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 (30)

Massé François says:

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.

Sakrete says:

24 hours is a safe bet, Massé.

Edward says:

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,

Sakrete says:

Always recommend waiting the full 28 days before applying any sort of coating to a fresh concrete slab.

Dale Gilmour says:

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 🏕

Sakrete says:

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.

rocky says:

is “drypouring” concrete a legitimate method of building a small slab using your product?

Sakrete says:

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!

Gordon says:

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?

Sakrete says:

If you’re exceeding 2″, regular concrete is the way to go!

Jim says:

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

Sakrete says:

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!

Raul says:

Does rebarb less than 6 inches deep reenforce the concrete? Is it even recommended for that depth?

Sakrete says:

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!

Mark Weaver says:

How long should I wait to install anchors in a newly poured 4 inch concrete slab?

Sakrete says:

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!

Robert Aldrich says:

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

Sakrete says:

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.

Mason Contracting says:

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?

Sakrete says:

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!

Mason Contracting says:

What is psi strength of Sakrete Concrete at 1 week of curing?

Sakrete says:

You’ll be hitting 2,500 psi after a week, meaning that it’s pretty much ready for full-scale use.

Chris says:

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

Sakrete says:

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!

Bob says:

Will sand mix bond to a set sand mix? Is there something I should add to help it bond?

Sakrete says:

Yes, that is correct although it is advised to use a bonding agent in this application. See our Capping Damaged Slabs Project Guide for more information.

Scott Walker says:

Poured a sidewalk today, the first 10 bags were fine but the next 10 were missing the stone aggregate. Nothing more than cement and sand. Middle of the project so couldn’t stop or make the 30+ minute trip to Lowe’s. What in the world happened? Can I give you a bag number or anything to help figure this out? Question, will this section simply crumble apart or will it be fine. Have 10 of the remaining bags but scared to complete the next section. Broom finish so it doesn’t look terrible; little sandy compared to the previous section. Planning to acid stain so not to worried about a color difference. Need some help and guidance.

Sakrete says:

Scott, we apologize for the quality issue! We’d like to know where this product was purchased so we can track it back to the plant and investigate the quality issue. In the meantime, we will pass your info along to our customer support team to get you a refund on those 10 bags. As for the additional 10 bags, check them for defects if you continue the job. If they are defective, we’ll make it right.

Tony Brennan says:

Can I tar over the concrete before the 28 days of curing?

Sakrete says:

Tony, we would advise to not tar over the concrete before the full 28 days of curing that the concrete needs.

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