Bridgegirl67
Structural
- Sep 11, 2009
- 14
Contractor is blind pouring a concrete tunnel liner (un-reinforced) in approximate 40' sections. It is a 24' diameter (finished diameter) and walls are a minimum of 18" thick (greater in a majority of the locations).
NOTE: There is almost no water infiltration into the tunnel and any that is coming in, is infiltrating from areas beyond the pour.
Contractor is working on forming the 6th pour. We have found a couple locations in the invert of the concrete tunnel in a couple of the previous pours where the concrete is soft. Essentially we can dig into the concrete with a hammer 7+ days after the pour and the 3 day strength tests are coming back at anywhere between 3,800 to 5,600 psi. The areas are isolated (not the full length of the pour) but occur in the invert at the locations discovered to date.
Any ideas as to the cause (how we can limit or prevent this)?
In addition, anyone have experience with how something like this has been repaired in the past. As of right now we are looking at a full depth removal repair.
Thank you in advance.
NOTE: There is almost no water infiltration into the tunnel and any that is coming in, is infiltrating from areas beyond the pour.
Contractor is working on forming the 6th pour. We have found a couple locations in the invert of the concrete tunnel in a couple of the previous pours where the concrete is soft. Essentially we can dig into the concrete with a hammer 7+ days after the pour and the 3 day strength tests are coming back at anywhere between 3,800 to 5,600 psi. The areas are isolated (not the full length of the pour) but occur in the invert at the locations discovered to date.
Any ideas as to the cause (how we can limit or prevent this)?
In addition, anyone have experience with how something like this has been repaired in the past. As of right now we are looking at a full depth removal repair.
Thank you in advance.