NACE CIP 2 Study Guide
Name and define the three NACE standards classifications.
Correct Answer:
-SP: Standard Practice
- TM: Test Method
- MR: Materials Requirement
Acid Etching
Correct Answer:
This process uses a dilute acid solution to remove laitance and roughen the concrete surface.
Efflorescence
Correct Answer:
This condition is caused by moisture passing through the concrete and carrying soluble concrete salts with it to the surface. The salts react with carbon dioxide in the atmosphere, creating a fluffy white crystalline deposit on the surface.
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Low-Pressure Water Cleaning (LP WC)
Correct Answer:
Water cleaning performed at pressures less than 34 MPa (5,000 psig). This is also called "power washing" or "pressure washing".
Laitance
Correct Answer:
Weak surface layer of water-rich cement mixture of fresh concrete caused by upward movement of water.
Some of the properties of concrete are:
Correct Answer:
- Extremely durable
- Inorganic
- Hard
- Has good comprehensive strength
- Improves with age
What is the process by which concrete cures?
Correct Answer:
Hydration
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How do ambient conditions and vibration affect poured concrete?
Correct Answer:
- Ambient conditions: Hot weather causes concrete to cure more rapidly than otherwise,
resulting in a greater possibility for voids, and a dusty, low-strength surface. Applying a curing compound can help mitigate the effects of these conditions. Many entities require a wet burlap curing blanket to be used over freshly placed concrete to prevent this type of "drying out".
- Vibration: This is done to remove air pockets, and can cause the heavy aggregate to
sink to the bottom of the form. This results in a weak, sandy surface, creating a fragile layer of sand cement known as laitance. This condition can occur both at the upper surface and at the concrete/form surface or interface.
Explain Guniting.
Correct Answer:
The process of spraying or slinging shotcrete ono a surface as a coating to restore concrete to its original grade.
Concrete may be coated for several reasons including:
Correct Answer:
- Decoration
- Waterproofing
- Enhancing chemical resistance
- Protection from freeze-thaw cycles
- Protection of reinforcing steel
- Decontamination 3 / 4
- Surface sealer
- Protection against abrasion and erosion
- Color coding
- Protecting purity of water or other products contained
- Improving and simplifying cleaning
- Skid resistance
Describe the difference between laitance and efflorescence.
Correct Answer:
- Laitance is a weak surface layer of water-rich cement mixture on the surface of fresh
concrete caused by the upward movement of water.
- Efflorescence is caused by moisture passing through the concrete and carrying soluble
concrete salts with it to the surface. The salts react with carbon dioxide in the atmosphere creating a fluffy white crystalline deposit on the surface.
Surface preparation is generally performed on concrete by:
Correct Answer:
- Abrasive blast cleaning
- Hand and power tool cleaning
- High-pressure waterjetting or blasting
- Acid etching
- Stoning
- Centrifugal blasting
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