lean) concrete under concrete slab is kept within +5~-15mm,
and secure the appropriate thickness of concrete cover for upper reinforcing bars.
5. After concrete is cast, protect it from direct sunlight and strong winds, and it has to be
wet-cured for the predetermined period of time.
6. If necessary, consult Building Technology Dept. about concrete aggregates or mix proportions.
7. In terms of structural slab, have a discussion with the structural designer about the preventive
measures such as expansion joints or crack absorbing bands.
8. Regarding both structural slab and slab-on-grade, prior to casting concrete, draw up method
statements including finish and obtain approval from the designer.
In addition, be sure to carry out the instructions issued on March 20, 2015 (Memorandum 14-22
Concrete Slab Defect Prevention [Directive]) as well.