Cold Weather Curing Concrete Flatwork

[jfklos]

A 10'x70' concrete driveway was poured at 60 degrees. True to Minnesota's weather, within 36 hours the air temp dropped to 20 deg. The driveway was left uncovered and the temperature of the concrete at 36 hours was 30 degrees and 27 degrees during the next 24 hours. A water hose on top of concrete was frozen solid within 36 hours.

Concrete supplier provided 6 bag mix, calcium accelerator and microfibers and recommended protection against freezing for 30 days.

Concrete installer said no insulation needed - the cold weather mix is sufficient.

Surface 1 year later is full of popouts and scaling.

Are the surface defects related to the cold weather during initial cure?

Would defects be limited to surface only? Or should larger cracks be expected?

 

[Ron]

Popouts are likely related to early coarse aggregate fracture due to freezing. This is usually limited to near surface issues.

You should see some cracking as a result of the freezing. Overall, the long term durability of the concrete and particularly the surface will be adversely affected.

 

[DRC1]

Why was there a water hose on top of the concrete?

 

[dik]

Check the aggregate type for 'popout' material, too.

Dik

 

[concretemasonry]

Was there any air entrainment?

Major Minnesota suppliers may not even deliver concrete for a slab unless it is 4000 psi(some 450psi) with 5% air entrainment.

Some suppliers will deliver less if the contractor signs a waiver (carried by the driver)before placement the eliminate the supplier responsiblity. The reason for this is to eliminate the supplier - contractor conflict where the supplier has no control over the placement/finishing/curing, which can be the major cause of future problems. - The use of fibers and accellerants do not move the responsiblity from the contractor, since he orders the concrete.

Proper inspection and specification is critical. Locally, there are fewer concrete problems with residential slabs as opposed to commercial slabs because of the "hard-nose" supplier attitude. A good supplier does not want to argue with a customer.

 

[vollEngineer]

you guys doing homework over here? LOL

Is the freeze/thaw cycle as simple as an area that ever reaches freezing temperatures and above-freezing temperatures? (like everywhere in the US?) or is there a special threshold?