Technical Questions

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Definition of controlled low-strength material (CLSM)

Q. Where should a controlled low-strength material be used?


A. A controlled low-strength material (CLSM) is a self-consolidating, cementing material used primarily as a backfill as an alternative to compacted fill (ACI 229R). Several terms have been used to describe this material, including flowable fill, unshrinkable fill, controlled density fill, flowable mortar, plastic soil-cement, and soil-cement slurry; however, the correct terminology is controlled low-strength material. CLSM is intended to result in a compressive strength of 1200 psi (8.3 MPa) or less.


References: SP-1(02); ACI 229R-13; ACI 230.1R-09; SP-150; ACI CT-23

Topics in Concrete: CLSM; Concrete Fundamentals; Materials; Soil Cement

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