Development of a Recommended Practice for Use of Controlled Low-Strength Material in Highway Construction (2008) / Chapter Skim
Currently Skimming:
Appendix D - Recommended Practice for CLSM
Appendix D - Recommended Practice for CLSM
Pages 129-139
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 129... ...
Backfill as intended in this Recommended Practice relates to the infill material to cover pipes (in trench applications) up to a specified grade (usually equal to the grade of undisturbed earth on either side of a trench wall)
|
From page 130... ...
Backfill also is not the same as void fill; the primary difference is that backfill is placed against a structure with the purpose of providing at least some structural resistance to loads.
|
From page 131... ...
For CLSM mixtures with similar compressive strengths, CLSM without aggregate is easier to excavate than CLSM containing fine aggregate, which is easier to excavate than CLSM containing coarse aggregate (with or without fine aggregate)
|
From page 132... ...
4.1.3.2. A sample work description could state: "Furnish and install backfill to provide necessary structural support for utilities, trench walls, retaining walls, abutments, and other applications." Material specifications should note that CLSM may be composed of some or all of the following components and their associated specification or test method: Aggregate AASHTO M 6 or as approved by the engineer.
|
From page 133... ...
m from the discharge location. For backfill applications, provide suitable vertical wall containment to ensure that the CLSM will not flow into areas beyond those specified on the plans.
|
From page 134... ...
Material acceptance shall be based on all criteria specified, plus local experience with excavatability, including the following: 4.1.3.6.4.1.1. Strength: a 28-day compressive strength of no more than [1 MPa]
|
From page 135... ...
Utility bedding also is not the same as void fill; the primary difference is that utility bedding is placed underneath the utility structure with the purpose of providing supporting strength to the utilities and distributing loads and reactions.
|
From page 136... ...
Void fill relates to the infill material to occupy empty spaces created by erosion, construction, abandonment, and other activities.
|
From page 137... ...
4.4.1.3. Bridge approach fill is not the same as utility bedding, backfill, or void fill; the primary difference is that bridge approach fill is placed against a structure with the purpose of providing adequate structural resistance to loads.
|
From page 138... ...
Water permeability is an important issue for bridge approach fill. A very impermeable CLSM mixture may lead, depending on the application design, to excess water being unable to flow through or around the CLSM, which may lead to a buildup of water pressures against the abutment or to washouts at the CLSM-soil interface.
|
From page 139... ...
For example, on a trench fill application in a roadway, if noticeable subsidence of the CLSM occurs that results in roadway damage, note should be taken. If excavation of a utility trench backfill requires more powerful equipment than was anticipated based on the original project material and construction specification (e.g., if the removability was designed for hand tools and requires power equipment)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.