How long do footings need to cure

The reason behind the footings being lifted out of the ground even if you were to make them deeper than the frost line are things call ice lenses which are horizontal pocket of moisture or water that can catch onto the rough surfaces of footing and when frozen lift the foundation up. I would use smooth sided cardboard tubes to contain the concrete in the hole and keep it above the bottom of the hole between 6 and 12 inches that way the concrete at the bottom of the hole will be wider than the top and create a sort of anchor for the foundation.

The holes for the footing should be flared out at the bottom to create a footing that is wider at the bottom than the top this will help with frost heave in cold areas and provide a bigger footprint for greater stability. Direct water away from the foundations by mounding up the dirt around them after all the site has been backfilled and levelled. This is entirely up to you but I have a few tips for you if you are going to pour more than a couple of footings then I would recommend getting premixed concrete not only will you save the effort of mixing all that concrete by hand or in a concrete mixer but generally the premixed concrete will be better and you can specify the exact type of concrete for your location and use.

But you need to be organized and get some willing volunteers to help especially if your deck is in the backyard with limited or no access for a concrete truck, in that case, you will need some wheelbarrows to get the concrete into the holes. It is probably better to put the concrete into the round tubes you have secured in place using shovels because concrete is heavy and it is quite easy to dislodge or move the tubes and misalign the footings. Most premixed concrete suppliers will charge you extra if it takes too long to get the mix out of the truck so a quick careful placement of the concrete is essential.

When you are filling the tubes fill to about halfway and then use a piece of rebar to consolidate the concrete to get rid of any air pockets or voids. Fill the rest of the tube until it is slightly overfilled then use the rebar again to consolidate the concrete you could also tap the outside of the tube to consolidate and top up with more concrete and smooth the surface with an angle towards the outside to help water runoff. Now is the time to insert and align the brackets that the posts will sit in if you are putting the footings in before you build the deck.

If on the other hand, you are putting in the permanent posts after building the deck then you will already have the brackets fixed to the posts and they are aligned in the centre of the formwork tube and it is a simple matter of pouring the concrete around them. Concrete contains lime and can be an irritant on your skin so I like to were eye protection and waterproof gloves when I use concrete.

Gravel allows water to drain into the ground below. When packed tightly, however, the gravel doesn't shift beneath the concrete. Junko Oesterle Supporter. When can I walk on new concrete? Walking : We request you not walk on your concrete for at least 24 hours after the concrete has been finished. Thereafter if it is used or walked on it will scuff and scratch easily for at about 3 days.

So avoid dragging your feet and keep pets off for this duration as their nails may scratch or gouge the new concrete. Elhadji Diaz Caneja Beginner. When can I remove formwork? The removal of formwork also called as strike-off of forms in which concrete is poured. The formwork should be removed only after when concrete component achieves its sufficient strength. The care should be taken during the removal of formwork to ensure the stability of the remaining formwork. Nicol Sanchez Moreno Beginner.

How do you strengthen concrete? How to Make Concrete Even Stronger. Reinforce a concrete pour with rebar or steel mesh. Consider the weather when pouring concrete. Mist new concrete with a water hose every hour on the day you pour it, and at least three times a day for the next two days.

Ask the concrete company not to add calcium to your concrete on a cool day. Heidi De Llanos Beginner. Should I cover concrete from rain? Pouring Concrete vs Pouring Rain. If the rain occurs when the concrete is fresh about hours after mixing , the surface should be protected from the rain. If the finishing process was recently completed, rainwater may not cause damage as long as it is not worked into the surface and the slab is left untouched.

Ask A Question. Co-authors: 5. In fact, if the concrete hasn't reached the minimum strength required by code in 7 days, it's unlikely to get there. The IRC requires a concrete footing to have a minimum compression strength of 2, psi which is a low value and easy to achieve most specifications would be higher. I won't characterize that earlier claim since it speaks for itself. As far as "respectable" architects are concerned, I have linked my grad school textbook as evidence of my training in this subject, although I would normally defer to an engineer in professional practice.

The subject at hand is briefly discussed on page 5. Of course, my book was a much older edition. It is important to understand that "curing" is an optional construction procedure rather than a physical state to be achieved.

The use of phrases like "the concrete is cured" is shortspeak indicating that the desired period of moisture control is over. The design strength is just one of many variables considered in the selection of a curing method and time period.

I once had a bad batch of concrete poured in the mat foundation of a large hospital addition. Unfortunately, it was an all day pour so it threatened to delay the project. In a big meeting of all the involved parties the concrete testing engineer announced that there was enough fly ash in the mix that steam curing might bring it up to the design specification.

I had done an existing conditions survey of the adjacent buildings as part of the architectural design process and told them there was an unused steam line immediately adjacent to the bad pour. People flew out of the trailer to tent and steam the concrete mat. When the test results came in the ready mix owner was so choked up he couldn't speak.

Now there is someone who is unlikely to bad mouth engineers and architects. Here is a link that might be useful: Concrete design textbook. So doing research to determine an effective time short of forever for measuring the strength of concrete is arbitrary? Variation will occur during assembly away from the ideal methods. We use the derating of absolute values to account for this. Choosing 28 days is far from arbitrary, but based on much research to establish a reasonable time based on mix and applications.

