Question
We have a brick paver patio that was originally installed in 2001 and expanded/reinstalled in 2005.  We cannot remember if we had it sealed or not in 2005.  In June 2010, we had it powerwashed, resanded (this time with silicon sand) and a herbicide put on it to kill weeds in the cracks.  We now have holes in many of our bricks.  Was this caused by the herbicide?  Or something else?  Is there any way to correct the problem or stop holes in all the bricks?

Answer
I know of only three reasons you could be getting new holes in bricks.
But all depends on what your "bricks" are made of. Are they concrete pavers or are the clay pavers...both commonly called brick.
1. The most likely scenario is that the bricks are possibly reclaimed clay brick from building walls and as such are not "high fired" and therefore not appropriate for ground contact. These bricks are made only for vertical surfaces that do not get thoroughly soaked by water. These bricks soak up water and then freeze in colder weather, the freezing then breaks pieces of the brick's surface off. This is sometimes called "spalling". If you want clay bricks for pavers they have to be fired in very high temperatures and are much more dense. Make sure your pavers were rated fro ground contact.
2. The second option is that there could possibly be a chemical reaction dissolving the brick surface from any number of applied chemicals such as fertilizers or herbicides. But this is not likely.
3. The third option is that the bricks could be faulty. The mix may have been bad and the brick can begin to deteriorate over time. If you have concrete pavers and not clay bricks then this is more likely. If there was too much sand in the mix or not enough of one element or another it is easy for a batch to fail.

My guess is that the first option is most likely as I have never seen a case of a chemical reaction eating small holes in the brick and mix failure is also rare in pavers.
If the first option is the problem, then the bricks will continue to get worse each year.
You may not have noted the problem the first year or two if we did not experience a rain event followed by a freeze in close proximity.


Unfortunately, there is no standard commercially viable way to repair holes in bricks. You may consider sealing the brick with a masonry sealant such as Rez-seal or similar to slowdown the process and keep water out but its is still going to be a problem from the bottom of the brick.

Sorry I don't have better news.

Sean J Murphy
www.seanjmurphy.com