Slab Problems

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    Expansion Joints

    Are expansion joints necessary?

  • Removing Burlap Stains

    For a concrete plaza surrounding a large sculpture, the engineer specified a wet cure. The contractor used burlap to keep the concrete wet while it cured, but the burlap left some ugly stains. Can you recommend a way for us to get rid of the stains?

  • Spalling in Parking Lots

    What causes spalling in concrete parking lots?

  • Concrete Expansion Joints

    Are joints in concrete meant to accommodate expansion or contraction? Someone told me that what I've always called expansion joints I should now call contraction joints. Does this mean that concrete doesn't expand? What are these joints actually supposed to do?

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    The Importance of Reading Blueprints

    In Part 1 of our series on the importance of being able to read contract specifications, we look at reading blueprints.

  • SCC in Tilt-Up Applications

    Q: Can self-consolidating concrete be used for tilt-up panels? What does the finish look like, and are plastic shrinkage cracks a problem?

  • The Ideal Concrete Surface for a Hospital

    Q: We have a hospital expansion project and are considering polished concrete as the flooring material throughout. Our issue on this project is moisture (about 92% internal relative humidity after eight months), so the sheet vinyl originally installed has

  • Repair Spalling With an Overlay

    My brother has a large driveway and parking area in front of his house in eastern Washington state. The concrete surface is spalling, possibly from overuse of deicers. The concrete is a minimum of 6 inches thick with rebar. The concrete is structurally

  • Biting the Dust

    The owner of a recently constructed manufacturing facility contacted us to help solve a problem with the concrete floor's surface.

  • Grinding Questions From a Novice

    I am the building manager for a large church on the East Coast. We recently have contracted with a company to grind and overlay about 5000 square feet of our church.

  • Did Salt Finish Affect Color?

    I am the building manager for a large church on the East Coast. We recently have contracted with a company to grind and overlay about 5000 square feet of our church.

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    Problem Clinic: Why Does Concrete Discolor?

    Why does concrete discolor even though the specifications (wet cure) were followed without exception?

  • What Caused This Scaling?

    I have an issue with a customer about her sidewalk surface spalling. She called me in February saying it was popping off in pieces. The sidewalk was placed about seven months earlier in June of the previous year. I am sure she is salting the sidewalk and

  • What Caused This Scaling?

    Home builders here in the Denver area recently have had a rash of scaling driveways. Literally hundreds of driveways constructed over the past two to four years are showing isolated to widespread scaling. Our firm and others have met with the builders to

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    I am bidding on treating a concrete slab and one of the specified requirements is that there not be any birdbaths. The final surface will be flooded to see if this has been achieved. Do you have any suggestions?

  • How Curling Happens and How to Control It

    I am about to install a 10,000-square-foot floor and the owner believes that wet curing the floor will result in no curling. Is this true?

  • More On Adjusting for Aggregate Moisture

    We had a long dry spell this spring followed by several days with short but intense rainfall. That seems to cause inconsistency in the concrete we're getting from our producer. Why does a little rain make things so difficult?

  • On the Questionable, and Perhaps Lost, Art of Curing Concrete

    I have a project specification that requires fog spraying, followed by curing compound, followed by wet cure with burlap and soaker hoses. Why the complicated curing requirements? Isn't this a case of specification-overkill?

  • Concrete Expansion Joints

    I was told that what we used to call expansion joints I should now call contraction joints. Does that mean that concrete doesn't expand?

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    From Shrinkage to Shadowing

    We've been asked to bid on a polishing project on a recently placed slab. The engineer had been concerned about controlling concrete drying shrinkage. He developed a concrete mix design optimization plan that resolved many of the problems that occur on industrial slabs on ground. The slab has...


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