CO FLAP SH5(1) Mount Blue Sky Hwy Pavements Report Signed.pdf

MOUNT BLUE SKY HIGHWAY

CLEAR CREEK COUNTY, COLORADO

CO FLAP SH5(1)

PAVEMENT AND MATERIALS REPORT

MARCH 2024

Report prepared by:

U.S. Department of Transportation Federal Highway Administration (FHWA) Central Federal Lands Highway Division

Lakewood, Colorado http://www.google.com/imgres?sa=X&biw=1280&bih=819&tbm=isch&tbnid=gtpyJEKxSQX6SM:&imgrefurl=http://portal.hud.gov/hudportal/HUD?src=/press/press_releases_media_advisories/2010/HUDNo.10-242&docid=0hzyuk4oobnONM&imgurl=http://portal.hud.gov/hudportal/images/hudimg?id=dot_logo_41193.jpg&w=520&h=528&ei=uGw7Uoy6Ksjk4AOC_IDQBw&zoom=1&iact=hc&vpx=567&vpy=131&dur=635&hovh=226&hovw=223&tx=151&ty=150&page=1&tbnh=154&tbnw=162&start=0&ndsp=30&ved=1t:429,r:26,s:0,i:171

CO FLAP SH5(1) Mount Blue Sky Highway ii

Written by: ________________________________________________________ Robert Norick, Staff Pavements & Materials Engineer

Reviewed by: ________________________________________________________ Mike Voth, Pavements & Materials Team Lead

Approved for distribution by:

Mike Voth, Pavements & Materials Team Lead

Electronic Distribution:

Construction Project Development Project Management Technical Services iii

TABLE OF CONTENTS

I. INTRODUCTION

II. EXPLORATION

III. CLIMATE

IV. SOILS & GEOLOGY

V. EXISTING PAVEMENT CONDITIONS

VI. PAVEMENT DESIGN INPUTS

VII. PAVEMENT RECOMMENDATIONS & DISCUSSION

VIII. MATERIALS RECOMMENDATIONS

APPENDICES

A – Vicinity & Boring Maps B – Boring Log & Lab Reports C – Site Investigation Photos D – CDOT SH 5 Summit Lake Geotechnical Report (2009) E – Asphalt Binder & Climate Data F – Design Calculations & Figures G – Project Specific SCRs

I. INTRODUCTION

This report is written to document the existing road conditions and provide pavement recommendations for the planned CO FLAP SH5(1) project in central Colorado. The project consists of the reconstruction of 0.70 miles (Milepost 8.8 to 9.5) of the paved Mount Blue Sky Highway (State Highway 5) at Summit Lake (Elevation 12,836 feet) to mitigate subsidence and heaving related to the freeze-thaw cycles of the high elevation permafrost. Milepost 8.8 is located immediately east of the upper/east overflow parking area. Summit Lake’s lower/west main parking area is located at Milepost 9.15. The existing 22-foot pavement width with a drive lane in each direction, as well as, the existing 20 mph posted speed limit will be maintained with the proposed reconstruction.

Mount Blue Sky (formerly Mount Evans) is a prominent 14,271-foot peak west of the City of Denver in Clear Creek County, Colorado; approximately 13 miles southwest of Interstate 70’s Exit 240 at Idaho Springs. The road begins at its intersection with State Highway 103 and proceeds southwesterly 14 miles to the peak’s summit. The scenic byway was constructed between 1923 and 1930 by the Federal Bureau of Public Roads in cooperation with the United States Forest Service, Denver Mountain Parks, and the Colorado State Highway Commission. Besides the 160-acre Summit Lake Park (City and County of Denver property) between Mileposts 9.0 and 9.5, Mount Blue Sky lies within the Arapaho National Forest. The Colorado Department of Transportation (CDOT) maintains the road under easement and license agreements with both the Forest Service and Denver Mountain Parks. The Mount Blue Sky Highway is the highest paved road in North America and is popular with both motorists and cyclists. CDOT plows the road in late May and the road is typically open from Memorial Day weekend through Labor Day for approximately four months depending on weather.

Each year there are multiple bicycle and motorcycle accidents through the project site with some resulting in serious injuries. Cars frequently bottom out at heave locations and cyclists complain regarding the extremely distressed pavement. When the summit must be evacuated several times a week due to advancing summer thunderstorms, the pavement subsidence and heaves slow the evacuation efforts.

II. EXPLORATION

On September 17-18, 2020, a pavement and geotechnical investigation was conducted for the project consisting of 7 geotechnical borings (20 to 30 feet deep) using a down-the-hole air hammer drilling system (ODEX). Standard penetration tests (SPT) with both SPT and brass California liner samples were conducted at 5-foot intervals for each boring with an additional SPT at a shallow 2.5-foot depth. The locations of the soil borings are shown on the boring map in Appendix A. CFLHD (Central Federal Lands Highway Division) personnel logged the findings including depth of boring and subgrade soils, SPT data, visual soil classification, pavement and aggregate base thicknesses, and areas of distress.

SPT and brass liner samples, as well as, three bulk subgrade samples were submitted to the CFLHD lab for testing to determine the soil classifications, in addition to, other engineering properties (R-Value, pH, and resistivity). The boring log and lab reports are provided in Appendix B, while Appendix C provides photos from the field investigation.

III. CLIMATE

Climate data was obtained from the Western Regional Climate Center for the Berthoud Pass, Colorado weather station. Climate data was not available for Summit Lake on Mount Blue Sky. The Berthoud Pass weather station is the closest weather station with a similar climate. The data is summarized in Table 1 below and provided in Appendix E.

The project is located within the Rocky Mountains of central Colorado with an average precipitation of approximately 37.48 inches. The project is located above timberline at an elevation of approximately 13,000 feet. The weather at this elevation is extremely harsh, creating a difficult environment for a paved road. The area receives moisture from both rain and snow depending upon the time of year. The area receives the majority of its moisture from snow (approximately 400 inches annually) with a lesser amount from summer thunderstorms.

Table 1. Weather Data

Month Average

HIGH

Record

HIGH

Average

LOW

Record

LOW

Average

PRECIP.

January 21.2 42 1.4 -33 3.49 February 24.2 47 2.0 -34 2.90

March 28.7 50 6.2 -24 4.11 April 36.2 57 13.6 -12 4.43 May 45.0 62 23.1 -3 3.85 June 54.2 70 32.0 11 2.23 July 61.9 76 39.2 26 2.45

August 59.9 75 38.0 21 2.63 September 53.0 73 31.0 4 2.05

October 42.4 63 20.9 -5 2.36 November 30.4 54 9.8 -28 3.36 December 23.2 47 3.2 -30 3.63

Temperatures are in °F and precipitations are in inches.

IV. SOILS & GEOLOGY

Based upon the pavement and geotechnical investigation, the underlying subgrade soils through the project limits generally consist of frost susceptible silty sands (ASTM SM / AASHTO A-1-b soils). The Summit Lake project site is located in a glacial cirque; a bowl shaped valley with over-steepened headwalls and a sill where the glacier flowed downhill out of the valley. The Summit Lake cirque is located above timberline with low-lying tundra plants and grasses growing around surface boulders. Permanently frozen ground (permafrost) is present throughout the valley. A portion of the ground above the permafrost thaws during the summer and refreezes during the winter (referred to as the active zone). The depth of the active zone varies naturally depending upon altitude, climate, slope aspect, and vegetation cover. Paved roads absorb heat from the sun and tend to increase the depth of the active zone. Previous investigations by CDOT and Colorado State University indicate that the depth of the active zone varies between 6 feet for vegetated areas to more than 15 feet under the road’s pavement. Thawing of ice-rich permafrost produces settlement of the unconsolidated sediments. In combination with traffic loading and vibrations, longitudinal subsidence beneath the road centerline can create an inverted crown. Additionally, portions of the road were constructed over wetland and fen areas with high organic content. This was observed in the shallow samples (top 5 feet) from Boring BH 20-10 which contained organic/peat material (PT).

Organic soils tend to be highly porous and compressible further contributing to the subsidence along the road. Localized deformations also occur from boulders being heaved and thrust upward. Summit Lake does not freeze solid during the winter which may create a non-frozen groundwater layer between the bottom of the active zone and the top of permafrost for areas adjacent to the lake. Summit Lake is at the headwaters of Bear Creek and outlets through a CMP culvert near Boring BH 20-06 at Milepost 9.25.

V. EXISTING PAVEMENT CONDITIONS

The existing asphalt pavement through the project site (Milepost 8.8 to 9.5) is in poor condition with extensive transverse, longitudinal, and block cracking, in addition to, areas with subsidence, heaving, fatigue cracking, and potholes. The pavement investigation found an existing pavement section consisting of 4 to 10 inches of asphalt over 3 to 6 inches of aggregate base. The road was last resurfaced in 1994 and CDOT periodically corrects bumps and dips with localized asphalt overlays. Between Mileposts

8.90 and 9.10, extensive subsidence has occurred resulting in an inverted crown. This section of road was originally constructed with cut north of the road and fill south of the road. This section of road has subsided into more of a through-cut. The pavement investigation also noted subsidence at Milepost 8.85 towards the middle of the east/upper parking lot (4.5-foot asphalt thickness per CDOT borings) and between Mileposts 9.36 and 9.43. Additionally, a large notable boulder heave is located at Milepost 8.95 and a CMP culvert has been thrust through the asphalt pavement near Milepost 9.0.

VI. PAVEMENT DESIGN INPUTS

The pavement design for the Mount Blue Sky Highway utilized design criteria established in the Federal Lands Highway Project Development Design Manual (PDDM) and the 1993 AASHTO Guide for Design of Pavement Structures (AGDPS). The criteria shown in Table 2 below were selected based on the project’s scope and traffic levels.

Table 2. Design Criteria Design Performance Period (4R) 25 years Initial Serviceability 4.2 Terminal Serviceability 2.0 Design Reliability Level 75% Overall Standard Deviation 0.49 Annual Traffic Volume Growth Rate 2.0% Directional Distribution (dead end road) 50%

Traffic

The majority of the road’s vehicle traffic is primarily for recreational purposes (sightseeing on a 14,000 foot peak, hiking, wildlife and wildflower viewing, cycling, etc.)

with a minor amount of traffic generated by scientific research. CDOT plows the road in late May and the road is typically open from Memorial Day weekend through Labor Day depending upon weather conditions. Vehicles over 30 feet long (e.g. RVs) are not recommended on the steep, narrow, winding road. The Forest Service operates a fee station just south of the road’s intersection with State Highway 103. The fee station sells day passes for vehicle access to the scenic byway. Based upon the fee station data, over 75,000 vehicles transverse this roadway each year during its short 4 month season;

equivalent to a two-way annual average daily traffic (AADT) of approximately 400.

Truck traffic is estimated to be just 2% of the road’s AADT; 1% Class 5 two-axle motor homes, garbage trucks, and septic trucks and 1% Class 6 three-axle plows. The vast majority of the vehicles that use this route are passenger vehicles, pickups, and SUVs (estimated at 98% of the AADT). Accurate traffic load estimates expressed as 18-kip equivalent single axle loads (ESALs) are critical for the pavement design. Load estimates are based on vehicle counts and classifications with a 25-year, 2% growth factor of 32.

Standard load equivalency truck factors are used to convert the various vehicle axle loads to 18-kip ESALs. The following truck factors were assumed for the aforementioned vehicle classifications in accordance with PDDM Exhibit 11.2-A: 0.002 for Class 2-3, 0.5 for Class 5, and 1.0 for Class 6. Based upon the design criteria and assumptions shown above and the 1993 AASHTO design procedure, the project’s 25-year-18-kip ESALs are estimated to be 39,656 as provided in Appendix F. According to PDDM Section 11.2.1.2, a minimum of 50,000 ESALs shall be used for the design of paved roads.

Subgrade Soil Resilient Modulus

Three subgrade samples were submitted to the CFLHD laboratory for soil classification.

The existing pavement subgrade consists of AASHTO A-1-b silty sands. R-Values (resistance values on a scale of 0 to 100 per AASHTO T 190) were determined for two of the subgrade samples with an average R-Value of 73. As a comparison, PDDM Table 11.2-C indicates that Section 302 Minor Crushed Aggregate Base has an R-Value greater than 65, while Section 301 Crushed Aggregate Base has an R-Value greater than 80.

PDDM Exhibit 11.4.2.C indicates that an R-Value of 73 correlates to a Resilient Modulus greater than 20,000 psi. The Resilient Modulus derived from this exhibit is representative of a well-drained subgrade under optimum conditions. When a soil is saturated, the Resilient Modulus is dramatically reduced (10% to 40% of the R-Value Resilient Modulus). Table 4.2 from the 1993 AASHTO design procedure (AGDPS) provides typical Resilient Modulus values under dry, wet, saturated, and frozen conditions (See Appendix F). The Mount Blue Sky Highway typically opens by Memorial Day weekend for a four-month season. The subgrade soils transition from saturated thawing soil in the spring to a dry soil by late summer. Table 4.2 indicates that soils with an “optimum” Resilient Modulus of 20,000 psi are indicative of “very good” soils with an average Resilient Modulus of 10,000 psi for the spring through fall timeframe. A Resilient Modulus of 10,000 psi was used for the project’s pavement design.

