Wet Cure Concrete
Wet Cure Concrete
(OP)
I received a question from a contractor asking to wet cure a slab on grade. However, they wanted to use Visqueen in lieu of burlap. They propose to soak the slab and cover it in visqueen for 5 days. There are no cure and seal products being used for this slab.
I had a few questions:
1. Does this seem like a possible option? My first questions is how/when would they "soak" the slab.
2. When/how are control joints made when you wet cure a slab?
3. Any reference material you could point me towards? Normally I would expect burlap to be wetted for about 7-14 days but the control joints need to be placed within a day.
Thanks!
I had a few questions:
1. Does this seem like a possible option? My first questions is how/when would they "soak" the slab.
2. When/how are control joints made when you wet cure a slab?
3. Any reference material you could point me towards? Normally I would expect burlap to be wetted for about 7-14 days but the control joints need to be placed within a day.
Thanks!






RE: Wet Cure Concrete
1. To add water just lift the edge and add as needed. Evaporation is darn near zero.
2. Saw joints early on, preferably the day of the pour. Shrinkage starts only hours after placement. There are tools to do this even before you can walk on it.
3. Burlap seems out of date to me. How abut curing compound instead?
http://www.cement.org/cement-concrete-basics/worki...
RE: Wet Cure Concrete
Softcut sawing is the way to go, if you are sawing control joints. Saw, then apply the sheeting.
Most commonly used curing compounds are of limited value. The acrylic ones are useless. Chlorinated rubber does a pretty good job, but is toxic. Wax emulsion also works. But with the last two types, adhesion of finishes is problematic unless the compounds are removed first.
RE: Wet Cure Concrete
RE: Wet Cure Concrete
Curing compounds aren't great. They are often not applied correctly by the contractors. You need to seal the entire surface without any gaps, and even then, the best you can achieve is stopping the evaporation of moisture. With wet curing you add additional moisture to continue the hydration reaction as the internal water is used up.
RE: Wet Cure Concrete
Does 5 days seem to be enough time?
EIT
www.HowToEngineer.com
RE: Wet Cure Concrete
I hope this helps!
RE: Wet Cure Concrete
RE: Wet Cure Concrete
I think ACI 5.11 is what Jike was quoting and that does sound correct. I suppose this is what I need.
Is there a cold weather provision in there? It's currently freezing here! I should probably do a little more homework at this point.
EIT
www.HowToEngineer.com
RE: Wet Cure Concrete
I think ACI 5.11 is what Jike was quoting and that does sound correct. I suppose this is what I need.
Is there a cold weather provision in there? It's currently freezing here! I should probably do a little more homework at this point.
EIT
www.HowToEngineer.com
RE: Wet Cure Concrete
Here is a link for cold weather concreting
http://www.cement.org/for-concrete-books-learning/...
RE: Wet Cure Concrete
Search the magazine's archives for other info: Link
www.SlideRuleEra.net
www.VacuumTubeEra.net
RE: Wet Cure Concrete
2. ACI-306 Cold Weather Concreting
3. ACI-308 Recommended Practices for Curing Concrete
RE: Wet Cure Concrete
EIT
www.HowToEngineer.com
RE: Wet Cure Concrete
RE: Wet Cure Concrete
RE: Wet Cure Concrete
My understanding is that to continue hydration (the cement never 100% hydrates), you need 80% relative humidity in the pores. You want to provide a favourable environment for the hydration to continue as much as possible to achieve durable concrete by reducing the size and continuity of the pores. Adding water at early ages will help keep the pores in the cover full to allow the reaction to continue and improve the degree of hydration. At lower w/c ratios, the need for this is even greater. This is also why some high performance concretes will utilize porous saturated aggregates to provide "internal curing" to replenish the pores.
Really, my point was that when it comes to curing, more water = better.
RE: Wet Cure Concrete
RE: Wet Cure Concrete
Below w/c 0.5, concrete does use external water to hydrate. From "Properties of Concrete" by Neville,
RE: Wet Cure Concrete
Keep in mind that the strength of a mixture is established by moist-cured cylinders... See attached for plots of strength vs. moist cure time for concrete.
The strength loss at low relative humidities is due to a combination of microcracking due to shrinkage, and slowed or stopped hydration. Maintaining free water at the concrete surface addresses both.
RE: Wet Cure Concrete
RE: Wet Cure Concrete