Specification For:
Controlled Low-Strength Materials (CLSM)
Scope:
This Work consists of furnishing and placing
controlled low strength materials (CLSM) in accordance with the Contract
Documents, Jackson County permit requirements, or as directed by the Engineer.
All products shall be pre-approved by the County Engineer in accordance to this
specification.
Definitions:
CLSM - A highly flowable lean concrete mix consisting of a
mixture of cement, fly ash, densely graded mineral aggregates, water, and
admixtures. CLSM shall be capable of freely flowing to fill all voids in
trenches or other areas without compaction or other additional effort, shall be
of uniform density, shall be of low permeability to prevent migration of
adjacent fines into the set mix, and shall excavate easily at any later time
with minimal risk of damage to buried services.
Fine Aggregate CLSM - A CLSM
containing a maximum size aggregate of 3/8-inch.
Materials:
All material specifications shall conform to the latest version of the Oregon Standard Specifications for Construction that Jackson County Roads has issued Supplemental Standard Specifications for. Furnish Materials meeting the following requirements from the Oregon Standard Specifications for Construction and/or modified in the Jackson County Supplemental Standards or Special Provisions:
- Admixtures 02040
- Fly Ash 02030.10
- Portland Cement 02010.10
- Water 02020
Aggregates shall be a densely graded virgin rock or appropriate recycled material which produces a mix meeting all requirements within this Specification. A minimum of 50 percent of the total aggregate weight shall pass a #8 sieve and no more that 5 percent of the total aggregate by weight may pass a #200 sieve. The maximum size aggregate for fine aggregate CLSM shall pass a 3/8-inch sieve.
Performance Specification:
CLSM shall meet the following requirements:
• Flowability - The mix shall have a slump of between 6 and 8 inches as per
AASHTO Designation T 119-82 or ASTM Designation C 143
• Compressive strength - The mix shall have a 28-day compressive strength of
between 50 and 150 psi, per AASHTO Designation T 22-90 or ASTM Designation C 39
Mix Design and Testing:
Vendors who purpose to supply CLSM for work within Jackson
County right-of-way shall submit a mix design and test results to Jackson
County Roads for approval. Jackson County will maintain an approved products
list on the Jackson County Roads website. The mix submittal shall include the
following information:
• Company Name and Address
• Company Contact Information
• Identifying name and/or number for the mix design
• Mix Design (including aggregate type and gradation)
• Certified test results for flowability, and compressive strength
Submittals which do not contain
all required information shall not be considered.
Products that are rejected in the
field may be removed from the approved list at the discretion of the County
Engineer.
Mixing and Placement:
CLSM shall be mixed accordance with subsection Sections 00756.20
or 00756.21; delivered in a truck mixer conforming to 00756.22; and conveyed in
accordance with 00540.22.
Contractor shall provide
and maintain steel jump plates with locks as required for traffic and safety.
In paved areas open to the public, the top of the trench shall be patched with
Asphalt Concrete Pavement not sooner than the CLSM is adequately set (generally
48 hours), nor longer than 10 calendar days following placement of the CLSM.
When CLSM is delivered to
the job site, delivery tags shall be collected from the delivery driver and
provided to the Jackson County Inspector or Engineer. The delivery tag shall
contain the supplier name and the mix identifying name and/or number as
identified in the supplier’s submitted mix design.
The Jackson County
Inspector or Engineer may reject any mix that does not appear to meet the
requirements of this Specification (for example: segregation, insufficient
slump, or open graded aggregates). The Jackson County Inspector or Engineer may
require removal of any mix that has been placed but doesn’t perform as
specified.
Only fine aggregate CLSM
will be allowed in pipe zones or trenches of less than 1-foot width.
In the event of extremely cold or wet conditions, and with the
approval of the Jackson County Inspector or Engineer prior to use, an approved
fine aggregate CLSM may have up to 94 additional pounds of cement per cubic
yard added to the design mix to facilitate setting.