Contractor Talk - Professional Construction and Remodeling Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1
The mudslab in this picture had the following characteristics:
-3 inch mudslab
-no reinforcement
-Poured in West Michigan in the summer time.
-Placed on subgrade that had passed a test from an independent agency. It was reported, however, that the subgrade was somehwat dry.
-Allowed to cure for about six days.
-Forklifts were driving on it during steel erection.
-80% cement mix

Here is the tricky part. I know a myriad of the reasons I listed could have contributed to issues. The mudslab was supposed to crack, we just wanted it as a base for the actual slab. However, nothing listed would be a legitimate reason for it to totally disintegrate the way it did. I know running forklifts with steel will crack it and I know a dry subgrade will pull the moisture from the mudslab, but we have done this exact same pour tons of times with great results. Does anyone know what this could be?
 

Attachments

·
Registered
Joined
·
5,170 Posts
Without having witnessed the placement of the concrete,it would be conjecture on my end to throw out a cause,many variables . What was the slump,was water added on site,was bleed water present,was it floated or troweled into slab,why was the sub base not dampened,how was it cured,compound,periodic wetting and drying etc.etc.?
 

·
Registered
Joined
·
5 Posts
Discussion Starter #3
It was watered on site. I was not on site either but it seems that the slump was not enough originally and they poured too much water, sending it upward of 6". This was also corrected very quickly from the report. I believed it was actually laser screeded. The big thing about this is it wasn't meant to be a big deal. It was just supposed to be a base instead of pouring the slab on top of the subgrade. We expected deformaties and cracks, but I can't figure out what would cause such disintegration. I was literally picking up chunks and pulling out the river rock (aggregate) as if there wasn't any adhesion whatsoever. I don't think there was a cure.
 

·
Super Moderator
Joined
·
23,773 Posts
Could also be a bad mix. Not enough cement.

Also too much water and dried out too quick.
 

·
Box Builder
Joined
·
6,315 Posts
I'll see less concrete in my life than some of you guys will see in a period of 5 years I'm sure. But that looks like a bad mix. Ive never seen anything like that.
 

·
GC/carpenter
Joined
·
40,965 Posts
Maybe finished too early without allowing proper bleeding? Where the water is suppose to come to the surface. If it's finished too early it can trap water.


Mike.
_________
 

·
Registered
Joined
·
5,170 Posts
Not too be a wise guy after the fact but this is exactly the reason it is always a good idea to fill a test cylinder of every batch delivered. You don't have to send them off for testing unless you encounter a problem such as this.
 
1 - 9 of 9 Posts
Top