This document covers two mix designs for lightweight concrete that may be used as floorfills. For further information, please see Redco's Product Information Bulletin #203b.
Lightweight concrete floors for sound control in wood frame construction have proved their effectiveness for many years. Excellent sound deadening lightweight concrete can be installed without special foaming equipment, from materials readily available at all building material dealers. For smaller jobs, materials can be job mixed and placed by any type of plaster or grout pump.
One common mix that will place and finish easily is as follows:
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| Plastic Cement | 2 Sacks |
| RedcoLite Plaster or Concrete Aggregate | 3 Cu.Ft. |
| Plaster or Concrete Sand | 4 Cu.Ft. (28-30 Shovels) |
| Water | 16-18 gallons |
This concrete will have a dry density of about 90 pounds per cubic foot with a compressive strength of 1200 - 1500 psi (Hard rock concrete weighs 140 - 150 pounds per cubic feet). Yield of this batch will be 7 to 8 cubic feet, or 50 to 60 square feet laid to the thickness of a 2x4 plate (1½ inches).
For Retrofit applications (where a maximum of 70 lbs per cubic foot dry density is permissible), the following mix is suggested:
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| Plastic or Common Cement | 1 bag |
| RedcoLite Plaster or Concrete Aggregate | 2 Cu.Ft. |
| Polypropylene Fiber (15 denier, 3/8" long) | 1½ Lbs |
| Water | 5-6 gallons |
This mix will have a dry density of about 60 pounds per cubic foot, with a compressive strength of 1,800 - 2,000 psi. This mix should be placed a minimum of 1½" thick; and 30 minutes prior to pouring, a latex bonding agent should be used between the wood/felt and the concrete. Yield of this mix will be approximately 1¾ cubic feet, or 18 board feet (twelve square feet laid at a thickness of 1½").
Mixing instructions: For either mix, place required water in the mixer (a small amount may be withheld to the end of the mixing cycle to avoid excess water). Add the cement and mix until the slurry is uniform, approximately 1 minute; then add the perlite and the fiber, if appropriate. Mix until thoroughly blended, usually from 1½ to 2 minutes, but not longer then 4 minutes. Over-mixing can result in unnecessary loss of yield.