Pressure washing concrete


New member
Just started pressure washing as a side gig but would like for it to one day become a full time opportunity. I pressure washed this concrete driveway today. Once I finished the job I noticed these random dark spots that were on the concrete. The driveway was completely dry. The concrete is 20 years old. Was this an error on my part or just the aging from the concrete over the years?? Thanks in advance. Here are some after pics
It looks pretty good for a 20-year-old concrete, to be honest. I had a similar issue with our previous driveway. No matter how much I washed it and what solutions I tried, it still wasn't perfectly clean, and the cracks were all black. The only solution I found was calling commercial concrete contractors Denver CO, and asking them to rebuild it. It might have been an impulsive decision, but I didn't regret it for a second. It's an absolute pleasure seeing that perfect driveway every morning.
I’ve seen some guys cleaning such concrete. Really impressive. But I think the initial problem is all about making this concrete. I think I should show this pic to my friend from He knows literally everything about concrete, so he may tell us the main cause of this. Actually, my neighbors have the same concrete issue. But I guess concrete is still better than asphalt, which requires annual maintenance. Btw, what do you think of asphalt? Wouldn’t it be better if the US had more asphalt roads?
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