Structural Layer Coefficients

Standard structural layer coefficients were selected for asphalt concrete pavement (0.40) and aggregate base (0.12) in accordance with Exhibit 11.2-C of the PDDM. A drainage coefficient of 1.0 was utilized for all proposed layers.

Structural Number Calculations

The 1993 AASHTO pavement design procedure is used to determine the required pavement structural number (SN) for the project. Based upon the ESALs, the subgrade Resilient Modulus, and the aforementioned design criteria, the following required 25-year pavement design structural number is calculated (See Appendix F).

Required SN for Mount Blue Sky Highway = 1.69 inches

VII. PAVEMENT RECOMMENDATIONS & DISCUSSION

Project Recommendations

CFLHD’s Geotechnical Group is proposing to raise the road with a rock filled Air Convection Embankment (ACE) between the start of the project (Milepost 8.8) and the lower/west main parking area (Milepost 9.1); area with extensive subsidence with inverted crown (see Final Geotechnical Report). The ACE is intended to extract and reduce the heat created by the pavement, as well as, conveying storm runoff across the embankment. The proposed rock filled embankment to be 4-foot high with a nonwoven separation-stabilization geotextile on both the top and bottom to prevent the voids from being filled with sand and fines. The rock fill to range in size between 4 and 12 inches.

The top of the rock fill embankment to be leveled with choker rock to accommodate construction vehicle traffic and geotextile placement.

It is recommended to salvage the existing asphalt and base to a 10” depth and remove and stockpile the material for use in constructing the recommended pavement sections. There will likely be an insufficient quantity of recycled aggregate, and therefore, some crushed aggregate will still need to be imported. In accordance with the 1993 AASHTO design procedure, a 25-year pavement design requires a Structural Number (SN) of 1.69. After evaluating alternatives, the following two pavement structural sections are recommended.

Pavement Section A (for areas with proposed ACE rock fill)

3 inches of Asphalt Concrete Pavement (SN = 3” x 0.40 = 1.20”) 6 inches of Recycled or Crushed Aggregate Base (SN = 6” x 0.12 = 0.72”) Class 1, Type C Separation-Stabilization Geotextile

TOTAL SN = 1.92 inches

Pavement Section B (for areas without ACE rock fill)

3 inches of Asphalt Concrete Pavement (SN = 3” x 0.40 = 1.20”) 12 inches of Recycled or Crushed Aggregate Base (SN = 12” x 0.12 = 1.44”) Class 1, Type C Separation-Stabilization Geotextile

TOTAL SN = 2.64 inches

For Pavement Section B, the thickness of the base and pavement structural number were increased for improved constructability for the low lying areas adjacent to Summit Lake.

VIII. MATERIALS RECOMMENDATIONS, SCRs, AND

CONSTRUCTION CONSIDERATIONS

Selection of Asphalt Binder

LTPPBind online, the PDDM standards, and the CDOT binder selection criteria were utilized for the selection of the asphalt binder for the project (See Appendix E).

LTPPBind online recommends a PG 52-34 binder which is not available in Colorado.

Based on these considerations, a PG 58-34 binder is recommended for the project. This binder grade is readily available and commonly used by the Colorado DOT.

Materials for Culvert Pipe / Cement

The subgrade’s pH and resistivity do not show a need to specify special culvert materials in accordance with the pipe selection criteria in Appendix F. The subgrade soils are considered non-corrosive.

SCRs and Construction Concerns

CFLHD’s standard SCRs for pavements and materials are expected to be used apart from SCRs for the following FP-14 sections as provided in Appendix G: Section 308 Recycled Aggregate and Section 403 Asphalt Concrete. The 308 SCR to address the use of recycled aggregate as crushed aggregate base for the recommended pavement sections.

This recycled aggregate is to be generated from the existing asphalt and base for the length of the project. The removal, processing, and stockpiling cost will not be paid for separately but will be included in the cubic yard price for the Section 308 recycled aggregate base. The 403 SCR to require a material transfer vehicle (MTV) for the asphalt paving and to tailor Subsection 403.02 for CDOT asphalt mixes.

Bid Items

The FP-14 pay items for the proposed structural sections are provided in Table 3 below.

Table 3: Recommended Pay Items Item

Number Item Description Unit

20420-0000 Embankment Construction (rock) CUYD 30202-2000 Roadway Aggregate, Method 2 TON 30802-0000 Recycled Aggregate Base CUYD 40301-0100 Asphalt Concrete Pavement, Type 1 TON

APPENDICES

A – Vicinity & Boring Maps

B – Boring Log & Lab Reports

C – Site Investigation Photos

D – CDOT SH 5 Geotechnical Report (2009)

E – Asphalt Binder & Climate Data

F – Design Calculations & Figures

G – Project Specific SCRs

APPENDIX A – Vicinity & Boring Maps

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APPENDIX B – Boring Log & Lab Reports

Borehole

Number

Milepost ‐ c/l Offset

Depth of

Bore Sample Type Requested Testing

0 to 5"

5" to 11" 2.5' SPT baggy sample Classification

11" to 5' 5 gallon bucket sample Class., R‐Value, pH, Resist.

5' to 14' 10' SPT baggy sample Classification

14'

14' to 17'

17'

14' to 25' 25' SPT baggy sample Classification

0 to 5" 2.5' SPT baggy sample Classification

5" to 10" 5' SPT baggy sample Classification

10" to 5' 5 gallon bucket sample Classification & R‐Value

5'

5' to 15'

15'

15' to 20' 15'+20' SPT baggy sample Classification

0 to 18'

18' 10' SPT baggy sample Classification

18' to 30'

0 to 9"

9" to 12"

12" to 7.5' 2.5'+5' SPT baggy sample Classification

7.5' to 11'

11'

11' to 25' 15' SPT baggy sample Classification

25'

0 to 10"

10" to 14"

14" to 6'

6'

6' to 25' 10' SPT baggy sample Classification

25'

25' to 30' 30' SPT baggy sample Classification

0 to 6"

6" to 11"

11" to 5' 5 gallon bucket sample Classification

5'

5' to 14' 10' SPT baggy sample Classification

14' to 24'

24'

24' to 30' 25' SPT baggy sample Classification

0 to 7"

7" to 12"

12" to 10' 2.5' SPT baggy sample Classification

10'

10' to 14' 10' SPT baggy sample Classification

14'

14' to 20' 15' SPT baggy sample Classification

Note: For each boring, SPTs conducted at 5‐ft intervals with an additional SPT at 2.5‐ft depth (see geotechnical report for SPT data).

groundwater depth permafrost depth brown silty sand with gravel groundwater depth asphalt brown aggregate base brown silty sand with gravel brown silty sand with gravel brown silty sand with gravel tan silty sand with gravel

