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See also Gypsum Accelerator & Retarder

  FAST CAST™ Exterior Gypsum Cement

Fast Cast Fastcast

 

Click here for MSDS.

A High-Performance Time Saving Solution for Your Exterior Casting Needs.

  • Rapid setting cementitious material when used with sand aggregate.
  • Quick demolding capability increases productivity 300% over conventional cements.
  • Excellent resilience and chip resistance.
  • Ideal for free standing, exterior casting, and decorative figurines.
  • Grey in color.
Technical Properties English Metric
Use Consistency (parts of water by weight per 100 parts Fast Cast and Sand) 12.5 12.5
1 Hr. Compressive Strength 2,500 psi 17.2 MN/m2
Dry Compressive Strength 8,000 psi 55.2 MN/m2
Maximum Setting Expansion 0.10% 0.10%
Density
Wet 131.0 lb/ft3 2.10 g/cm3
Dry 110.0 lb/ft3 1.76 g/cm3
Set Time* 25-35 min. 25-35 min.
*Other set times may also be available. Call your sales representative for more information.
 
General Directions and Guidelines

  Required Mix Design

50 lbs. Fast Cast Exterior Gypsum Cement
50 lbs. sand (fine aggregate)
1-1/2 gallons (U. S.) water (12.5 pounds) (Water measurement may have to be adjusted slightly for particle size and water content of sand. Refer to IG779 Technical Bulletin for details.)

Sand should be clean, dry, pre-washed, and properly-sized. It should be free from dolomitic and aluminum contamination and conform to ASTM C33 (see graph below). An example of a suitable commercially available sand is All Purpose Sand. Fast Cast Exterior Gypsum Cement must be used with sand to maximize durability. For specific recommendations, consult your local United States Gypsum Company Technical Sales Representative or call (800) 487-4431

 
 
  Mechanical Mortar
Mix Procedures
  1. With the mixer operating, add half of the sand to the water.
  2. Carefully strew or sift the Fast Cast Exterior Gypsum Cement into the mixer. Do not soak.
  3. With the mixer operating, carefully add the remainder of the sand.
  4. Mix thoroughly until lump free and slurry becomes pourableÑ3 to 4 minutes, but no more than 5 minutes.
  5. Carefully pour the slurry into the mold to prevent entrapped air. Agitate the filled mold to assist in removing any noticeable air bubbles.
  6. Set time is 25-35 minutes. Allow casts to remain in the mold for approximately one hour after set to ensure the adequate green strength necessary for demolding.
  7. Demold and transfer the cast to a suitable drying area. Bench dry the castings to a constant weight before packaging for shipment. If the drying time must be accelerated, castings can be placed in a drying room capable of producing both increased air circulation and drying temperatures. Maximum temperature in a drying room should not exceed 120°F. Consult your United States Gypsum Company Technical Sales Representative for recommendations.
 
  Mechanical Mixing - Variable
Speed Propeller Type Mixer
  1. Add the sand to the water.
  2. Carefully strew or sift the Fast Cast Exterior Gypsum Cement into the mixing container. Do not soak.
  3. Use a high-speed, variable-drive propeller mixer to disperse the slurry. Mix for 3 to 4 minutes, but no more than 5 minutes.
  4. Mix thoroughly until lump free and slurry becomes pourable - 3 to 4 minutes, but no more than 5 minutes.
  5. Carefully pour the slurry into the mold to prevent entrapped air. Agitate the filled mold to assist in removing any noticeable air bubbles.
  6. Set time is 25-35 minutes. Allow casts to remain in the mold for approximately one hour after set to ensure the adequate green strength necessary for demolding.
  7. Demold and transfer the cast to a suitable drying area. Bench dry the castings to a constant weight before packaging for shipment. If the drying time must be accelerated, castings can be placed in a drying room capable of producing both increased air circulation and drying temperatures.
    Maximum temperature in a drying room should not exceed 120°F. Consult your United States Gypsum Company Technical Sales Representative for recommendations.
 
  Precautions
  1. Water purity is important. Water should be as pure as possible. Typically, if water is drinkable, it is probably suitable for mixing the product. Water contaminated with organic impurities, soluble salts, and other chemicals may cause detrimental effects to Fast Cast Exterior Gypsum Cement.
  2. Proper mixing ensures dispersion of the Fast Cast Exterior Gypsum Cement powder into the water. Accurately weighed water, powder, and sand is necessary to assist in fabrication of quality castings. Refer to required mix design for proper amount of mixing water.
  3. Timing mix cycles is essential. Mechanical mixing methods must be used. Do not mix by hand.
  4. Pour pieces in one continuous pour.
  5. Fast Cast Exterior Gypsum Cement is not a suitable product for the fabrication of bird baths, water fountains, or other applications where constant exposure to water occurs; nor is it suitable for casting planters or flower potting containers.
  6. Fast Cast Exterior Gypsum Cement is not suitable for structural or non-structural exterior architectural applications.
  7. Do not use Fast Cast Exterior Gypsum Cement for below grade applications.
  8. Do not use sealers or coatings on Fast Cast Exterior Gypsum Cement pieces.
  9. Do not use aggregate that does not meet the size requirements of ASTM C33.
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Although we try to keep the most updated prices on our website, all prices are subject to change.
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