Cold weather Concrete protection after curing 1

[wtp]

What is the proceedure in protecting concrete after cure.
What should be use to prevent shear pockets and anchor bolt sleeve from freezing and damaging the concrete.

 

[Ron]

In general, concrete should be kept above about 50F during placement and for the initial curing period. As time and curing continue, the temperature becomes less critical. At least for the first 7 days or so, don't let the concrete temperature get down to freezing.

Specific guidelines are provided in ACI 306, Section 5, including a table (Table 3.1) on minimum temperatures at various times in the placement, initial, and final curing of the concrete.

 

[wtp]

Other than propylene glycolant antifreeze what else can be use to prevent shear keys and anchor bolt sleeves from freezing.

 

[ronster]

Insulation blankets

 

[JohnGn]

In-place temperature monitoring is being used increasingly to track actual temperatures of the curing concrete. In addition to learning temperatures, one can couple the thermal data to known strength-gain data to arrive at an accurate estimate of the in-place maturity, which can then be correlated to an in-situ strength. This procedure is known as maturity testing. Knowing the strength at any time during early-age curing can be very helpful in determining just what, if any, protective measures might need to be taken.

In my experience, only concrete that has been grossly unprotected when cold temperatures are experienced is in any jeopardy of actually freezing, at least for the first 3 days. Simple insulating blankets are often sufficient to keep the concrete warm enough to prevent free water from freezing. In fact, the actual freezing point of concrete is well below 0 C, somewhere near -12 and -14 C. Also, air-entrained concrete can likely withstand one freeze-thaw cycle once it reaches about 500psi, and multiple cycles once it reaches 70% of it's design strength.

Hope this helps.
--John Gnaedinger