Low Density Controlled Low Strength Material, is cellular concrete’s special classification within the American Concrete Institute’s CLSM standard, PRC-229-R-13(22). CLSM, or Controlled Low Strength Material, generally refers to flowable fill or mix designs specifically formulated for relatively low, but predictable, strengths. The preformed foam used to generate cellular concrete facilitates the Low Density characteristics of Low Density Controlled Low Strength Material. Instead of sand and stone aggregate, the Low Density Controlled Low Strength Material has uniformly-distributed air bubbles. This lowers unit weight significantly.
Types of LD-CLSM
Low Density Controlled Low Strength Material can be either pervious or non-pervious. CJFill-Ultra Lightweight, CJFill-Standard, and CJFill-Under Water are all types of non-pervious LD-CLSM. We generate non-pervious using Aerlite-iX preformed cellular concrete foam. We use Aquaerix preformed cellular concrete foam to generate pervious material.
Uses for LD-CLSM
The primary driver of Low Density Controlled Strength Material use instead of standard CLSM is load reduction. Applications range from abandoning pipes to void filling below bridge abutments, reducing loads on underground utilities and reducing settlement without the use of deep foundations.
Typical Mix Designs
Cellular concrete typically ranges from 20lb/cuft wet cast density up to around 70lb/cuft. These densities provide strengths from around 50psi to greater than 1,000psi. Density is effectively infinitely variable within that range, with a relatively linear relationship between density and compressive strength.
Relatively common mixes are 25PCF, 30PCF (both CJFill-Ultra Lightweight) and 70PCF (CJFill-Under Water). 20PCF wet cast density is the go-to mix design for maximum load reduction. Pervious LD-CLSM (CJFill-High Permeability) will sink, even if it’s lighter than water. 30PCF is a relatively common mix for pipe abandonments, annular space grouting and other utility-related work. Like granular backfill, use non-woven geotextile to separate pervious material from adjacent soils.
Material as light as 25lb/cuft will displace water in abandonment & annular space grouting applications. To displace water in open placements, CJGeo uses 65 to 75lb/cuft material.
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