LIGHTWEIGHT AGGREGATE BORROW
PART 1 GENERAL
1.1SECTION INCLUDES
A.Lightweight aggregate borrow for use in compacted roadway
embankments or as backfill.
1.2RELATED SECTIONS
A.Section 02056: Embankment, Borrow, and Backfill
B.Section 02075: Geotextiles
1.3REFERENCES
A.AASHTO T 11: Materials Finer than 75 μm (No. 200) Sieve in Mineral
Aggregates by Washing
B.AASHTO T 27: Sieve Analysis of Fine and Coarse Aggregates
C.AASHTO T 99: Moisture-Density Relations of Solid using a 2.5-kg (5.5-lb)
Rammer and a 305-mm (12-in.) Drop
D.UDOT Materials Manual of Instruction
E.UDOT Minimum Sampling and Testing Requirements
1.4DEFINITIONS Not Used
1.5SUBMITTALS
A.Provide the following for review before delivering material to the project:
1.Supplier and source of material.
2.Gradation analysis. Refer to AASHTO T 27 and AASHTO T 11.
3.Maximum Dry Density and Optimum Moisture Determination. Refer
to AASHTO T 99.
Lightweight Aggregate Borrow
B.Method to compact lightweight aggregate borrow for information. Include
at least the following:
1.Equipment and method for compaction
2.Pictures of the test fill before and after compaction to demonstrate
the condition of the aggregates before and after compaction
3.In-place moist density test results taken from test fill
4.A revised method to compact lightweight aggregate including a
method to prevent damage to lightweight aggregates if in-place aggregates have broken down.
1.6ACCEPTANCE
A.Acceptance sampling and testing is according to UDOT Minimum
Sampling and Testing Requirements.
1.Follow the same requirements as listed for the lightweight
aggregate material as for Embankment for Bridge in 02056 Embankment, Borrow and Backfill.
a.Perform at least eight in-place density tests for each defined
lot.
B.Meet the following target compacted in-place moist densities, or as shown:
1.Scoria Aggregate: 65 to 78 pcf
2.Expanded Shale Aggregate: 55 to 75 pcf
3.Pumice Aggregate: 42 to 60 pcf
4.Steel Slag Aggregate: 85 to 100 pcf
C.The average compacted moist density per lot must be between the limits
specified for the applicable materials in Article 1.6 B.
1.No single fill density test may have a compacted moist density that
is 2 pcf, or more, greater than that specified maximum density for the lightweight aggregate borrow supplied.
2.High densities of compacted aggregate may indicate that the
aggregate has broken down during placement and compaction.
3.The work may remain in place if the Engineer decides that the work
is adequate to serve the design purpose.
PART 2 PRODUCTS
2.1GENERAL
A.Provide lightweight aggregate borrow consisting of one of the aggregate
types shown in this Section, Articles 2.2 through 2.5.
Lightweight Aggregate Borrow
B.Deliver lightweight aggregate borrow materials which are:
1.Chemically inert and durable
a.Materials which are not durable tend to crush or fracture
during the compaction process. This may lead to increased densities.
2.Free of contamination from chemical or petroleum products test
2.2SCORIA
A.Meet the gradation in Table 1:
Table 1 Scoria Aggregate Gradation Requirements Sieve Size Percent Passing 3 inch 100 1 inch 80 – 100 3/8 inch 40 – 100 No. 4 10 – 70 No. 50 0 – 25 No. 200 0 – 15
2.3EXPANDED SHALE
A.Meet the gradation in Table 2:
Table 2 Expanded Shale Gradation Requirements Sieve Size Percent Passing 1 inch 100 1/2 inch 90 – 100 3/8 inch 40 – 100 No. 4 0 – 40 No. 16 0 – 10 No. 100 0–5
Lightweight Aggregate Borrow
2.4PUMICE
A.Meet the gradation in Table 3:
Table 3 Pumice Gradation Requirements Sieve Size Percent Passing 2 inch 100 1 inch 80 – 100 1/2 inch 5 – 50 No. 4 0 – 25 No. 50 0 – 18 No. 200 0 – 10
2.5STEEL SLAG
A.Meet the gradation in Table 4:
Table 4 Steel Slag Gradation Requirements Sieve Size Percent Passing 3 inch 100 1 ½ inch 80 – 100 3/4 inch 20 – 100 3/8 inch 0 – 20 No. 4 0 – 10 No. 200 0–5
2.6EQUIPMENT
A.Compact lightweight aggregate borrow using either a smooth-drum
vibratory roller, or track-mounted earthwork equipment.
1.Use equipment having an operating weight no greater than 12 tons.
PART 3 EXECUTION
3.1PREPARATION
A.Prepare subgrade according to Section 02056, or as shown before placing
lightweight aggregate borrow.
Lightweight Aggregate Borrow
3.2TEST FILL
A.Conduct a test fill to demonstrate the adequacy of the selected
compaction method.
1.Notify the Engineer of the location and time of placement of the test
fill.
a.The test fill may be incorporated into the finished work if it
conforms with the requirements of the contract.
2.Include results of test fill in submitted method to compact
lightweight aggregate borrow. The test results to include at least the following:
a.Compacted in-place density vs. compactive effort applied
according to Article 3.2 B 1.
b.Evaluation of the breakdown of aggregates for each
compactive effort condition.
B.Place lightweight aggregate borrow in a test fill as specified in this Section,
Article 3.3 and compact to 95 percent of the maximum laboratory density as determined by AASHTO T 99.
1.Compact test lifts with various numbers of passes with a small
vibratory drum roller (such as a Cat CS-433C), at low amplitude; or a medium vibratory drum roller (such as a Cat CS-563C), at low amplitude.
3.3CONSTRUCTION PROCEDURES
A.Place the lightweight aggregate borrow in uniformly thick lifts with a
maximum loose thickness of 12 inch.
B.Place lightweight scoria or steel slag aggregate borrow at moisture
content high enough to obtain the required compaction, while remaining below the maximum target compacted moist in-place density specified for the material.
C.Do not add moisture to lightweight pumice or expanded shale aggregate.
1.Cover stockpiles and the surface of placed material of pumice or
expanded shale aggregate after the last work-shift at the end of each work-week.
2.Cover stockpiles of pumice or expanded shale aggregate during
anticipated periods of precipitation during the work-week.
D.Take necessary measures to avoid crushing the aggregate.
1.Adjustments to the compaction equipment lift thickness, and the
number of passes may be required, if crushing occurs.
Lightweight Aggregate Borrow
3.4PROTECTION
A.Do not extend lightweight aggregate borrow into the designated untreated
base course zone.
B.Cover the final surface of lightweight aggregate borrow using Separation
Geotextile according to Section 02075.
END OF SECTION
Lightweight Aggregate Borrow
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Source: Utah Standard Specifications for Road and Bridge Construction, 2026 Edition. Pages 287–292 of 1,331.
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