My point was that the 28 day mark represents a testing standard based on professional concensus rather than representing the point at which the concrete work can support a load.

To say a footing cannot be partially loaded before the 28 day mark indicates a staggering misunderstanding of concrete design and construction. At any rate, it should be clear that the contractor in question either has another reason for delaying the OP's project an additional 3 weeks or he doesn't know what he is doing. Either possibility would concern me greatly. This isn't rocket science; it's just a house footing. Excellent discussion. Who the heck is Manhattan42?

He writes as if he was a pro but says things that don't make much sense. I've built 2 houses and the builder of the first did want to wait 2 weeks crawlspace. This was a tract build. Flash forward 10 years and the custom builder just kept on trucking basement. He was also the one who explained the concept of purposely slowing the cure with water The common assumptions about concrete curing are interesting. Most people and many builders think curing is the process by which concrete becomes fully hydrated ie hydrated enough to meet the design specifications but the term only referrs to the use of techniques to prevent the evaporation of water from the concrete in order to increase the hydration in the early part of that process when most of the concrete strength is achieved.

Curing is a technique for boosting concrete strength and the need for it varies with the nature of the pour. In the case of a structural footing, little curing is necessary to meet the design specification but in the case of a slab curing techiniques are critical for strength, crack prevention, and surface quality. So, the "cure isn't slowed with water"; water spray, or other techniques, are used to guarantee greater, more complete hydration of the cement in the concrete mix during the first 2 to 7 days after the pour.

Interesting I came across this post. We had our footers poured last Thursday and rebar in place, that evening it rained all night and in to Friday morning. On Monday they had all the forms in place, Tuesday poured and today took the forms off. Temps are around 40 during the day and 30 something overnight and they are calling for snow this weekend.

I only hope we have no issues in the long run and that we didn't rush things. At this point though it's too late to worry about it. Standard engineering practice in considering the curative time for concrete or other masonry is 28 days. You should try reading the ACI documents that establish the requirements for concrete construction instead of making up a lot of specious nonsense.

A national builder is building a single family home across the street from my residence. Here is what I've observed so far. The slab, footers, and foundation were poured on a Friday during a snowstorm.

The concrete was poured on top of approximately " of fresh snow. The following Monday the builders returned and started to lay block. Over the 2 day weekend, the ambient temperature never got above freezing. Is this considered acceptable building practice?

Calcium Chloride can be added to the mix to allow pouring at lower temperatures, but surface protection from accelerated cooling is often still required. Most residential work is not loaded enough to matter, and the chief problem that would occur would be spalling of the surface if it was frozen and did not hydrate correctly.

And the slang reference to 'curing' as the required period for adequate hydration works fine and is understood in the field. Simple keying of footers was used for many years. Rebar to tie walls to footers is still not needed or required in many locations. Even the use of rebar in footers is not a universal requirement though I put it in corners no matter what. Can anyone tell me how?

More rebar, or rebar in certain spots? None of above? Concrete can get shrinkage cracks as it hardens, but folks do not usually like the grooves that can be put in to create a weak spot for preferential shrinkage cracking. Cracks that are even on each side are not usually from settling.

Settling means the earth compacted or shifted under part of the concrete. This produces a concentrated load think of a cantilever and a crack occurs. Most commonly the crack is wider at the top, narrower at the bottom, and the surfaces on each side are no longer flat with respect to each other. Settling occurs typically when the soil's weight bearing capacity is overloaded and it compacts further.

It can also be caused by shifts in underground water flow, expansive soils that shrink when the dry out, and some other conditions I cannot even think of at the moment. Wider footers can reduce the ground load, but often cannot by themselves eliminate all the possible causes of settling. You need to design the footings and slabs for the foundation configuration, the winter frost depth, the subsurface conditions, the anticipated loads, the weather during construction, and any special design conditions using published codes and guides, the best of which is ACI That task should be done by an experienced competent designer rather than a homeowner but you can buy a copy of ACI and learn a lot because it is relatively simple and straightforward.

Here is a link that might be useful: ACI Does anyone know of a reliable source? The article points out that concrete is cheaper than rebar due to labor costs , and that the ACI table tells builders how to substitute one for the other. That's interesting. Do not start watering during the hottest part of the day because it could shock the concrete into developing surface crazing similar to a hot glass breaking when filled with cold water.

How soon should I water concrete after pouring? Read about properly curing concrete slabs. Water curing can be done after the slab pour by building dams with soil around the house and flooding the slab. The enclosed area is continually flooded with water. Ideally, the slab could be water cured for 7 days. Can you lay concrete on soil? Pack about 4 in. Can I drive on concrete after 3 days? It will take additional time before you can drive or park heavy equipment or machinery on your newly poured concrete, so make sure to wait at least 30 days.

When can I remove concrete formwork? The removal of formwork also called as strike-off of forms in which concrete is poured.

The formwork should be removed only after when concrete component achieves its sufficient strength. The care should be taken during the removal of formwork to ensure the stability of the remaining formwork. How do you seal new concrete?