20' groundwater depth brown aggregate base

30' brown aggregate base

CO FLAP SH5(1) MOUNT BLUE SKY HIGHWAY BORING LOG (September 17‐18, 2020) asphalt

MP 8.87 ‐

5'R

BH 20‐02

Boring Observations

25' brown silty sand with gravel brown silty sand with gravel brown silty sand with gravel brown aggregate base brown silty sand

30' grey silty sand brown aggregate base

MP 9.06 ‐

5'L brown silty sand with gravel asphalt

25' permafrost depth groundwater depth tan silty sand tan silty sand brown aggregate base asphalt tan silty sand with gravel asphalt

BH 20‐10

BH 20‐04

MP 9.10 ‐

20'L

BH 20‐05

MP 9.19 ‐

5'L

MP 9.25 ‐

5'R 30' asphalt brown silty sand with gravel grey silty sand with gravel groundwater depth grey silty sand permafrost depth

BH 20‐08

MP 9.45 ‐

7'R 20' brown silty sand with gravel groundwater depth brown silty sand permafrost depth brown silty sand groundwater depth silty, clayey sand w/ gravel grey clay permafrost depth

BH 20‐07

MP 9.35 ‐

5'L permafrost depth

BH 20‐06

(aka Mount Blue Sky Highway)

APPENDIX C – Site Investigation Photos

MP 8.8 – Looking Ahead Toward Start of Project, East of Upper Parking Lot

Samples of Permafrost and Subgrade Soils from ODEX Drilling

MP 8.85 – Looking Ahead at Location of CDOT’s 2009 Boring with 4.5’ Thick Asphalt

MP 8.85 – Location of CDOT’s 2009 Boring with Thick Asphalt & Localized Overlays

MP 8.87 – ODEX Drilling (Down-hole Air Hammer System) at Boring BH 20-02

MP 8.95 – Location of Large Heave, Possible Large Underlying Boulder

MP 8.98 – Location Looking Ahead at Subsidence & Culvert Thrust through Pavement

MP 9.0 – Looking Ahead at Extensive Subsidence with Inverted Crown / Through Cut

MP 9.06 – Looking Ahead at Subsidence & Boring BH 20-10 at Old Road Alignment

MP 9.10 – Looking Ahead at Monitoring Well / Boring BH 20-04

MP 9.10 – Looking Back from Adjacent to Monitoring Well / Boring BH 20-04

MP 9.10 – Looking Ahead from Adjacent to Monitoring Well / Boring BH 20-04

Looking Ahead at Location of Boring BH 20-05 (MP 9.19) – 90 Feet Beyond Gate

Drilling at Boring BH 20-05 (MP 9.19) – Boring BH 20-06 (MP 9.25) at Center of Curve

MP 9.25 – Looking Back at Boring BH 20-06 near Summit Lake Outlet

Sample of Permafrost from ODEX Drilling

MP 9.35 – Looking Ahead at Boring BH 20-07 and Extensive Longitudinal Cracking

MP 9.35 – Looking Back at Boring BH 20-07 with Large Boulders within Embankment

APPENDIX D – CDOT SH 5 Geotechnical Report (2009)

Memorandum M A T E R I A L S A N D G E O T E C H N I C A L B R A N C H

GEOTECHNICAL PROGRAM

4670 HOLLY STREET, UNIT A, DENVER, COLORADO 80216 303-398-6512 FAX 303-398-6504

SH 5 MM 8.8 to 9.4 Pavement Distress

TO: Russel Cox, Region 1 Foothills Residency

FROM: Steve Laudeman, Geotechnical Program

DATE: September 15, 2009

SUBJECT: Geotechnical Report SH 5 Summit Lake Pavement Distress

INTRODUCTION

The asphalt pavement from MM 8.8 to MM 9.4 on SH 5 near Summit Lake has historically shown severe pavement distress. Discussions with local Maintenance staff indicate the problems have been ongoing for at least several years. This segment of highway is characterized by extreme variations in pavement elevation, on the order of 2 feet over short distances, and poor surface water drainage. In some sections, the centerline of the pavement is lower than the edges, and the entire pavement section is lower than the surrounding ground. The pavement is cracked throughout this segment. In September, 2008, Region 1 Engineering requested an investigation to determine the causes and possible remedies for this problem. Due to the onset of winter weather, the drilling was postponed until the summer of 2009.

INVESTIGATION

A total of five borings were completed for this investigation. Drilling occurred on June 9 and June 17, 2009. Borings B-1 through B-5 were drilled in the southbound lane of SH 5 and were evenly spaced throughout the distress area, with B-1 near MM 8.8 and B-5 near MM 9.4.

Borings were completed using an truck-mounted CME 75 drill rig using hollow stem auger drilling methods. Standard Penetration Testing (ASTM D 1586) was performed at selected intervals in all borings. After completion of drilling, borings B-1, B-2, B-4, and B-5 were completed as temporary piezometers with 1 inch diameter PVC casing. Boring B-3 was backfilled with cuttings. Copies of the logs for each boring are attached to this report.

GEOLOGIC PROFILE

The project site is located adjacent to Summit Lake at an elevation of approximately 13,100 feet.

The topography adjacent to the road is relatively flat and is characterized by the basin of Summit

Lake. Along with Summit Lake, there are several other small ponds and areas of standing water in the area. The vegetation is high alpine tundra with grasses and other low-lying plants growing among cobble- and boulder-size rocks throughout the area. Bedrock outcrops are apparent along the edges of the Summit Lake basin outside of the pavement distress area.

The pavement thickness found at the boring locations varied from approximately 6 inches to 4.5 feet. Beneath the pavement, the borings encountered stiff to hard clay with sand and gravel to depths varying from 9.5 to 23 feet (some of the material encountered during drilling was frozen, so standard consistency descriptions may not apply). In some holes, the clay was underlain by sand with varying amount of clay and gravel to depths of 19 to 21 feet. Two borings encountered apparent weathered bedrock at depths of 19 and 21 feet. Because the drill rig could not penetrate into the apparent bedrock material, bedrock could not be confirmed. All five borings encountered frozen material or ice crystals. The depth at which frozen material or ice was first observed varied from 14 to 19 feet. Decayed vegetation and peat bog material was observed in borings B-3, B-4, and B-5. Laboratory test results for the sample from boring B-3 at a depth of 4 feet show an organic content of 25% by weight. Two samples were tested for swell/consolidation under a 1 ksf applied load. Neither sample showed any significant change in volume upon inundation with water.

Four of the five borings were completed as temporary piezometers. Depth to groundwater has varied with time, as shown in the measurements included in Table 1. In general, depth to groundwater shows an increasing trend with time.

