Problem Clinics | Construction Methods

Construction Methods

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  Demolition Options

  From CC’s LinkedIn discussion group comes this question: Does anyone have another option to remove mass concrete foundations without using an excavator and breaker?

   
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  Bulging Joint Fillers

  Under resilient floors, what is less likely to telegraph joints after moisture equilibration: semirigid epoxy or polyurea?

   
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  Greening of Slag Cement Concrete

  We are using a concrete mix with 60% slag in architectural concrete and are having significant issues with the color of the concrete. What can we do to avoid this?

   
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  What does this moisture test data mean?

  I am employed by a home builder and currently dealing with a homeowner who is claiming moisture damage to the hardwood flooring in her home. She hired a professional who completed the ASTM F2170 test.

   
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  Re-entrant Corner Problems

  We recently were called to apply an epoxy surface to a newly constructed 6-inch-thick warehouse slab with a tight 12x12-foot sawcut control joint pattern. Can you explain what may have caused these random cracks to develop?

   

• Decorative Problem Clinic

  I have been contracted to remove a carpet tile floor and chemically stain the concrete below to provide a decorative finish. When we started removing the carpet tiles, we discovered that some of the adhesive is stuck to the floor. How can we remove the adhesive from the floor to allow the chemical...

   

• Flooring over concrete

  Although I've been lucky so far and have not had to deal with a failure of flooring materials applied over one of my slabs, it scares me to death thinking about it. What can I do to keep this problem from occurring?

   

• Problem Clinic: Air Entrained RCC

  Are air-entraining admixtures necessary to produce frost-resistant roller-compacted concrete pavement (RCC)?

   
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  Problem Clinic, March 2006: Shutting Off the Pump

  The best way to solve your problem is to mount a shut-off valve (also referred to as a guillotine valve) where the pipe enters the form. You can slide the guillotine closed when you are done placing concrete, allowing you to disconnect the pump hose.

   

• Problem Clinic: Removing An Oil Stain

  I am going to glue some fiber reinforced polymer on a concrete beam, but I'm concerned that some oil spilled on the beam may prevent the epoxy glue from adhering well. How can I remove oil that has been spilled on the concrete?

   

• Problem Clinic: Stone, Gravel, or Aggregate?

  I have a specification calling for #89 gravel in the concrete mix and #57 stone for the subbase. What do these numbers mean?

   

• Improving Traction

  The concrete floor in my horse barn has an ulra-smooth finish. I’m concerned that with horseshoes on their hooves, the horses may slip and fall. Any ideas on how to improve the traction?

   

• Fly Ash in Concrete Pavement

  What are the effects of using fly ash in concrete pavements? Does it have an impact on abrasion resistance of the mix? Are case studies or field data available, especially where more than 30% fly ash was used in the mix?

   

• Is It the Slab's Fault?

  A flooring contractor has experienced problems on four occasions over the years with his two-part polyurethane floor covering not bonding to our concrete slab-on-grade. He has said that the acid-etch process prior to installing the covering did not react

   

• SCC for Piles

  We are considering using self-consolidating concrete in bored cast-in-place piles up to 20-m deep. How can we check the level of compaction? Are there clear specifications for testing SCC and test specimens preparation? We cannot locate any ASTM or similar standards or material and workmanship...

   

• Misdirected FF numbers?

  We recently placed a concrete floor with a laser screed. The floor had an FF requirement of 35 and an FL of 30.

   

• Settling In

  Before we purchased our home, part of the foundation under the house dropped approximately 4 inches. At that time the owner hired a contractor to fix the problem. By digging down alongside and putting jacks under the foundation, the contractor raised the level of the home to its proper elevation...

   

• Cracks at the Ends of Sawed Joints

  When we saw contraction joints for slabs placed when walls are already in place, we have to end the cut 2 to 4 inches from each wall, depending on the saw-blade diameter. The crack that forms at the end--as a continuation of the cut--is never straight. Is there any way to saw joints all the way to...

   

• Acceptable Curling

  Are there any standards for an acceptable amount of curling for a concrete floor slab?

   

• Does Concrete Absorb Adhesive Moisture?

  We're the general contractor for a commercial building in which the concrete floor will receive a moisture-sensitive covering. The floor-covering manufacturer requires a maximum water-vapor emission rate of 3 pounds/1,000 square feet/24 hours. Before applying the floor covering, we plan to wait...