Application Tips

Sharpen Your Skills

You can't overdo the basics. Sometimes it's not the knowledge we lack that causes trouble but the knowledge we forget.

Keeping that thought in mind, we've created a checklist for each of the distinct types of jobs we handle. Before your next project please look it over—and follow through on these fundamental concrete and masonry practices.

CONCRETE
Industrial Floors | Structural Concrete | Functional Concrete

MASONRY
Block | Brick

Concrete Category

Industrial floors

• Verify that the sub-base will support fully loaded ready-mix trucks without causing permanent deflections (1.0" max). Excessive rutting of the sub-base is a visible sign of distress, which will restrain normal floor-slab movements after the concrete is placed. Restraints of any type will create long-term floor cracking problems in industrial settings.
• Hold a pre-pour meeting with the general contractor, concrete contractor, concrete supplier, and a testing agent.
• Make sure the building is weather-tight and properly lighted. High-quality concrete depends on a controlled environment.
• Ensure adequate load transfer over joints.
• Ensure that construction and control joints are protected by rigid joint fillers.
• For more in-depth information on industrial flooring applications, please see the following articles: Why Do On-Grade Slabs Curl, Curling on Concrete Slabs, and How to Use Vapor Barriers under Slabs. Also availiable is a small Flash movie demonstrating the correct method of placement for a vapor-barrier under a concrete slab.

Structural concrete

• Hold pre-pour meetings to cover responsibilities for all participants before and during concrete placement. Meet with the General Contractor, Forming Contractor, Pumping Contractor, Concrete Supplier, Concrete Contractor, Mechanical & Electrical Contractor, and Reinforcing Installer.
• Designate a person to make the call on weather-sensitive concrete placements as well as the deadline for making the call.
• Ensure that all inserts, reinforcements, and embeds are in their proper position before the concrete is placed.

 

Functional concrete

• Make sure the concrete finish is compatible with the intended use of the structure.
• Make sure the mix design is suitable to the application.

Masonry Category

Block – select the proper mortar to use:

• a: Type M: Masony below grade and in contact with earth
  Portland Cement: 1 Hydrated lime: 1/4. Aggregate: not less than 2-1/4 and not more than 3 times the sum of the volumes of the cement and lime used when measured in a damp, loose condition.
  
  
• b. Type N: Medium strength mortar for general use in exposed masonry above grade and exterior masonry walls subject to severe exposure, such as brick.
  Portland Cement: 1 Hydrated lime: 1/2 to 1-1/4. Aggregate: not less than 2-1/4 and not more than 3 times the sum of the volumes of the cement and lime used when measured in a damp, loose condition.
  
  
• c: Type S: Exterior above-grade masonry and interior, load-bearing masonry
  Portland Cement: 1 Hydrated lime: 1/4 to 1/2. Aggregate: not less than 2-1/4 and not more than 3 times the sum of the volumes of the cement and lime used when measured in a damp, loose condition.

 

Brick

• Choose the proper mortar, typically Type N, for brick veneer
• Once the masonry has thoroughly dried, clean it with a commercial cleaning agent; cleaning the brick is a critical step toward preventing stains.

  COMMON BRICK STAINS

  
  White efflorescence

  Cause: Salts dissolved in rainwater, construction water, or ground water. As water evaporates from wet brick, it leaves crystallized salts on the surface.

  Prevention: Protect wall cavities and brick cubes from rain during construction. Let masonry dry before cleaning. Protect the cleaned bricks with an appropriate sealer.

   

  
  Vanadium stain

  Cause: Vanadium-salts dissolved in rain water, construction water, or muriatic acid. As the water evaporates, vanadium salts form on the masonry surface and produce an unsightly stain.

  Prevention: Protect wall cavities and brick cubes from rain during construction. Let masonry dry before cleaning. Protect the cleaned bricks with an appropriate sealer.

   

  
  Brown manganese stain

  Cause: Manganese dioxide dissolved in rainwater, construction water, or muriatic acid. As the water evaporates, manganese reacts with the alkaline mortar joint and creates a brown stain.

  Prevention: Protect wall cavities and brick cubes from rain during construction. Let masonry dry before cleaning. Protect the cleaned bricks with an appropriate sealer.

   

  
  White scum

  Cause: Insufficient pre-wetting or rinsing during cleaning with acid solutions. Mortar dissolved by the acid is absorbed into the wall where it produces silicate salts.

  Prevention: pre-wet and rinse the brick face thoroughly before cleaning it.

   

  
  Acid burn

  Cause: Cleaning with too high a concentration of muriatic acid or other acidic solution. The masonry absorbs the acid and its by-products so quickly they cannot be rinsed out. As the acid attacks both bricks and mortar it brings out salts that create unsightly stains.

  Prevention: Use an appropriate concentration of muriatic acid or other cleaner.

   

  
  Lime run (carbonate staining)

  Cause: Walter collected within a wall dissolves calcium compounds. Over time, the water migrates through openings in the wall surface. As the water evaporates, the dissolved calcium reacts with the atmosphere to produce a calcium-carbonate crust.

  Prevention: Protect wall cavities from rain during construction. Clean bricks with an appropriate cleaner and seal the cleaned bricks.

   

  STAIN REMOVAL

  To learn how to remove these common brick stains, please visit the Prosoco web site.