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


Sulfuric Acid Attacks Concrete

Sulfuric Acid Attacks Concrete

Sulfuric Acid Attacks Concrete

Does the concrete expand when sulfuric acid come in contact with the concrete? I have this secondary containment concrete trench with an acid proof lining. The lining was compromised over the years and now the sulfuric acid had worked its way to the bottom portion of the concrete trench wall on both sides. I can actually easily scour the said area with a hammer claw since it is very soft and damp. We will take a sample in the soft area and test for PH level.  Expect the sample to be way below 7.

Any help will be appreciated.    

RE: Sulfuric Acid Attacks Concrete

I'm sure there is some expansion from the attack on the cement matrix. But what's the difference?  The sulfuric acid has damaged the concrete.  Take out the bad concrete, repair and recoat it.

RE: Sulfuric Acid Attacks Concrete

Concrete is susceptible to acid attack because of its alkaline nature. The alkaline components of the cement paste (calcium hydroxide) break down with acid exposure.

 H2SO4 + Ca(OH)2 -> CaSO4 + 2 H2O
Sulphuric acid is very damaging as it combines an acid attack and a sulfate attack.

The reaction between sulfuric acid and the calcium compound in concrete will form calcium salts, which are soluble in water. These water soluble salts leach away, causing a loss of volume and cohesion of the cement paste  

RE: Sulfuric Acid Attacks Concrete

The concrete will not expand under sulfuric acid attack or exposure.  It will disintegrate until the reaction is consumed, which could affect just the surface or could go through the concrete section depending on the amount and concentration of the acid.

The reaction that bimr noted is the typically the first and most significant, though sulfuric acid also reacts with the alumina compounds and others.

RE: Sulfuric Acid Attacks Concrete

For the repairs, suggested above, consider using Type V cement in the concrete. It has high inherent sulfate resistance, but is sometimes difficult to obtain. There are other ways to improve sulfate resistance if Type V cement is not available, see:

However, NONE of these products are a substitute for a proper "acid proof" lining, just another step that may be taken.  What you describe is classic deterioration that happens in water treatment areas of industrial plants.

www.SlideRuleEra.net idea
www.VacuumTubeEra.net r2d2

RE: Sulfuric Acid Attacks Concrete

Thank you all for your answers. I have provided a sketch and photos of the trench to see if you can be able to help me answer why the trench wall is moving upward. I am not sure if the acid attack on the lower walls are causing all these concrete cracks or is it the soil around the trench although the soil looks good to me. Notice the discolaration on the bottom of the trench walls. This is where the soft spot as indicated in my sketch.

RE: Sulfuric Acid Attacks Concrete

Opps-disregard the photos.

The type of concrete we will use is from Sauereisen-Epoxy Novolak Polymer Concrete No. 265. This supposed to resist a wide range of solvents, oils, acids and acid salts (except hydrofluoric) over a pH range of 0.0 t 14.0. Maximum service temperature of 180 def F and low porosity.

RE: Sulfuric Acid Attacks Concrete

I believe hydrated calcium sulphate is in effect "gypsum" (of maybe similar soft consistency as you are describing gouging with a claw hammer?)  While I don't know about swelling of corroded concrete per se, if there is any steel mesh or other reinforcement in the concrete I have heard that will indeed swell if corroded (per some authorities I've heard maybe up to 3-8 times its original steel volume).  [While I guess "acid proof" are efective marketing words, from an Engineering standpoint (and particularly for concrete coatings) that may be a pretty tall order for any material!]     

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!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close