problems w/concrete

[Fairway]

We washed some newer concrete---9 months old, and a grey silty grit seemed to wash off the surface. Also, when washing no matter how many times we passed over the surface there were many overlap marks and just an overall very inconsistant look. It seems to be something to do with the concrete being soft(all the silt washing from the surface) but this has only happened maybe one other time and I wanted to see how common this is, and see if there are any fixes. Thanks

Also - we did use a surface cleaner

 

[the_GUNN_man]

With new concrete you get a cream like cover over it from when you bull float it and it draws the water to the surface. When you wash it with high psi you start to wash it away. That is usually where you get the silty stuff you talk about from. Another thing, did they brush the concrete or was it smooth? They usually brush driveways and sidewalks to give them traction in slippery conditions. When you use your surface cleaner how far do you overlap? I never have many problems with overlap marks with my surface cleaner. I did when I used to try and use a wand. How much psi did you use on the concrete? On my surface cleaner I can adjust the height of the bars. I like that so if it starts digging into the concrete too much I can back off. I am not an expert on concrete but I am sure there are others here who will have some helpful info for you.

 

[Clean County]

Its rare but every now and then I run across concrete that seems to be not as durable as most other concrete. This is probably due to when they mixed the concrete they shorted it somewhere. Its called Shotty work because Concrete should be a lot more durable then what your explaining.

Just be careful when dealing with this type of concrete because you can scar the hell out of it. Companies that put down concrete like this probably I what we call LOWBALLERS. There charge is cheaper then most and they put down just that...Cheap/undurable concrete which will probably crack and have other problems in the not so near future.

 

[Mikespowrwash]

Just a thought, sometimes not often but sometimes the concrete manufactuerer makes a mistake in the mix. Ive oredered 3500 mix and the mix they sent had way too much sand making the product weaker. Ive worked with concrete for almost 15 years. 9 months is too green to use high psi. A light cleaner and warm to hot water with more flow and less psi would be the way to go on new concrete. If the mix was wet when they poured it the cream came to the top and all the stone went down into the concrete deeper. This concrete will be more likely to experience surface problems such as you described in your post. May want to sell a sealer job on this one to help protect it and make it easy to clean in the future. About the overlap marks, are they very noticeable? If not too noticeable don't do anything if they are bad you may want to use a very light acid cleaner and rinse with your wand with low psi and higher volume.

 

[Fairway]

thanks for the replies.