×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Coloring vs. Staining Concrete
2

Coloring vs. Staining Concrete

Coloring vs. Staining Concrete

(OP)
I have a project involving a bridge replacement in which the USFS is requiring us (Public Works) to design the bridge to meet specific "scenic objectives". Basically they do not want a normal grey concrete bridge, they want it to somewhat blend into the forest scenery. I have contacted a few concrete contractors in the area and have been given conflicting statements on staining vs. coloring both cast in place structures and precast structures. One says staining requires more maintenance (seal eavery couple of years), while another says using stain is more permanent and not as maintenance heavy as the other stated.

So looking at both initial costs and maintenance costs, (we of course prefer the less maintenance aspect) would coloring be the better route? And does staining really require the maintenance of sealing every couple of years? Has anyone experienced a similar situation? Any input would be greatly appreciated!

RE: Coloring vs. Staining Concrete

2
Does the bridge have just one type or two types (precast or cast in place)or is the exposed area of concern all the same type?

Are the local ready-mix suppliers capable and experienced with pigmented concrete? I assume a precaster has the experience and quality controls.

If you lump "staining" into one category, you are getting a wide range of products and processes. You may want to also research the stain suppliers instead of concrete contractors, since they usually have a wide range od applications under many conditions.

Dick

RE: Coloring vs. Staining Concrete

(OP)
Thanks for the response, Dick.

The bridge will have cast in place abutments (3) and precast girders (2 spans).

I have a feeling the local redimix suppliers are capable, but not as experienced (small market area).

In your opinion, would using colored mix provide a better controlled result?

Steve

RE: Coloring vs. Staining Concrete

Look at the bridges around the Las Vegas loop.  Cement based paint used on recessed patterned concrete with 25 year life.

RE: Coloring vs. Staining Concrete

(OP)
The paint would be an issue environmentally speaking. I don't think Vegas has the wetland/endangered fish supporting creeks worries this project is facing. As it is, looks like we're going to have to stage 3 cranes in the wetlands just to set the girders. So staining/dyeing prior to placement is preferred.   

RE: Coloring vs. Staining Concrete

the color of the precast will not match the cast in place color if using a dye mixed into the concrete. It is best to have all concrete with color dye produced at the same time by the same plant in order to best match the resulting color.  staining would probably produce a better color match.  However, you will have to stain your abutments in-place which will have the same, if not additional impacts on the fish as the paint.  My experience with stains, is that surface prep is essential to obtaining a uniform result and the same prep needs to be done on both the precast girders and on the abutments.  this will probably require an acid etch on the abutments which will impact your stream also.  I think pain has the least impact and greatest chance of matching.

RE: Coloring vs. Staining Concrete

"dyes" should not be used to tint concrete.

In the international and domestic concrete industry, synthetic iron oxides are the most commonly used materials, especially in the range of colors usually desired and where ultra violet resistance is needed. They are readily available 1000's of yellows, reds, tans, browns and even in some blacks in addition to blended combinations. They warm the cold gray color of concrete. Normally, the sythetic (refined and processed) iron oxides are have the strongest tintin strength and are more consistant. The natural oxides and "umbers" are weaker and contain more imputities. For synthetic iron oxides, the maximum dosage is 10% of the cement content, with the average in the range of 1/2 to 3%.

For some other colors, there are other oxides (chrome as an example), but they are very strong and are for non-traditional tints.

Other types of "dyes" are better suited for other applications and uses. For practical opinions, I would think the producters of "tinted/colored" concrete and concrete products and the pigment suppliers (Bayer Chemical, Pfizer, Rockwell, and following entities) should be contacted in addition to local concrete contractor. The material suppliers and the producers have a much wider range of experience and the expertise, technical research and background in both factory produced and site cast concrete products)and it is a large part of their business.

Dick

RE: Coloring vs. Staining Concrete

Oxide in the concrete, as Dick recommends, is the best solution.  I would avoid just staining the surface.  Any surface application will require maintenance.  

RE: Coloring vs. Staining Concrete

The problem with oxide in the concrete is that it can get quite expensive to colour the whole body of the concrete. Precasters sometimes add oxide just to the top layer but that affects the casting process and the moulds. You can do it by having a coloured batch which you spread in the mould say 100m thick and then another plain batch which goes in on top. Quite difficult to control though. Staining is usually done with acid which etches in the colour and as others have pointed out that can have environmental implications when the acid is washed off. Though if you are precasting then this could be done at the factory. The other option is to render with an oxide pigmented render. That would be maintenance free too. The other thing to investigate would be using lime oxide paint. It's basically a lime wash (whitewash) with oxide added in. It is very durable and much cheaper than synthetic paints. They could even be lime washed at the precasters yard. It doesn't give you a really even finish but it can look much more natural than synthetic paints and might fit in well.

Carl Bauer
www.bauerconsultbotswana.com

RE: Coloring vs. Staining Concrete

(OP)
Thank you all for your comments/suggestions. Oxides are looking to be the front runner at this point, if the project goes forward.

RE: Coloring vs. Staining Concrete

We don't allow anything other than colored concrete.  Quality control in the long run (usually after the contractor is gone) turns into a major issue.  If you are concerned with the long term appearance, the color must be full depth.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources