Concrete ASR/freeze-thaw question
Concrete ASR/freeze-thaw question
(OP)
I am looking for some assistance with understanding ASR and freeze-thaw damage. I have concrete cores and petrographic analysis for the structure described below and I'm trying to make a recommendation for repair/replacement based on the results. I'm trying to determine the cause of the cracking in order to make a recommendation.
The structure is a concrete pier at a dam. The pier is roughly 10'Wx30'Lx35'H with non-airentrained concrete. 10' deep vertical core was taken along longitudinal centerline and about 3' from nose of pier. The core was reported as being "extensively fractured" and broken into 5 separate pieces. Petrographic analysis was done and distress was reported as being caused by a combination of ASR and freeze-thaw damage. In the photos of the cores I see both diagonal and horizontal cracking. Structure was built in early 1940's and is located in the northeast. The piers support a concrete deck and gantry cranes used for lifting gates.
I'm thinking the cracking deep within the structure is likely due to freeze-thaw and not the ASR as I have read that it is rare for alkali-aggregate reactions to be the cause of cracking. Am I off base here? Can the breaks in the core be caused by ASR? Any suggestions for repair methods I can research? My initial thought was remove and replace. Is it possible to pin the pier somehow? Someone at work suggested I look into a polymer wrap (because of the ASR) but I thought that was more of a surface repair and was concerned that it might add thickness to the pier (which could interfere with gate movement).
I appreciate any help.
The structure is a concrete pier at a dam. The pier is roughly 10'Wx30'Lx35'H with non-airentrained concrete. 10' deep vertical core was taken along longitudinal centerline and about 3' from nose of pier. The core was reported as being "extensively fractured" and broken into 5 separate pieces. Petrographic analysis was done and distress was reported as being caused by a combination of ASR and freeze-thaw damage. In the photos of the cores I see both diagonal and horizontal cracking. Structure was built in early 1940's and is located in the northeast. The piers support a concrete deck and gantry cranes used for lifting gates.
I'm thinking the cracking deep within the structure is likely due to freeze-thaw and not the ASR as I have read that it is rare for alkali-aggregate reactions to be the cause of cracking. Am I off base here? Can the breaks in the core be caused by ASR? Any suggestions for repair methods I can research? My initial thought was remove and replace. Is it possible to pin the pier somehow? Someone at work suggested I look into a polymer wrap (because of the ASR) but I thought that was more of a surface repair and was concerned that it might add thickness to the pier (which could interfere with gate movement).
I appreciate any help.






RE: Concrete ASR/freeze-thaw question
If you go this route, and your water level varies as well, be prepared for the area of unsound concrete to extend over the entire wet/dry zone.
RE: Concrete ASR/freeze-thaw question
RE: Concrete ASR/freeze-thaw question
ASR; however, can be insidious and can do damage at any level in the concrete as long as the reactants are there. The speed of the reaction is generally influenced by water availability, but will ultimately occur even at low moisture contents in the concrete.
Without looking at the concrete samples and the particle sizes being affected by the ASR, I cannot make a true assessment, but I would be more inclined to look toward ASR for such described damage rather than freeze-thaw.
RE: Concrete ASR/freeze-thaw question
RE: Concrete ASR/freeze-thaw question
RE: Concrete ASR/freeze-thaw question
Could the problem be thermal from the mass concrete? Were there thermocouples installed at the time? not likely common for 70 year old concrete. Were the 'fractures' caused by cold joints?
Just some thoughts... Dik