Table 1 - Depth to Water Measurements

Location Date Depth to Water (ft bgs)

6-9-2009 4.2

6-17-2009 3.9 B-1

7-21-2009 6.5

6-17-2009 9.5 B-2

7-21-2009 silted in at 11.2

6-17-2009 0.7 B-4

7-21-2009 2.0

6-17-2009 2.9 B-5

7-21-2009 4.9 Notes: 1. All measurements are in feet below ground surface.

DISCUSSION AND RECOMMENDATIONS

The presence of ice in the soils under the highway suggests that continuous frozen conditions, commonly referred to as permafrost, are present in this high altitude environment. There are several references available regarding design of roadways in permafrost conditions. One useful reference is Department of the Army Technical Manual TM 5-852-3 Artic and Subarctic Construction Runway and Road Design. This document states that "Thawing of previously unthawed subgrades [under paved road surfaces] which have a high ice content ... will result in serious and abrupt surface subsidence." Figure 1 shows a typical cross section under a paved road over permafrost, with the seasonal melted zone substantially deeper under the road than under the adjacent undisturbed areas. Frozen soil has relatively good bearing properties.

Thawed soil, however, has a very high moisture content and very poor bearing properties. The combination of vibration and loading from traffic and saturated soil conditions in the thaw zone leads to settlement of the pavement surface. TM 5-852-3 does not address the anticipated duration of settlement from permafrost thawing. Region 1 Maintenance staff responsible for SH 5 have stated that the pavement distress has been a problem for many years and that there are some sections of the distress area that require the addition of new pavement every year.

Figure 1 - Typical permafrost thaw zone under paved road (from TM 5-852-3)

TM 5-852-3 goes on to recommend that "...thawing of [permafrost] subgrades beneath completed pavements should be prevented by providing sufficient base-course thickness...". Figure 2 shows recommended subgrade thickness related to the thawing index of the pavement surface.

According to TM 5-852-3, the mean surface thawing index for the Colorado central mountains is approximately 8000 degree-days, which suggests a subgrade thickness of over 160 inches, which is not practical. The recommended alternative is design of the pavement section accomodate the anticipated reduction in strength due to subgrade thawing. TM 5-852-3 has a design procedure based on the classification of the subgrade soils based on percent finer than 0.02 mm and anticipated wheel loads. If Region 1 decides to design based on reduced subgrade strength, additional sampling and soil testing may be required, and a detailed pavement design should be performed.

Figure 2 - Required thickness of gravel base (from TM 5-852-3)

Alternatively, some improvement in pavement performance could be accomplished by placing coarse grained subgrade material to the maximum thickness allowed by project budget and site constraints. This material should be Class B Filter Material, incompliance with 2005 CDOT Standard Specifications Section 703.09. This material should be placed to a depth of at least 3 feet below the pavement section. Along with being resistant to changes in volume from freezing and thawing, coarse grained soils are also resistant to capillary action, which can cause water to migrate upwards into the pavement subgrade. The use of geosynthetics in the pavement section may help reduce the severity of future distress. The Geotechnical Program is available to assist in incorporation of geosynthetics into the design. Also, depending on the time of year that construction takes place, frozen ground and/or high groundwater conditions may be encountered and should be considered in the construction planning.

Along with improving the pavement subgrade, improvements to surface and subsurface drainage should be implemented. The presence of shallow saturated conditions under the pavement greatly decreases the bearing capacity of the subgrade soils. A subdrain system should be included in the pavement design to remove excess water from the subgrade. The effectiveness of a subdrain system will depend on the available elevation to promote flow and discharge of the collected water. Also, to improve surface water drainage, the final pavement surface should be above the surrounding natural ground surface as much as possible. The Region 1 Hydraulics engineer should be consulted regarding drainage improvement design for the project.

Since it is not practical to place coarse grained subgrade material to the full depth of anticipated thawing, it is anticipated that there may be future thaw-related settlement of the reconstructed pavement, and the maintenance plan for this highway should include periodic reconstruction of the embankment to correct future settlement.

Please contact this office at 303-398-6512 with any questions regarding the geotechnical engineering for this project.

REVIEW: Hsing-Cheng Liu

COPY: Schiebel, Region 1 Materials Gross, Region 1 Hydraulics Crabdree, Region 1 Maintenance Zufall, Materials and Geotechnical Branch Kotzer, Materials and Geotechnical Branch Liu, Geotechnical Program

4.5 4.5

9.5

18.0

24.5

1A

1B 16-50/4

1C 5-8-7

1D

1E 43-37-50/3

50/5-1/2

50/4

50/5

87/9

3.0

8.0

13.0

18.0

23.0

0 - 4.5 Asphalt pavement

4.5 - 24.5 Clay with sand and gravel, brown, stiff to hard, moist to very moist

4.5 - 5.5 Hard drilling (on rock?)

9.5 - 10.5 Hard drilling (on rock?)

18 - 19.5 clay as above, ice crystals in sample, up to 1/4 inch, angular

23 - 24.5 clay as above, ice in sample

Total Boring Depth 23.0ft

GRAB SHELBY CORE

PROJECT NAME

BORING #

DATE DRILLED

E

LE

V (f t)

COUNTYROUTE

SURVEY INFOTOTAL DEPTH

Laudeman/Blailes

GEOLOGICAL BORING LOG

Clear CreekSH 5

4.2 6/9/2009

10:30

3.9 6/17/2009

13:15

NOTES: CME 75, auger, set 1" piezometer

CON'TSPT

PROJECT ID

Summit Lake Pavement Distress 6/9/09

B-1

SA

WELL

DIAGRAM

23.0ft

H2O DEPTH

DATE

TIME

MM 8.85 (approx)

TOP HOLE ELEV

STRUCTURE/BENT LOCATION

Summit Lake

GEOLOGIST/FOREMAN

LO

G DESCRIPTION

S A

M P

LE

T

Y P

E

D E

P

TH

(f t)

N -V

A

LU

E R

E C

/R

Q D

S A

M P

LE

ID SPT DATA

D E

P

TH

(f t)

5 10 20 40 70

G E

O

LO

G

IC

B O

R

IN

G L

O G

S

U M

M

IT

L A

K E

.G P

J C

O _D

O T.

G D

T

/1 5/

0.5

14.0

19.0

20.5

2A 30-40-21

2B 18-14-16

2C

2D

50/3

50/4

4.0

9.0

14.0

19.0

0 - 6" Asphalt pavement 4 - 14 Clay with sand and gravel, very stiff, brown, sl. moist

14 - 19 Sand, brown, very dense, ice crystals in sample at 14 ft, sample is approx. 60% ice

19 - 20.5 Weathered bedrock, with quartz and mica, frozen Total Boring Depth 20.0ft

GRAB SHELBY CORE

PROJECT NAME

BORING #

DATE DRILLED

E

LE

V (f t)

COUNTYROUTE

SURVEY INFOTOTAL DEPTH

Laudeman/Blailes

GEOLOGICAL BORING LOG

Clear CreekSH 5

9.5 6/17/2009

13:20

NOTES: CME 75, auger, set 1" piezometer

CON'TSPT

PROJECT ID

Summit Lake Pavement Distress 6/9/09

B-2

SA

WELL

DIAGRAM

20.0ft

H2O DEPTH

DATE

TIME

MM 8.95 (approx)

TOP HOLE ELEV

STRUCTURE/BENT LOCATION

Summit Lake

GEOLOGIST/FOREMAN

LO

G DESCRIPTION

S A

M P

LE

T

Y P

E

D E

P

TH

(f t)

N -V

A

LU

E R

E C

/R

Q D

S A

M P

LE

ID SPT DATA

D E

P

TH

(f t)

5 10 20 40 70

G E

O

LO

G

IC

B O

R

IN

G L

O G

S

U M

M

IT

L A

K E

.G P

J C

O _D

O T.

G D

T

/1

0.3

4.0

9.0 9.1

13.0 14.0

3A 10-22-18

3B

3C

50/1

50/1

4.0

9.0

14.0

0 - 4" Asphalt pavement 4" - 14 ft Clay with sand and gravel, some larger rocks, hard

4 - 5.5 Clay as above with organic material,

sl. moist

9 - 10 No recovery on SPT (on rock?)

9 - 11 Very hard drilling

13 Very hard drilling (on rock?)

14 - 15.5 Very low recovery on SPT, frozen sand and gravel (melts in hand) Total Boring Depth 14.0ft

GRAB SHELBY CORE

PROJECT NAME

BORING #

DATE DRILLED

E

LE

V (f t)

COUNTYROUTE

SURVEY INFOTOTAL DEPTH

Laudeman/Blailes

GEOLOGICAL BORING LOG

Clear CreekSH 5

NOTES: CME 75, auger, backfill with cuttings

CON'TSPT

PROJECT ID

Summit Lake Pavement Distress 6/17/09

B-3

SA

WELL

DIAGRAM

14.0ft

H2O DEPTH

DATE

TIME

MM 9.1 (approx)

TOP HOLE ELEV

STRUCTURE/BENT LOCATION

Summit Lake

GEOLOGIST/FOREMAN

LO

G DESCRIPTION

S A

M P

LE

T

Y P

E

D E

P

TH

(f t)

N -V

A

LU

E R

E C

/R

Q D

S A

M P

LE

ID SPT DATA

D E

P

TH

(f t)

5 10 20 40 70

G E

O

LO

G

IC

B O

R

IN

G L

O G

S

U M

M

IT

L A

K E

.G P

J C

O _D

O T.

G D

T

/1

CON'TSPT

PROJECT ID

Summit Lake Pavement Distress 6/17/09

B-4

SA

WELL

DIAGRAM

20.5ft

0.3

9.5

14.5

21.0 21.5

4A 30-50/2

4B 4-3-7

4C 3-4

4D 37-50/4

4E

50/2

CAL

CAL

50/4

50/4

4.5

9.5

14.5 14.6

19.5

21.0

0 - 4" Asphalt pavement 4" - 9.5 ft Clay with sand and gravel, gravel in angular and granitic, up to 1" diam., angular, clay is brown, organic with plant fragments (peat), sl. moist, hard

9.5 - 21 Sand and gravel, some clay, wet, loose, gravel in granitic, angular

14.5 - 15.5 Same as above, sand and gravel, with some ice

21 Weathered bedrock, grey, with quartz and some clay Total Boring Depth 20.5ft

GRAB SHELBY CORE

PROJECT NAME

BORING #

DATE DRILLED

E

LE

V (f t)

COUNTYROUTE

SURVEY INFOTOTAL DEPTH

Laudeman/Blailes

GEOLOGICAL BORING LOG

Clear CreekSH 5

0.7 6/17/2009

13:25

NOTES: CME 75, auger, set 1" piezometerH2O DEPTH

DATE

TIME

MM 9.2 (approx)

TOP HOLE ELEV

STRUCTURE/BENT LOCATION

Summit Lake

GEOLOGIST/FOREMAN

LO

G DESCRIPTION

S A

M P

LE

T

Y P

E

D E

P

TH

(f t)

N -V

A

LU

E R

E C

/R

Q D

S A

M P

LE

ID SPT DATA

D E

P

TH

(f t)

5 10 20 40 70

G E

O

LO

G

IC

B O

R

IN

G L

O G

S

U M

M

IT

L A

K E

.G P

J C

O _D

O T.

G D

T

/1

0.5

4.0

14.0

19.0

20.5

5A 3-3

5B 5-5-6

5C 4-6-7

5D 5-12-22

CAL

4.0

9.0

14.0

19.0

0 - 6" Asphalt pavement 6" - 14 ft Clay with sand and gravel, moist, light brown, stiff

4 - 5 Clay as above with some root fragments

14 - 19 Sand with some clay and gravel, moist, med. dense

19 - 20.5 Clay with sand and gravel, brown to grey, some fine crystalline ice, moist, hard Total Boring Depth 19.0ft

GRAB SHELBY CORE

PROJECT NAME

BORING #

DATE DRILLED

E

LE

V (f t)

COUNTYROUTE

SURVEY INFOTOTAL DEPTH

Laudeman/Blailes

GEOLOGICAL BORING LOG

Clear CreekSH 5

2.9 6/17/2009

13:30

NOTES: CME 75, auger, set 1" piezometer

CON'TSPT

PROJECT ID

Summit Lake Pavement Distress 6/17/09

B-5

SA

WELL

DIAGRAM

19.0ft

H2O DEPTH

DATE

TIME

MM 9.3 (approx)

TOP HOLE ELEV

STRUCTURE/BENT LOCATION

Summit Lake

GEOLOGIST/FOREMAN

LO

G DESCRIPTION

S A

M P

LE

T

Y P

E

D E

P

TH

(f t)

N -V

A

LU

E R

E C

/R

Q D

S A

M P

LE

ID SPT DATA

D E

P

TH

(f t)

5 10 20 40 70

G E

O

LO

G

IC

B O

R

IN

G L

O G

S

U M

M

IT

L A

K E

.G P

J C

O _D

O T.

