aci 318 curing requirement 1

[boffintech]

ACI-318
5.11 — Curing
5.11.1 — Concrete (other than high-early-strength)
shall be maintained above 50 F and in a moist condition
for at least the first 7 days after placement, except
when cured in accordance with 5.11.3.
5.11.2 — High-early-strength concrete shall be maintained
above 50 F and in a moist condition for at least
the first 3 days, except when cured in accordance with 5.11.3.


In a moist condition? For walls and columns this requirement in the code is routinely if not always ignored. For slabs thy spray on the so-called curing compound but for walls and columns nothing.

Even on cold days (below 40F for 24 hours) the most that is ever done to retain heat in columns and walls is to cram a little fiberglass insulation in the top of the forms.

Why the indifference to there requirements?

 

[Ron]

boffintech...the primary reason for the indifference is lack of enforcement of such provisions. They've gotten away with it for so long, it has become "accepted" not to do it.

 

[boffintech]

The same also in IBC -

IBC 1905.11 Curing.
The curing of concrete shall be in accordance with Sections 1905.11.1 through 1905.11.3.
1905.11.1 Regular.
Concrete (other than high early strength) shall be maintained above 50°F (10°C) and in a moist condition for at least the first seven days after placement, except when cured in accordance with Section 1905.11.3.

IBC Chapter 17 Special Inspections requires periodic "Inspection for maintenance of specified curing temperature and techniques."

Exactly what "curing" methods for walls, columns, etc should be occurring? If nothing occurs for these members should I write this up in a discrepancy report?

 

[henri2]

Walls and columns fall on the category of formed surfaces. As a general rule, the plastic concrete while in the forms, will contain sufficient water for the hydration of cement...similar to curing of grout placed in cells of hollow cmus in masonry construction. However, if the forms are removed prior to the end of the curing period required in the code references you cited, curing methods which add (example wet burlap) or prevent moisture loss should be utilized on the formed surfaces. Exposed unformed surfaces at top of walls should be cured.

I am sure you have a copy of the ICC Concrete Manual. Refer to Sections 17.5-17.8 for more information. Another other useful reference is ACI 308-Guide to Curing Concrete.and for extreme weather conditions, ACI 305 and 306 on Hot and Cold Weather Concreting delves into good practice curing methods. These three ACI documents are included in Part 2 of the ACI Manual of Concrete Practice.

The enforcing jurisdiction's building department should have regulations and guidelines for issues like this because the code does not provided detailed procedures. Example: Fairfax County, VA

https://www.fairfax.va.us/dpwes/publications/simchapter7.pdf

How long does it take to strip forms for walls on the typical project you inspect under weather conditions at this time of year ?

 

[boffintech]

The ICC Concrete Manual has some interesting stuff on curing (chapter 17.5):

"All concrete must be cured."

"Fresh concrete, when placed in the forms, contains more than enough water for combining with the cement during hydration. One function of curing, then, is to preserve or replenish this water for a suitable period of time until the concrete has developed the desired properties. The longer the cure, the better the concrete.”

Then they run through the various curing materials: water, wet coverings, impermeable sheet materials, and sealing compounds.

On jobs that I am on (high and mid rise buildings) walls and columns are formed during the day, concrete is placed in the afternoon, and forms are stripped the following morning.

As near as I can tell no "curing" at all takes place for vertical members. I'll have to check the spec book and see if some specific method of curing is called out for vertical members.

 

[JAE]

We usually specify that formwork can be used as a curing method as long as it is in place for 7 days. If it is removed earlier than that, we require spray on or water-based curing on the exposed concrete.