This is from concrete in Northern California that was poured about 5 years ago. Client sent me this picture and asked if it can be removed / what it is.
Does anyone have any ideas what it might be? He says they’re random and all over the place. Doesn’t really look organic to me so I thought I’d ask here.
Thanks!
Did the client just notice it or has it been there since it was poured?
Its been their for a while, but he thinks its a more recent development.
It was likely present not long after the slab was poured, but it has become more noticeable over time as the surrounding surface accumulated dirt and weathering. The pattern is consistent with mineral or moisture-related discoloration that can occur during curing, often when moisture or groundwater migrates upward and carries fine particles or minerals to the surface. Cleaning the area will likely help it blend in, as the contrast should be less noticeable. You may want to look into acid washing as an option, but since the discoloration may be below the surface, it may have limited effectiveness and could potentially make the appearance worse rather than better.
Look for garden gnomes in the yard, looks like gnome pee. 
@OhioFloMo gave you a pretty good breakdown of some possibilities. So many variables. Could be metal rusting in the crete too. Concrete is porous, not the solid thing most people think it is.
