______________
fig. 1
Troubleshooting
Concrete
Nebraska Concrete &
Aggregates Association
Jereme Montgomery
4. Vapor Retarders
History
3. Floor Moisture
Depends on ...
Water/Cement Ratio
Density of the concrete finish
Thickness
Exposure of moisture
Method of curing
Ambient conditions above the slab
How Long Does it take
for concrete to dry?
Take the ground out of play!
Fallacies
______________
______________
Concrete's
10. Plastic Shrinkage
AIR temp
Wind Speed
Concrete temp
Humidity
predicting
your
risk
What can be done?
9. Cracking
___________
____________
Minimize Random Cracking
Keep joints short
Saw joint timing
Uniform thickness
Fine graded subbase
8. Slab Reinforcement
7. Evaporation
Retarders
6. Slab Curling
5. Floor Flatness
2. Curing is for Sissies
1. Scaling
Project "Cool Concrete"
Minimizing Curling Effects
FF/FL
FF = Bumpiness
FL = Tilt or Pitch
F-Numbers Handbook:
The 40 Most Asked Questions about F-Numbers
What the..?
FF/FL vs Straightedge
No ASTM Standards for
straightedge testing
FF/FL measured within 72 hours
ASTM 1155 measures
contractor compliance
FF/FL is not measured across cnst joints
ACI 302-69
ACI 302-89
ACI 302 - April 2001 Update
ACI 302.2-06
Place VR Directly under concrete
Use a blotter layer
Place VR Directly under concrete
Guide for Concrete slabs that Receive Moisture-Sensitive Floor Coverings
What causes scaling?
high w/c
improper air
improper finishing
lack of curing
Deicers
its not your 
fathers concrete
Curing is a means to maintain moisture and temperature
Is curing the same as drying?
Proper Curing Provides:
>Reduce Early Cracking
>Accelerate Strength Gain
>Improved Wear Resistance
>Improved Durability
>Reduced Permeability
>ASTM C 309
>ASTM C 1315
>ASTM C 171
Pre-Construction
Meeting
ONSITE
8:00am!
1. Use lowest possible w/c
2. Keep joint spacing at 24x thickness
3. Use largest maximum size aggregate or
use maximum amount of coarse aggregate
4. Reinforce the slab
or...
Shrinkage reducing admixtures
Shrinkage compensating concrete
Post Tension slabs
Bathtub?