×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

MASONRY RETAINING WALL - HOW LONG BEFORE BACKFILLING
2

MASONRY RETAINING WALL - HOW LONG BEFORE BACKFILLING

MASONRY RETAINING WALL - HOW LONG BEFORE BACKFILLING

(OP)
I am designing a 3 ft high bar reinforced 8" masonry wall, with depth in the ground also 3 ft, all on a reinforced concrete footing.
How long should I allow for masonry curing before back filling? - I want to put this in notes. No cylinders or cubes will be taken to review reports.

RE: MASONRY RETAINING WALL - HOW LONG BEFORE BACKFILLING

With no samples being taken I would say you can only rely on the nominal time to develop the specified strength of the grout fill. In this part of the world concrete strengths are based on 28 day strengths. We all know the time to develop the 28 day strength would be considerably faster than this as concrete suppliers have to be sure to hit the lower characteristic strength at this point in time. So most mixes develop a considerably higher strength over time.

In my experience usually within 2 weeks you hit the 28 day value, but it can vary a week either way depending on the mix design and environmental conditions. Only way to know for sure is to take some cylinders.

The concrete supplier may have historic data on the mix from testing within the batching plant which might offer some guidance with respect to the time.

Additionally I have seen some people specify for example that walls may be backfilled when 75% of the nominal strength of the grout is attained, over to the contractor as to how he determines this.



RE: MASONRY RETAINING WALL - HOW LONG BEFORE BACKFILLING

Since this is close to being a typical gravity retaining wall at only 3 feet high in front, it probably doesn't make any difference as to when you backfill. A typical gravity retaining wall has a thickness of 1/3 the height, and can be made out of material not significantly strong, such as rocks laid up without any grout. It's a judgement case and, to be more sure, just don't compact in back within 2 feet of the wall above outside grade elevation. Compacting early on up to outside grade elev. (front and back) will help in the curing process.

RE: MASONRY RETAINING WALL - HOW LONG BEFORE BACKFILLING

7 days preferred. 3 days minimum if they scream and holler and need to keep moving on the project.
But in neither case allow wheel or other loads above the wall closer than 5 feet.



Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: MASONRY RETAINING WALL - HOW LONG BEFORE BACKFILLING

At only three feet high, chances are that you have minimum steel in the wall and are nowhere near the moment capacity of the reinforcing with the backfill you mention. Three to four days should be fine here, but do keep the wheel loads and vibrating compactors away for 7 days minimum.

Mike McCann, PE, SE (WA)


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources