Construction Building Envelope and Interior Finishes Databook

When low slumps, created in conjunction with minimum water requirements, are used with correct placement procedures, the shrinkage of concrete will be held to a minimum. Conversely, high water content and high slumps will increase shrinkage. A study at the Massachusetts Institute of Technology, as reported by the Portland Cement Association, indicated that for every 1% increase in mixing water, shrinkage of concrete increased by 2%. This study produced the following char, showing the correlation of water and cement content to shrinkage.
| Cement Content Bags/cubic yard | Concrete composition | Aggregate | Water + air | Water cement ratio by weight | Slump (inches) | Shrinkage (av. 3 3 10* prism) | ||
|---|---|---|---|---|---|---|---|---|
| Cement | Water | Air | ||||||
| 4.99 | 0.089 | 0.202 | 0.017 | 0.692 | 0.219 | 0.72 | 3.3 | 0.0330 |
| 5.99 | 0.107 | 0.207 | 0.016 | 0.670 | 0.223 | 0.62 | 3.6 | 0.330 |
| 6.98 | 0.124 | 0.210 | 0.014 | 0.652 | 0.224 | 0.54 | 3.8 | 0.0289 |
| 8.02 | 0.143 | 0.207 | 0.015 | 0.635 | 0.223 | 0.46 | 3.8 | 0.0300 |