Aggregate Base Course
Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
Showing changes from Rev 3
to Rev 4
in Aggregate Base Course.
---
title: Aggregate Base Course
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- "Conformance certification from testing agency or geotechnical engineer"
- "Material certifications for each aggregate source delivered"
−default: [Field testing reports (density, moisture, gradation) indexed and signed, As-built record of finished top-of-base elevations, Conformance certification from testing agency or geotechnical engineer, Material certifications for each aggregate source delivered]
+default:
+ - "Field testing reports (density, moisture, gradation) indexed and signed"
+ - "As-built record of finished top-of-base elevations"
+ - "Conformance certification from testing agency or geotechnical engineer"
+ - "Material certifications for each aggregate source delivered"
```
…27 unchanged lines
### Testing for compaction acceptance shall not be performed by the Contractor or by an agency under the Contractor's direction.
−### The testing entity must be independent of the party whose work it accepts. {note}
+### The testing entity must be independent of the party whose work it accepts.
### The testing agency shall be experienced in aggregate base testing, equipped with calibrated nuclear density gauges or sand-cone equipment, and capable of providing results within the reporting times required by this specification.
…44 unchanged lines
### The testing technician shall correlate nuclear gauge readings to sand cone results at the start of base course production and whenever the apparent density-moisture relationship suggests gauge drift.
−# Materials {toc}
+# Aggregate — General Requirements {toc}
−## Aggregate — General Requirements {toc}
−
```datasheet
label: Aggregate Type
…7 unchanged lines
```
−### Aggregate base course material shall consist of clean, hard, durable, sound particles of crushed stone, crushed gravel, or crushed slag, free of organic matter, soft or weathered particles, clay lumps, vegetable matter, and other deleterious substances.
+## Aggregate base course material shall consist of clean, hard, durable, sound particles of crushed stone, crushed gravel, or crushed slag, free of organic matter, soft or weathered particles, clay lumps, vegetable matter, and other deleterious substances.
−### The aggregate shall be processed to conform to the gradation, plasticity, fines content, and durability requirements specified herein.
+## The aggregate shall be processed to conform to the gradation, plasticity, fines content, and durability requirements specified herein.
−### The intent of this specification is to deliver a well-graded, dense-graded aggregate that compacts to a high density with positive interparticle interlock between angular crushed faces, drains free of standing water, and provides uniform structural support across the full footprint of the overlying assembly. {note}
+## The intent of this specification is to deliver a well-graded, dense-graded aggregate that compacts to a high density with positive interparticle interlock between angular crushed faces, drains free of standing water, and provides uniform structural support across the full footprint of the overlying assembly. {note}
−### Recycled concrete aggregate (RCA) and reclaimed asphalt pavement (RAP) blends may be permitted as base course materials where allowed by the Engineer of Record, the geotechnical engineer, and the Authority Having Jurisdiction, and where the material is processed and tested to conform to the same gradation, plasticity, and durability requirements as virgin crushed stone.
+## Recycled concrete aggregate (RCA) and reclaimed asphalt pavement (RAP) blends may be permitted as base course materials where allowed by the Engineer of Record, the geotechnical engineer, and the Authority Having Jurisdiction, and where the material is processed and tested to conform to the same gradation, plasticity, and durability requirements as virgin crushed stone.
−### RCA tends to have higher absorption, lower density, and the potential for tufa formation in drainage paths, so its use shall be evaluated on a project-specific basis. {note}
+## RCA tends to have higher absorption, lower density, and the potential for tufa formation in drainage paths, so its use shall be evaluated on a project-specific basis. {note}
−### RAP-blended base shall be evaluated for binder content and its effect on compaction and stability.
+## RAP-blended base shall be evaluated for binder content and its effect on compaction and stability.
−## Gradation {toc}
+# Gradation {toc}
```datasheet
…25 unchanged lines
```
−### Aggregate base course shall be dense-graded, with a smooth and continuous distribution of particle sizes from the maximum size down through the fines.
+## Aggregate base course shall be dense-graded, with a smooth and continuous distribution of particle sizes from the maximum size down through the fines.
−### Open-graded materials with little or no fines are not aggregate base course and shall not be substituted for ABC under this specification.
+## Open-graded materials with little or no fines are not aggregate base course and shall not be substituted for ABC under this specification.
−### Dense gradation produces high density, high stiffness, and high stability — the coarse particles carry load by skeletal interlock and the fines fill the voids between coarse particles so the assembly behaves as a solid, while open-graded drainage layers serve a different purpose and require a separate specification. {note}
+## Dense gradation produces high density, high stiffness, and high stability — the coarse particles carry load by skeletal interlock and the fines fill the voids between coarse particles so the assembly behaves as a solid, while open-graded drainage layers serve a different purpose and require a separate specification. {note}
−### Maximum aggregate size shall be selected to suit the placed lift thickness and the surface tolerance requirements of the overlying assembly.