G D

T

/1

APPENDIX E – Asphalt Binder & Climate Data

Colorado Department of Transportation

2019 Pavement Design Manual

Table 6.9 Recommended SuperPaveTM Gyratory Design Revolution (NDES)

CDOT Pavement

Management System

Traffic Classification

(20 Year Design ESAL)

20 Year Total

18k ESAL in the Design

Lane

High Temperature Category

Very Cool Cool Moderate Hot

Low < 100,000 50 50 50 50

100,000 to < 300,000 50 75 75 75

Medium 300,000 to < 1,000,000 75 75 75 75

1,000,000 to < 3,000,000 75 75 75 100

High 3,000,000 to < 10,000,000 75 75 100 100

Very High 10,000,000 to < 30,000,000 --- --- 100 ---

Very Very High ≥ 30,000,000 --- --- 125 ---

Note: Based on Standard Practice for SuperPave™ Volumetric Design for Hot-Mix Asphalt (HMA), AASHTO

Designation R 35-04.

6.12.3 Binder Selection

Performance graded (PG) binders have two numbers in their designation, such as PG 58-34. Both numbers describe the pavement temperatures in degrees Celsius at which the pavement must perform. The first number (58 in the example) is the high temperature standard grade for the pavement, and the second number (minus 34 in the example) is the low temperature standard grade.

PG 64-28 (rubberized) or PG 76-28 (polymerized) or bituminous mixtures should only be placed directly on an existing pavement or milled surface that does not show signs of stripping or severe raveling. Cores should be taken to determine if stripping is present. Because of a limited number of tanks, Colorado local suppliers only have the capacity to supply a limited number of asphalt cement grades. Table 6.10 Available Asphalt Cement Grades in Colorado shows available grades that maybe used and/or available on CDOT projects.

Table 6.10 Available Asphalt Cement Grades in Colorado

Polymer Modified Unmodified

PG 76-28

PG 70-28

PG 64-28

PG 58-34

PG 64-22

PG 58-28

Note: The Region Materials Engineer may select a different gyratory design revolution for the lower HMA lifts.

APPENDIX F – Design Calculations & Figures robert.norick Text Box robert.norick Callout Average Resilient Modulus for Spring through Fall for Very Good Roadbed Soils is 10,000 psi.

robert.norick Callout The project subgrade has an average R-Value of 73 which corresponds to a Resilient Modulus of greater then 20,000 psi according to PDDM Exhibit 11.4.2.C. Very good soils have an optimum Resilient Modulus of 20,000 psi.

Hydrology and Hydraulics December 2012

Roadway Hydraulics 7-53

Exhibit 7.3-B ESTIMATING STEEL PIPE SERVICES LIFE

FE

D

ER

A L

LA

N

D S

H

IG

H W

A Y

M O

D

IF

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D

C A

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H

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C H

A R

T

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TI

M A

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G S

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C E

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FE

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PL

A

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G

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LV

A N

IZ

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S

TE

EL

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LV

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S er vi ce L ife E st im at io n C ha rt fo r A ve ra ge S er vi ce L ife o f P la in G al va ni ze d C ul ve rts

N

TE

S

1.

Th e cu rv es in th is

C ha rt ar e ba se d on th e da ta in

F H

W A

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LP

-9 1-w hi ch u se s th e fa ct or s in C al ifo rn ia

T es t 6

M et ho d fo r E st im at in g th e

S er vi ce

L ife o f S te el

C ul ve rts

T he se fa ct or s in cr ea se d th e es tim at ed s er vi ce li fe b y a fte r f irs t p er fo ra tio n.

2.

Th

C ha rt ha s al so b ee n m od ifi ed to re fle ct a m in im um m et al th ic kn es s of

.0 in ch o r 1 ga ge [1

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3.

U nd er c on di tio ns w ith p H b et w ee n an d

9, a nd a bo ve

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0, th e av er ag e se rv ic e lif e de te rm in ed fo r p la in g al va ni ze d cu lv er ts s ho ul d be m ul tip lie d by

.0 fo r A lu m in um c oa te d st ee l, (T yp e 2)

TH

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4.

N ot e:

M ul tip ly th e av er ag e Se rv ic e Li fe b y th e Th ic kn es s

Fa ct or

0.

3.

0.

0.

0.

0.

0.

TH

IC

K N

ES

S, in ch

G

A G

E

TH

IC

K

N

ES

S, m

FA

TO

APPENDIX G – Project Specific SCRs

Add the following Section:

Section 308. — RECYCLED AGGREGATE

Description

308.01 This work consists of providing and placing recycled aggregate using material generated from existing pavement structure.

Material

308.02 Conform to the following Subsections:

Water 725.01(c)

Construction Requirements

308.03 General. Establish alignment, profile and cross slope according to Section 152.

Protect manholes, valve covers, and other buried facilities from damage.

Submit a plan to the CO for approval 14 days prior to beginning removal of existing material.

Include in the plan details on removal, processing, handling, storage, quantities, sequencing, mixing and placement locations of the recycled material.

Remove and salvage the existing pavement structure at the location and to the depth shown on the plans. Use equipment meeting the requirements of Sections 304 and 413. Reduce oversize particles to 100 percent passing the 2-inch sieve.

Stockpile material according to Subsection 314.04 and 314.05.

308.04 Preparing Surface. Prepare the surface on which the recycled aggregate base is placed according to Section 303.05.

308.05 Mixing and Spreading. Place recycled aggregate to the limits shown in the plans. Place enough material to bring the final surface to the established line, grade, and cross-section. Mix the recycled aggregate to its full depth. During mixing add water to provide the optimum moisture content for compaction. After mixing, spread to the thickness and cross-section shown on the plans. Do not place the mixture in a layer exceeding 6 inches (150 millimeters). When more than one layer is necessary, compact each layer according to Section 301.05 before placing the next layer.

308.06 Compacting. Compact each lift according to Subsection 301.05

308.07 Surface Tolerance. Finish the surface according to Subsection 301.06.

308.08 Maintenance. Maintain the recycled aggregate according to Subsection 301.07. Overlay the base within 14 days after compacting.

308.09 Acceptance. See Table 308-1 for sampling, testing, and acceptance requirements.

Construction of recycled aggregate base will be evaluated under Subsections 106.02 and 106.04.

Measurement

308.10 Measure the Section 308 pay items listed in the bid schedule according to Subsection

109.02 and the following as applicable.

When measuring recycled aggregate by the cubic yard (cubic meter) or square yard (square meter), measure in place.

Measure removal and disposal of unsuitable material under Sections 203 and 204.

