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Structural Lightweight Concrete

Structural lightweight concrete made with Buildex aggregate solves weight and durability problems in buildings and exposed structures. Buildex concrete has strengths comparable to normal weight concrete, yet is typically 25% to 35% lighter. Buildex offers design flexibility and substantial cost savings by providing less dead load, improved seismic structural response, longer spans, better fire ratings, thinner sections, decreased story height, smaller size structural members, less reinforcing steel, and lower foundation costs. The excellent durability performance of Buildex is a result of the ceramic nature of the aggregate and its exceptional bond to, and elastic compatibility with, the cementitious matrix.

Guide Specification (Short Form): Sec 03300:

Materials:
Expanded shale lightweight coarse aggregate shall be Buildex or approved equal, manufactured by the rotary kiln process, and shall meet ASTM C 330. Grading shall be 1/2" x No. 4 as detailed in C 330. Coarse lightweight aggregate shall be pre-wetted prior to mixing if placement is to be made using a concrete pump. Follow the lightweight aggregate manufacturer's recommendations for pre-wetting procedures. Normal weight fine aggregate shall meet ASTM C 33.

Concrete Properties:
Strength:
Proportion materials to produce concrete with a minimum compressive strength of __ psi at 28 days.

Comment: Commonly specified compressive strengths are 3000 psi and 4000 psi, but higher strengths, up to 9000 psi, are attainable with special mixes.

Unit Weight: Proportion materials to produce concrete with a 28 day air dry unit weight of 107 to 113 lb/cu ft, as determined by ASTM C 567 "Test Method for Unit Weight of Structural Lightweight Concrete".

Comment: The fresh, pumped in place unit weight of this concrete will be approximately 116.5 lb/cu ft; the calculated equilibrium unit weight will be approximately 105 lb/cu ft. The calculated equilibrium unit weight is calculated per ASTM C 567 Sec. 9.5, and represents the point at which the concrete in place reaches its air dry equilibrium density. Mixes with this density have proved to have good pumpability, performance and economy. Other design densities are attainable if needed; contact our sales office for details.

Slump: Slump at point of placement shall be 2 - 3 inches if placed conventionally and 3 - 5 inches if placed by concrete pump.

Comment: Design pump mixes so that the mix attains the desired strength with the higher slump needed for pumpability.

Air Entrainment: The air content shall be 6 percent, plus or minus 1.5 percent.

Comment: Typical pumped mixes will lose 2 inches of slump and 1% entrained air during pumping.

Field Control: Perform all quality control tests on lightweight concrete at the point of placement of the concrete. Adjust material proportions as needed to maintain proper slump, air content, fresh density and yield

Buildex Structural Lightweight Concrete
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