+## Maximum aggregate size shall be selected to suit the placed lift thickness and the surface tolerance requirements of the overlying assembly.
−### The largest particle shall not exceed two-thirds of the compacted lift thickness, and shall not exceed one-half of the total base thickness where the base is placed in a single lift.
+## The largest particle shall not exceed two-thirds of the compacted lift thickness, and shall not exceed one-half of the total base thickness where the base is placed in a single lift.
−### A smaller maximum size (3/4 in. or 1 in.) is preferred immediately beneath thin concrete topping slabs and architectural slabs where a coarse particle near the surface can telegraph through the slab as a hard spot or contribute to surface cracking, while a larger maximum size (1-1/2 in. or 2 in.) is appropriate for thick pavement sections where structural stiffness is the controlling criterion. {note}
+## A smaller maximum size (3/4 in. or 1 in.) is preferred immediately beneath thin concrete topping slabs and architectural slabs where a coarse particle near the surface can telegraph through the slab as a hard spot or contribute to surface cracking, while a larger maximum size (1-1/2 in. or 2 in.) is appropriate for thick pavement sections where structural stiffness is the controlling criterion. {note}
−## Fines Content {toc}
+# Fines Content {toc}
```datasheet
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```
−### The percentage of material passing the No. 200 sieve (75 μm) is the single most important secondary parameter of an aggregate base course, after gradation. {note}
+## The percentage of material passing the No. 200 sieve (75 μm) is the single most important secondary parameter of an aggregate base course, after gradation. {note}
−### Fines fill voids and contribute to compacted density, but excessive fines — particularly plastic fines — produce a base that holds water, becomes weak when saturated, pumps under traffic, and loses strength catastrophically when subjected to freeze-thaw cycling. {note}
+## Fines fill voids and contribute to compacted density, but excessive fines — particularly plastic fines — produce a base that holds water, becomes weak when saturated, pumps under traffic, and loses strength catastrophically when subjected to freeze-thaw cycling. {note}
−### The fines content shall be controlled at the source and verified at delivery.
+## The fines content shall be controlled at the source and verified at delivery.
−## Plasticity {toc}
+# Plasticity {toc}
```datasheet
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```
−### Plasticity indicates the presence and behavior of clay-sized fines: a non-plastic or low-plasticity material drains and dries, retains strength when wet, and resists frost heave, while a plastic-fines material holds water, swells, weakens, and pumps. {note}
+## Plasticity indicates the presence and behavior of clay-sized fines: a non-plastic or low-plasticity material drains and dries, retains strength when wet, and resists frost heave, while a plastic-fines material holds water, swells, weakens, and pumps. {note}
−### The plasticity index of the material passing the No. 40 sieve shall be determined per ASTM D4318 on every approved source.
+## The plasticity index of the material passing the No. 40 sieve shall be determined per ASTM D4318 on every approved source.
−### The plasticity index shall be retested whenever the visual or testing data suggest a source change.
+## The plasticity index shall be retested whenever the visual or testing data suggest a source change.
−## Sand Equivalent {toc}
+# Sand Equivalent {toc}
```datasheet
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```
−### The sand equivalent test (ASTM D2419) is a rapid field-applicable measure of the relative proportion of plastic fines and dust to acceptable sand-sized particles in the fine fraction of the aggregate, where a high value indicates clean, sand-dominated fines and a low value indicates clay-dominated fines. {note}
+## The sand equivalent test (ASTM D2419) is a rapid field-applicable measure of the relative proportion of plastic fines and dust to acceptable sand-sized particles in the fine fraction of the aggregate, where a high value indicates clean, sand-dominated fines and a low value indicates clay-dominated fines. {note}
−### The sand equivalent test is particularly useful as a production-control test because results are available in approximately one hour, unlike Atterberg limits which require multi-day specimen preparation. {note}
+## The sand equivalent test is particularly useful as a production-control test because results are available in approximately one hour, unlike Atterberg limits which require multi-day specimen preparation. {note}
−### The geotechnical engineer may direct sand equivalent testing in place of or in addition to plasticity index testing as a production-control measure.
+## The geotechnical engineer may direct sand equivalent testing in place of or in addition to plasticity index testing as a production-control measure.
−## Durability — Abrasion and Soundness {toc}
+# Durability — Abrasion and Soundness {toc}
```datasheet
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```
−### The aggregate shall be resistant to mechanical breakdown during handling, placement, and compaction, and to weathering breakdown over the service life of the assembly.
+## The aggregate shall be resistant to mechanical breakdown during handling, placement, and compaction, and to weathering breakdown over the service life of the assembly.
