Pro Tip
Top 5 FAQs About Using Concrete
Concrete Insider answers frequently asked questions, submitted by our customers across the country. Our goal is to increase your expertise in concrete products and installation. Have a question of your own? Consult our technical team to identify the best products or discuss application techniques.
Top 5 Most Asked Questions about Using Concrete
1. How long does it take for concrete and mortars to cure?
It typically takes 28 days for most concrete and mortars to fully cure. Temperature, humidity and other factors can affect cure time. Always consult your product package for details.
2. What is the minimum temperature for using cementitious products?
The minimum temperature should be 40°F, which applies to air, mix and substrate. This temperature should not only take place during the application, but up to 24 hours after application.
3. Does it matter when water is added when mixing concrete?
When mixing concrete, you should always add water first in your mixing container, and then the bagged product.
4. How should you properly prepare your surface before pouring concrete?
Proper surface preparation is just as critical as choosing the right product. For new concrete slabs, excavate the area to remove grass and debris. Ensure that the excavated area is pitched in a direction where water will run away from the building. Mark the perimeter of the new slab with stakes and string a level line between them. This will help ensure the forms are level. Lay a gravel base in the excavated area (1 to 2 inches in depth) using Sakrete All-Purpose Gravel. This will help with any water flow or substrate movement and prevent the concrete from buckling. Remember to allow enough depth for both the gravel bed and a minimum of 4” inches of concrete. Place forms in the desired area using 2×4’s, assuring that they are level, square and all corners are sealed so no premixed material can escape once placed. Nail the forms together and remove the string. Now you’re ready to pour!
5. What time of year is best for laying concrete?
If you’re in a mild, year-round climate, you can lay concrete at any time as long as it meets the minimum temperature of 40 – 90°F. If your area experiences a more seasonal climate, the Spring or Fall are the best times of year for application.
Comments (24)
After having set a post 4feet in somotube with skaters fast setting concrete, how many hours must it NOT rain for the list to set correctly.
24 hours is a safe bet, Massé.
I just poured a 4’x8′ sakrete pad for a small shed, how long do I have to wait before I put a sealer on it? The store clerks at the big box stores mean well, but everyone has a different answer to this question. Please advise me on this next step… Correct one.
Thanks in advance,
Edward
Always recommend waiting the full 28 days before applying any sort of coating to a fresh concrete slab.
How does a concrete product like Sackreet take to dry in 4”x6” iron tube , 76” long ?
Except for a 3” dia. Fill hole on topside and perhaps two smaller holes on each end of my truck bumper, how would this ‘cure’ ?
I need this extra weight to provide better rear traction in winter .
Thanks, Pilgrim 🏕
Interesting question, Dale – not sure we can give you a hard and accurate answer on that one! It’ll definitely set, but not sure at what rate.
is “drypouring” concrete a legitimate method of building a small slab using your product?
Rocky, we really can’t stand behind the “dry pour” method. We’ve seen the YouTube videos, but have very low confidence in those slabs being of uniform strength and holding up for the long term. Plus, we’re just not sold on it being that much of a time or labor saver!
Be safe, do it the “hard” way!
I am increasing the height of a 4′ x 4′ concrete slab by 2 1/2″ due to minor flooding during extremely heavy rain. The slab is a walkway with little use. Would sand mix work for this application, or should I use standard concrete?
If you’re exceeding 2″, regular concrete is the way to go!
We installed sakrete in a post hole hole for a deck. After 24 hours I could push a screwdriver thru it. The temps were in the low 30s when we started. It did get warmer throughout the day but I’m concerned that it won’t get hard or be as strong. Thanks
Jim, low 30’s is pretty cold for concrete – you typically want no lower than 40F for 24 hours before AND after the pour to ensure you get good performance.
Ultimate strength won’t be an issue in this application, it’s just going to take quite a bit longer to set up!
Does rebarb less than 6 inches deep reenforce the concrete? Is it even recommended for that depth?
Raul, rebar is recommended for pretty much every structural slab – typically will only be 2″ below the surface in traditional 4″ slabs. And yes, it makes a difference!
How long should I wait to install anchors in a newly poured 4 inch concrete slab?
If you’re talking about mechanical concrete anchors that need to be drilled in, you should wait a MINIMUM of 7 days. The concrete is at about 75% of its total strength by that point, so it’s safe to drill into. That said, longer is always better!
Do you suggest watering slabs after pouring if so when and why I’ve heard of hotter places than Washington buy Seattle for example AZ CA TX that do i just don’t remember ever seeing it done in my area
Keeping a slab moist throughout its initial cure is critical. The cement in concrete is constantly using water to power the chemical reaction called hydration that gives concrete its strength. If the slab “runs short” of water, it can start hardening at different rates, which can cause cracks and spalling.
The name of the game is mitigating evaporation and keeping that chemical reaction fuelled, but there are several options for how to do it.
First option is to directly water the slab with a garden hose (some folks even “flood cure”!), second option is to cover the slab with plastic or burlap to trap moisture, and your third (and best) option is to use a curing agent like Cure ‘N Seal.
What is the psi Strength of Sacrete concrete at 1 week of cure, 2 weeks, 3 weeks? Full cure at 28 days is 4000psi. Does it hold true as 1000 psi, 2000 psi, 3000psi and final at 4000 psi?
Not exactly – bit more of a ‘hockey stick’ curve.
The rule of thumb is about 75% of final strength at 7 days – roughly 2,500 psi – then you’re in the high 90% range by 14. Very slow increases after that point all the way up to (and technically beyond) 28 days!
What is psi strength of Sakrete Concrete at 1 week of curing?
You’ll be hitting 2,500 psi after a week, meaning that it’s pretty much ready for full-scale use.
I’m replacing a chimney crown that will be 6’L x 2’W x (approx) 3″H. I’m doing this myself and can only use 5gal buckets for the pour. I’m using 60# bags of High Strength and I’m planning on pouring 2 – one sack batches at a time with approx 20min between each batch. I don’t have access to a Hydration Stabilizer and I’m worried I won’t get an even pour before it starts to set-up. Any recommendations?
Thank you
Chris, good news is that this really isn’t THAT big of a pour – should be about 5 bags. Pick a cool day, use cool water and you should be just fine.
Better yet, make yourself a mixing station on the roof to cut down on that batch time!