Payment

308.11 The accepted quantities will be paid at the contract price per unit of measurement for the Section 308 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05.

ab le

-1

Sa pl in g, T es tin g, a nd

A cc ep ta nc e

R eq ui re m en ts at er ia l o r

Pr od uc t

(S ub se ct io n) yp of cc ep ta nc e (S ub se ct io n) ha ra ct er is tic at eg or y T es t M et ho ds

Sp ec ifi ca ns pl in g

Fr eq ue nc y Po in t o f Sa m pl in g lit pl e R ep or tin g

T im e R em ar ks

Pr od uc tio n R ec yc le d m at er ia l a ad de d cr us he d ag gr eg at e if ne ce ss ar y

M ea su re d an d te st ed fo r co nf or m an ce

(1

.0

4) oi st ur e-ity

A

SH

0, ho d

D (1 pe r ch ge at er ia l

St oc kp ile

Y es

B ef or e us in g in w k en si ty

A pe r 1, yd

In -p la ce a fte r co m pa ct io n N o En d sh ift

Fo r

M et ho d co m pa ct io n on ly

Pr oc es s co nt ro l

(1

3) oi st ur e co nt en t (in

-p la ce

A

A or o er ap pr ov ed im um pe r

1, yd

U po n co m pl et io n of te st ru sh ag gr eg at e

(7

6) ea su re d an d te st ed fo r co nf or m

G ra da tio n

A A

SH

TO

im um pe r 1, to oa db be fo re m ix in g w ith re cy cl ag gr eg at e

Y h ou rs

Fi ni sh ed

P ro du ct yc le d m at er ia l a ad d ad de d cr us he d ag gr eg at e if ne ce ss ar y

M ea su re d an d te st ed fo r co nf or m

Su rf ac e to le ra nc e g ra bs ec tio n er m by e rf ac fin al c ou rs

N o

B ef or e pl ac em en t of n ex t la ye r o r a s re qu es te d

(1 ) M in im um o f 5 p oi nt s p er p ro ct

Section 403. — ASPHALT CONCRETE

Description

403.01 Add the following:

Use an Asphalt binder that would be specified for the project location and is designated according to AASHTO M 320.

Construction Requirements

403.02 Composition of Mix (JMF). Delete the subsection and substitute the following:

403.02 Composition of Mix (JMF).

Conform to current state department of transportation material specifications for asphalt concrete. Submit a state department of transportation JMF approved within the past 12 months for approval at least 30 days before production that meets the current state department of transportation requirements for the location and type of facility being constructed. For each proposed JMF, submit a production certification conforming to state department of transportation specifications. Submit the strength, quality, and gradation specifications for the asphalt concrete mix. Include copies of laboratory test reports that demonstrate aggregate, asphalt binder, additive, and mix properties meet state department of transportation specifications. Submit the maximum specific gravity (density) of the mix as determined by AASHTO T 209. When requested, submit a representative 100 pound loose mix sample 21 days prior to placement. See Table 403-2 for Type I and Type II sampling, testing, and acceptance requirements.

403.08 Placing and Finishing.

(a) Add the following:

Use an MTV with storage and remixing capabilities on all mainline construction for placing asphalt concrete mixtures. The MTV will independently remix and deliver mixture from the hauling equipment to the paving equipment.

Furnish an MTV with the following:

(1) Independently operated with its own driver/operator;

(2) Independent from the paver;

(3) A loading system with the ability to receive mixtures from hauling equipment;

(4) A minimum storage capacity of 15 tons (13.6 metric tons) with a remixing system in the material storage bin;

(5) Remixing capability within the storage bin;

(6) A discharge conveyor to deliver the mixture to the paver hopper; and

(7) A mass not exceeding the maximum legal loadings on structures.

Pick-up machines, hopper inserts, and material transfer devices are not considered MTVs.

In the event the MTV malfunctions during paving operations, the Contractor must suspend paving, however mix in transit and stored in the silo at the time of breakdown may be placed without the use of an MTV. Do not resume mix placement until the MTV is operational.

403.09 Compacting. Add the following:

For HMA, do not roll the mix after the surface cools below 175 ºF (80°C).

Along forms, curbs, headers, walls, and other places not accessible to the rollers, compact the mix with alternate equipment to obtain the required compaction.

403.12 Acceptance. Add the following:

During production placement of the mix, sample loose mix and compacted cores according to Table 403-2 and submit to the CO for acceptance. Materials that do not meet the approved job-mix formula are considered unacceptable.

Delete Table 403-2 and substitute the following:

Table 403-2

Sampling, Testing, and Acceptance Requirements

Material or Product

(Subsection)

Type of Acceptance (Subsection)

C ha ra ct er t M et ifi ca

Sampling Frequency

Point of Sampling Sp pl e

Reporting Time

R em

Mix Design Asphalt concrete mixture Type I

(403.02(a))

Measured and tested for conformance (106.04)

Job-mix formula

Subsection 403.02(a)

When requested by the CO.

Flowing mix stream (bin or belt discharge) or behind the paver before compaction.

Yes Before approval of job-mix formula

Tested by the

CO

Production Asphalt concrete, Type I

(403.02(a))

Measured and tested for conformance (106.04)

Job-mix formula

Density (1)

Maximum specific gravity

Subsection 403.02

AASHTO

T 166

AASHTO

T 209 (2)

1 per 700 tons

(650 metric tons)

Behind the paver before compaction.

In-place after Compacting

Behind the paver before compaction

Yes

24 hours

Deliver cores to

CO

for testing

Surface Tolerance

Straightedge Measurement, Subsection

403.11

Continuously, after compaction

Finished pavement surface

No “

Placement temperature

− First load and as determined by

CO thereafter

Hauling vehicle before dumping, or windrow before pickup

No Upon completion of measurement

Table 403-2 (continued) Sampling, Testing, and Acceptance Requirements

Material or Product

(Subsection)

Type of Acceptance (Subsection)

C ha ra ct er t M et ifi ca

Sampling Frequency

Point of Sampling Sp pl e

Reporting Time

R em

Production Process control (153.03)

Gradation at the plant

AASHTO

T 27 & T 11

Contractor determined

Cold feed or hot bins as applicable

No 24 hours

Moisture content of aggregates

AASHTO

T 255

" Stockpile No " −

Density ASTM D2950

1 per 500 feet

(150 meters)

In-place after compacting

No " −

Asphalt concrete, Type II

(403.02(b))

Measured and tested for conformance

(106.04)

" " 3 per 700 tons

(650 metric tons)

In-place after compacting

No " −

(1) Dry cores to constant mass at 125±5°F (52±3 °C) or vacuum dry, ASTM D7227 before testing. For asphalt concrete Type I, cut two 6-inch (150-millimeter) diameter side by side cores. Remove them with a core retriever and fill and compact the core holes with asphalt concrete mixture. Label the cores and protect them from damage due to handling and temperature. Submit one core for verification testing. Dry the other core to constant mass at 125±5 °F (52±3 °C) or vacuum dry it according to ASTM D7227 before performing the core density and measuring the thickness. Use

62.245 pounds per cubic foot (997.1 kilograms per cubic meter) to convert specific gravity to density. Use AASHTO T 166 regardless of the volume of water absorbed. Use the average maximum specific gravity value (AASHTO T 209) of the first three samples to determine the percent compaction of each Lot.

(2) Do not use the dry back method (Section 11…