−### Mechanical durability shall be measured by the Los Angeles abrasion test (ASTM C131/C131M) and weathering durability shall be measured by sulfate soundness (ASTM C88/C88M).
+## Mechanical durability shall be measured by the Los Angeles abrasion test (ASTM C131/C131M) and weathering durability shall be measured by sulfate soundness (ASTM C88/C88M).
−### A high L.A. abrasion loss indicates an aggregate that will degrade under roller compaction, producing additional fines during placement and altering the in-place gradation from the as-tested gradation, which is a common cause of compaction tests that pass at the time of placement but lose density and develop pumping behavior shortly thereafter. {note}
+## A high L.A. abrasion loss indicates an aggregate that will degrade under roller compaction, producing additional fines during placement and altering the in-place gradation from the as-tested gradation, which is a common cause of compaction tests that pass at the time of placement but lose density and develop pumping behavior shortly thereafter. {note}
−### Sulfate soundness predicts the resistance of the aggregate to freeze-thaw breakdown over time and is critical in climates where the base course experiences saturated conditions during freezing weather. {note}
+## Sulfate soundness predicts the resistance of the aggregate to freeze-thaw breakdown over time and is critical in climates where the base course experiences saturated conditions during freezing weather. {note}
−## Fractured Particles {toc}
+# Fractured Particles {toc}
```datasheet
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```
−### For crushed gravel sources, the percentage of fractured particles per ASTM D5821 is the principal means of ensuring that the rounded river-run particles have been broken to expose angular faces that interlock under compaction. {note}
+## For crushed gravel sources, the percentage of fractured particles per ASTM D5821 is the principal means of ensuring that the rounded river-run particles have been broken to expose angular faces that interlock under compaction. {note}
−### Crushed-stone sources are inherently 100 percent fractured by the crushing process and do not require fractured-particle verification, but the source-qualification submittal shall describe the crushing process so the verification can be waived appropriately.
+## Crushed-stone sources are inherently 100 percent fractured by the crushing process and do not require fractured-particle verification, but the source-qualification submittal shall describe the crushing process so the verification can be waived appropriately.
−## California Bearing Ratio {toc}
+# California Bearing Ratio {toc}
```datasheet
…9 unchanged lines
```
−### CBR is a strength-based acceptance criterion used by pavement designers and by military and FAA specifications. {note}
+## CBR is a strength-based acceptance criterion used by pavement designers and by military and FAA specifications. {note}
−### Where the pavement section design is based on a specific assumed CBR of the base course, that CBR shall be verified by laboratory testing of the source material at the specified compaction.
+## Where the pavement section design is based on a specific assumed CBR of the base course, that CBR shall be verified by laboratory testing of the source material at the specified compaction.
−### CBR testing alone shall not be used as an acceptance basis and shall always be paired with gradation, plasticity, and density requirements, because a material can exhibit acceptable CBR while failing other parameters that govern long-term performance.
+## CBR testing alone shall not be used as an acceptance basis and shall always be paired with gradation, plasticity, and density requirements, because a material can exhibit acceptable CBR while failing other parameters that govern long-term performance.
−## Separation Geotextile {toc}
+# Separation Geotextile {toc}
```datasheet
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```
−### Where the subgrade is fine-grained (silt, clay, or silty/clayey sand) and saturated or near-saturated conditions are anticipated, a separation geotextile shall be installed between the subgrade and the aggregate base course to prevent migration of subgrade fines upward into the base voids under cyclic loading.
+## Where the subgrade is fine-grained (silt, clay, or silty/clayey sand) and saturated or near-saturated conditions are anticipated, a separation geotextile shall be installed between the subgrade and the aggregate base course to prevent migration of subgrade fines upward into the base voids under cyclic loading.
−### Without separation, subgrade fines pump into the base voids over time, reducing base permeability, contaminating the base gradation, and eventually destabilizing the assembly. {note}
+## Without separation, subgrade fines pump into the base voids over time, reducing base permeability, contaminating the base gradation, and eventually destabilizing the assembly. {note}
−### The need for a separation geotextile shall be determined by the geotechnical engineer based on the subgrade soil type, anticipated moisture conditions, and the importance of the overlying assembly.
+## The need for a separation geotextile shall be determined by the geotechnical engineer based on the subgrade soil type, anticipated moisture conditions, and the importance of the overlying assembly.
# Subgrade Preparation and Acceptance {toc}
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min: 92
max: 100
− setpoints: [95, 98]
+ setpoints: [92, 95, 98, 100]
default: 95
```
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## Defects in the base course that produce surface course failures discovered after the warranty period may constitute latent defects extending the Contractor's responsibility beyond the warranty term where the defect can be tied to non-conforming materials, inadequate compaction, or undocumented failing tests.