 |
 |
 |
 |
|
|
|
|
|
|
Bubbles
that
form during the concrete mixing process are kept steadied and small by
air entraining admixtures. The admixture forms a tough soapy film
over the bubbles that keeps them from joining together and keeps out
water.
The mixing process spreads the bubbles throughout the concrete. The
resistance of hardened concrete to freezing
and thawing in moist conditions is improved by entrained air. Pressure
on expanding and
freezing water forces it out of the concrete capillaries and pores. It
enters the entrained air spaces without expanding inside the concrete
and cracking it. When the water thaws it returns to the capillaries
and pores. Deicers used for ice and snow removal cause surface scaling
of non entrained concrete. Deicer hydraulic and osmotic pressures
are greater than the pressures exerted by the water in the concrete.
Entrained air spaces relieves these pressures and prevents scaling. |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |