HOT MIX ASPHALT TESTING TECHNICIAN - cttp MIX ASPHALT TESTING TECHNICIAN ... If an asphalt core has a specific gravity of 2.335, ... Allowable Field Tolerances 5.1 % to 5.7 % 3.0 %

2018

1

HOT MIX ASPHALTTESTING TECHNICIAN

developed by:The University of Arkansas, Dept. of Civil Engineering

in conjunction withThe Arkansas Department of Transportation

Refresher Info

Sampling / Reduction

Design / Volumetrics

• ARDOT Specifications

• Calibrations

Gyratory Compaction

Gmb / Gmm• % Air Voids & % VMA

% Binder• AC Gauge • Ignition Oven

% Compaction• Cores • Nuclear Density

COURSE OVERVIEW

2018

2

Written Exam• ≈ 60 Questions

• Closed Book Exam• 2 Hour Time Limit

• 70 % Overall to Pass

Results• www.cttp.org

• Letter & Certification

Performance Exam

• 6 Exam Stations

• Gyratory Compactor

• Bulk SpG (Gmb)

• Max SpG (Gmm)

• Ignition Oven

• AC Gauge

• Density Gauge

TEST DAY

BASIC AGGREGATES CERTIFICATION RENEWAL

Certification Expires Dec. 31, 2022To prevent expiration :

• Take online Basic Aggregates Certification Renewal course during 2022

• Pass online test for Basic Aggregates Certification Renewal course during 2022

• Cost - $0 (none)

• Extends Basic Aggregates Certification through 2027

If not completed prior to Jan. 1, 2023, other ARDOT certifications will be revoked

• Soils, Hot-Mix Asphalt, Concrete, Concrete Strength

2018

3

1 lb = 453.6 g

1 ton = 2000 lb

1 yd² = 9 ft²

1 station = 100 ft

CONVERSIONS

TERMINOLOGY

Terms and formulas relating to mix design and acceptance testing for asphalt mixtures and

pavements

2018

4

TERMINOLOGY

HMA - Hot Mix Asphalt (Binder & Aggregate)

Binder – An asphalt-based cement produced from petroleum residue with or without modifiers (AR PG Grades 64-22, 70-22, 76-22)

Aggregate – A granular material (sand, crushed stone or gravel, steel slag). May refer to an individual aggregate type or to the blend of several different aggregates

TERMINOLOGY

Nominal Maximum Aggregate Size (NMAS)• Superpave : One size larger than the first sieve that

retains more than 10% aggregate

Maximum Aggregate Size (MAS) • Superpave : One size larger than the NMAS

The NMAS is the designated size of an ARDOT asphalt mix design

• (9.5 mm, 12.5 mm, 25.0 mm, 37.5 mm)

2018

5

TERMINOLOGY

X Y Z

(quantity) (material) (type)

G : specific gravity a : air a : absorbed

W : weight (mass) b : binder b : bulk

V : volume s : stone (agg) e : effective

P : percent m : mix m : maximum

Gb - SpG of the binder Gmb - Bulk SpG of the mix

Xyz

Mix Design

• Determines the blend which will produce the required properties

• AASHTO R 35

• ASSHTO M 323

• ARDOT Specifications

Field Testing (QC/QA)

• Determines compliance with ARDOT specifications based on the approved mix design

TERMINOLOGY

Mix design is separate from field testing. However, many terms and calculations are the same!

2018

6

TERMINOLOGY

Ps + Pb = 100 %

%

%

ARDOT bases the % binder on the total mix weight

=+

Agg Wt. + Binder Wt. = Mix Wt.

TERMINOLOGY

What is the Ps if the Pb = 5.6 % ?

%

% . % . %

Report Ps & Pb to the nearest 0.1 %

2018

7

TERMINOLOGY

Specific Gravity (G)

• Relative density to water

• How many times lighter or heavier than water an object is

Density (D). / ³

G = 2.336D = 145.8 lb/ft³

4500 g

1926 gG = 1.000D = 62.4 lb/ft³

Report density to the nearest 0.1 pcf

TERMINOLOGY

If an asphalt mixture has a specific gravity of 2.428, what is the density (lb/ft³) of the mixture?

. / ³

. . .

151.5 lb/ft³

2018

8

TERMINOLOGY

If an asphalt core has a specific gravity of 2.335, what is the density (lb/ft³) of the core?

Specific Gravity of Binder (Gb)

• Mix Design

• 77 °F

• Field Testing

• 77 °F or 60 °F

• 77 °F is used for all calculations

Conversion

.

What is the Gb77for binder

with a Gb60= 1.025 ?

. .. .

TERMINOLOGY

Report all specific gravities to the nearest 0.001

2018

9

TERMINOLOGY

Bulk Specific Gravity of the Mixture (Gmb)

• Specific gravity of a compacted asphalt mixture

• Used to determine the volumetric properties of compacted mixes relative to the Gmm

A = dry weightB = SSD weightC = submerged weight


TERMINOLOGY

Determine the Gmb of the compacted specimen

Dry Weight 4556.7Submerged Weight 2621.0SSD Weight 4563.5

ACB

.. .

.

..

2.346

2018

10

TERMINOLOGY

Determine the Gmb of the compacted specimen

Dry Weight 2327.2Submerged Weight 1398.6SSD Weight 2332.0

TERMINOLOGY

% Absorption (% Abs)

• The percentage of water absorbed by the specimen based on the volume of the specimen

• If Gmb is determined using AASHTO T 166 (Bulk Specific Gravity) and the absorption of the specimen is > 2 %, the test results for Gmb are not valid and an alternative test method (AASHTO T 275 or AASHTO T 331) must be used

% %A = dry weightB = SSD weightC = submerged weight

Report % absorption to the nearest 0.01 %

2018

11

% Absorption

%

Dry Wt (air) = 4573.6 g

SSD Wt (air) = 4585.1 g

Sub. Wt = 2633.0 g

TERMINOLOGY

%. .. .

%..

% . %

0.59 %

A

B

C

TERMINOLOGY

Determine the % absorption of the compacted specimenDry Weight 4558.3Submerged Weight 2631.2SSD Weight 4571.0

2018

12

TERMINOLOGY

Max. Theor. Specific Gravity of the Mixture (Gmm)

• Specific gravity of an asphalt mixture with no air voids

• Used to determine the relative density and % compaction of compacted asphalt mixtures

A = dry weightC = submerged weight


TERMINOLOGY

Determine the Gmm of the asphalt mixture

Dry Weight 1786.4(Pyc + S) Sub Weight 2348.7(Pyc) Sub Weight 1300.0

A

.. .

..

.

2.422

C = 1048.7

2018

13

TERMINOLOGY

Determine the Gmm of the asphalt mixture

Dry Weight 2833.3(Pyc + S) Sub Weight 2961.1(Pyc) Sub Weight 1301.2

TERMINOLOGY

Relative Density (% Compaction)

• Density of a mixture relative to a standard

• Maximum Theoretical Density or Specific Gravity

% %

Gmm100 %

Gmb96 %

Report % compaction to the nearest 0.1 %

2018

14

TERMINOLOGY

Determine the % compaction

Gmb of Core 2.329Gmm of Mix 2.428

% %

%..

% . %

95.9 %

TERMINOLOGY

Determine the % compaction

Gmb of Core 2.358Gmm of Mix 2.502

2018

15

TERMINOLOGYAir Voids (Va)

(volume of air between coated aggregate particles)

Stone(Aggregate)

Voids in the Mineral Aggregate (VMA)

(volume of air voids + volume of effective asphalt coating)

Binder(asphalt cement)

TERMINOLOGY

% Air Voids (Va)

• Volume of air pockets in a compacted asphalt mixture

% %

Gmm100 %

Gmb96 %

Va = 4 % Va = 0 %

% % %

2018

16

TERMINOLOGY

Find the reported % air voids

Gmb 1 2.363 Gmm 2.447Gmb 2 2.367

% %

%..

% % . % . %

3.4 %

% Compaction

Average Gmb 2.365

Report % air voids to the nearest 0.1 %

TERMINOLOGY

Find the reported % air voids

Gmb 1 2.305 Gmm 2.413Gmb 2 2.303

2018

17

TERMINOLOGY

Effective Specific Gravity of the Aggregate (Gse)

• Specific gravity of the aggregate including the volume of pervious pore spaces not filled with asphalt


TERMINOLOGY

Determine the Gse of the mixture

Pb 5.7 %Gmm 2.413Gb77

1.032

100% 5.7% 94.3%

.

...

.. … . …

..

.

2.625

2018

18

TERMINOLOGY

Determine the Gse of the mixture

Pb 4.2 %Gmm 2.555Gb60

1.032

TERMINOLOGY

Voids in the Mineral Aggregate (VMA)

• Volume of air voids and effective asphalt coating in an asphalt mixture

%

%

Report % VMA to the nearest 0.1 %

2018

19

TERMINOLOGY

Calculate the % VMA for the mixture

Gmb 1 2.305 Pb 6.0 % VMACF 1.8 % Gmb 2 2.303 Gse 2.612

%

%. . %

.% . % . %

. % . % . %

Average Gmb 2.304Ps 94.0 %

TERMINOLOGY

Calculate the % VMA for the mixture

Gmb 1 2.425 Pb 4.6 % VMACF 0.5 % Gmb 2 2.431 Gse 2.635

2018

20

ARDOT ACHM MIX DESIGNS

Relationships between ARDOT

asphalt mix designs and field acceptance

testing and quality control

ACHM MIX DESIGN

ARDOT ACHM Mix Designs are approved for a period of 5 years provided that the mix design produces satisfactory

results during production and placement

2018

21

Mix Design Properties

Optimum Asphalt Binder : 5.4 %

Air Voids : 4.0 %

VMA : 14.5 %

VFA : 73.1 %

Fines to Asphalt Ratio : 0.99

Retained Stability : 96.1 %

Nmax : 205

Asphalt Binder : Hog Oil PG 76-22

APA Results : 1.055 mm

Allowable Field Tolerances

5.1 % to 5.7 %

3.0 % to 5.0 %

13.5 % to 16.0 %

5.000 mm or less

ACHM MIX DESIGN

Page 1 of ARDOT Mix DesignMix Design Number : HM000-14

ACHM MIX DESIGNNo. Aggr. ID Aggr. Name Source Location

1 Hog7500 ¾” Chip Hogville Group, Hog Quarry Fayetteville, AR

2 Hog5000 ½” Chip Hogville Group, Hog Quarry Fayetteville, AR

3 Hog3750 3/8” Gravel Hogville Group, Hog Sand & Gravel Fayetteville, AR

4 Hog2200 Ind. Sand Hogville Group, Hog Quarry Fayetteville, AR

5 Hog2000 Screenings Hogville Group, Hog Quarry Fayetteville, AR

Sieve Size 1 2 3 4 5 Job Mix Control Points

19 100 100 100 100 100 100 100 %

12.5 74 100 100 100 100 95 90 – 100 %

9.5 47 91 100 100 99 87 90 % Max

4.75 5 21 96 94 80 54

2.36 3 3 76 65 61 36 28 - 58 %

1.18 3 3 51 43 49 26

0.6 3 3 32 25 41 18

0.3 3 3 17 16 32 12

0.15 2 2 8 14 22 8

0.075 1.5 1.0 3.5 10.0 12.0 4.6 2 – 10 %

Cold Feed % 20 29 22 15 14

Gsb 2.520 2.616 2.559 2.496 2.544

Page 2 of ARDOT Mix Design

2018

22

ACHM MIX DESIGNDesign Summary

Mix Design #: HM000-14 Mix Type : 12.5 mm ACHM Surface

Total Asphalt Content %: 5.40 % Air Voids (Va): 4.0

VMA: 14.7

Max. Theor. SG (Gmm): 2.400 VMA Corr. Factor: 1.5

Asphalt Binder: PG 76-22 Gsb: 2.556

Asphalt Binder Source: Hog Oil Company Gse: 2.601

Mixing Temp (F): 340 Gse: 2.601

Compaction Temp (F): 310 Gb: 1.020

Antistrip Source: N/A

Antistrip %: 0 Ni: 9

% Retained Stability: 96.1 Nd: 125

Nm: 205

Loaded Wheel Test (LWT) Data (mm) = 1.055 Spec Max = 5.000 mm

Page 3 of ARDOT Mix Design

ARDOT SPECIAL TESTS

Tests required at the start of production for a new mix design and in the event of a 90 day or more interruption in mix production

2018

23

Plant Set

• Mix Design %

• Cold Feed %

• Opt. % Binder

Verify

• % Air Voids & % VMA

• % Binder & Gradation

After Verification

• Aggregate proportion adjustments can be made

• ≈ 5% per bin limit

• 10% total adjustment

• May submit as field design to Engineer

FIELD VERIFICATION OF ACHM

TEST METHOD FOR WATER SENSITIVITY FOR COMPACTED

BITUMINOUS MIXTURESAHTD 455 A

Uses gyratory compacted specimens to evaluate the effects of water and temperature on the strength of asphalt mixtures

Stripping

2018

24

Mix Design Requirement

• Mix must retain ≥ 80 % strength

Field Requirement

• Mix must retain ≥ 70 % strength

TEST FOR WATER SENSITIVITYAHTD 455 A

Stripping

When • Once during 1st

three days of production

• After 90 day interruption

Breaking Heads • Use Lottman head if

stability >10,000 lb

Equipment


Standard Lottman

2018

25

Specimens

• (4) 6” Gyratory Specimens

• Approximately 3 ¾” high (95 mm)

• ≈ 1000 g less than full size specimen

• Compact to Ndesgyrations


Group A

• Submerge in water bath 30 - 40 min

• 140° ± 1.8°F

• Remove from water and immediately break (30 s)

• Record stability (lb) and flow (0.01 in)

Group B• Within 24 hours,

vacuum for 1 hour @ 30mm Hg

• Submerge in 140°F water bath for 24 hours

• Remove and break

• Record stability (lb) and flow (0.01 in)


% . %

2018

26

BATCHING & MIXING ASPHALT MIXTURES

AHTD 449 A

Batching is used to blend aggregates and binder together in a controlled manner to produce specific properties or duplicate a mix design

Careful batching produces repeatable results!

Mix Designs

Calibrations• Ignition Oven

• AC Gauge

Requirements• % Binder

• Cold Feed %

BATCHING

2018

27

Collect binder samples• Manufacturer

• PG Grade

Collect representative stockpile samples

• Oven dry all aggregates

• Fractionate if needed

Determine the size of sample to be batched

• See specification

Determine the number of “points” to be batched

• See specification

BATCHING

BATCHING

Aggregate Weight (10,000 g)

Aggregate %

3/4” Chip 20

1/2” Chip 33

3/8” Gravel 22

Ind. Sand 18

Nat. Sand 7

Weight

(0.20)(10,000) = 2,000

(0.33)(10,000) = 3,300

(0.22)(10,000) = 2,200

(0.18)(10,000) = 1,800

(0.07)(10,000) = 700

Total = 100 Total = 10,000

2018

28

BATCHING

Determine the aggregate batch weights if the required total aggregate weight is 8,000 g.

Aggregate %

3/4” Chip 30

1/2” Screen 28

1/4” Screen 25

Ind. Sand 17

BATCHING

Mix Weight (1,700 g) Pb (6.0 %)

Material %

Binder 6.0

Weight

(0.06)(1,700) = 102

Ps (94.0%)

Total = 100 Total = 1,598.0

Aggregate 94.0

3/4” Chip 36

1/2” Chip 40

Ind. Sand 24

(0.94)(1,700) = 1,598.0

(0.36)(1,598) = 575.3

(0.40)(1,598) = 639.2

(0.24)(1,598) = 383.5

2018

29

BATCHING

Calculate the batch weights for the asphalt mixture if the desired mix weight is 3,300 g and the binder content is to be 5.2%.

Aggregate %

3/4” Chip 35

1/2” Chip 32

Ind. Sand 33

Batch out # of points required

• Include “butter batch”

Preheat aggregate and binder in oven to mixing temperature

• Place binder in oven ≈ 1-2 hours prior to mixing

Preheat tools and mixing bucket

• Clean and / or “butter” mixing bucket

• Buttering prevents a low binder content in the first batch

MIXING

2018

30

Tare out mixing bucket • Scales must be

readable to the nearest 0.1 g

Place aggregate batch into bucket

Prepare “crater”

MIXING

0.0 g

Record weight of aggregate in bucket

Determine mix weight or weight of binder to be added

Add binder to bucket

MIXING

%

2018

31

MIXING

Determine the mix weight or binder weight needed for a calibration point. The Pb = 5.6 % and the measured weight of aggregate in the mixing pot is 7998.2 g.

% . % . %

.

. % % .

. . .

MIXING

Determine the mix weight or binder weight needed for a calibration point. The Pb = 5.0 % and the measured weight of aggregate in the mixing pot is 7996.5 g.

2018

32

Adjust to exact weight of binder

Mix thoroughly

MIXING

MIXING

Empty mixing bucket into a sample container • Use spatula or spoon to clean out all material

Verify bucket weight is within ± 5 g of initial weight bucket

• If not, scrape until weight is within tolerance• Reheat bucket if necessary

Add all scraped out material to sample container

2018

33

MIXING RAP/RAS

Remove heated aggregate sample from oven

Add unheated RAP

Place sample back into oven for 1 hour at mixing temperature

Remove sample from oven and add RAS

Add binder and mix thoroughly

RAP – reclaimed asphalt pavement RAS – reclaimed asphalt shingles

CALIBRATIONS

Good calibrations require batching and mixing accurately

Errors made during calibration will create inaccurate field testing results

2018

34

CALIBRATION OF ASPHALT CONTENT GAUGE TROXLER 3241‐C

AHTD 449A

An AC gauge calibration establishes a calibration curve that correlates count values detected by the gauge to the % binder in the asphalt mixture.

In field testing, the gauge compares the calibration curve to the field test counts and returns the appropriate % binder.

Calibrations

• Gauge specific

• Mix design specific

Calibrations should be done at the expected location of testing

CALIBRATION OF AC GAUGEAHTD 449A

2018

35

Equipment

• AC Gauge

• Sample Pans (3+)

• Scales

• Readable to 0.1 g

• Capacity ≥ 12,000 g

• Leveling Plate

• ≥ ¾’’ Plywood

• ≥ ½’’ Plexiglass

• ≥ 0.4’’ Metal Plate

• Thermometer

• 50 – 500 °F


Batch Calib. Points

• 4 points required

• 8000 g aggregate

• Includes weight of RAP and RAS

Mix Points

• Example: Opt. = 6.2 %

• Point 1 @ 5.2%

• Point 2 @ 6.2 %

• Point 3 @ 7.3 %

• Point 4 @ 0.0%

Return mixed samples to oven to maintain temperature


Dry Batch 0 %

Design - 1 %

Design Optimum

Design + 1 %

2018

36


Adjust oven temperature to calibration temperature

• Choose temperature of 200 - 300 °F

• Field testing is ≈ ± 10 °F of calibration temperature

Prepare “blank” pan• Tare pan or record empty

weight of pan


Fill sample pan with dry aggregate in 2 layers

• 1st Layer

• Add aggregate until pan is ≈ half full

• Tamp aggregate and work corners with scoop or spoon

• Drop pan ≈ 1 inch onto hard surface

• 2nd Layer

• Add aggregate until just over full

• Tamp aggregate and work corners

2018

37

Level the top surface with a straight edge

Determine the net weight of aggregate to nearest whole gram

CALIBRATION OF AC GAUGE AHTD 449A


1. Record net weight of aggregate.2. Dump aggregate back into original pan with remaining

aggregate. Remix by turning aggregate over a minimum of three times using scoop.

3. Fill pan a second time and record net weight of aggregate.

4. Repeat filling and weighing steps until two consecutive tries are within ± 25 g of each other.

5. Use the last weight as the calibration net weight.

This is the net weight used for all remaining samples!

2018

38

Prepare Asphalt Samples

• Tare pan

• Fill pan in two layers

• Work corners with scoop

• Overfill pan on top lift

• Adjust weight to = net weight of dry sample (± 5 g)

• Use leveling plate to compress sample into pan


Repeat for the remaining samples

• Optimum

• Optimum ± 1%

Place sample pans in oven to retain temperature

• Do not reheat asphalt samples


DRY

+ 1 %OPT.

- 1 %

2018

39

Turn on gauge and allow to warm up

Check chamber to make sure it is clean and empty

Keep chamber door closed during operation


- GAUGE READY -11:11 11/28Time : 4 minutesCalib# 12.5

YES NO/CE

STORE PRINT

CALIB TIME

SHIFT BKG

9

1

4

7

2

5

8

0

6

3

.START/ENTER

Change time (16 min)

▼ TIME

▼ YES

▼ 4 (16 min)


YES NO/CE

STORE PRINT

CALIB TIME

SHIFT BKG

9

1

4

7

2

5

8

0

6

3

.START/ENTER

- Count Time -4 min.

Do you wantto change?

Sel : 1 - 1 min. 2 - 4 min.3 - 8 min.4 - 16 min.

2018

40

Begin calibration

▼ CALIB

▼ 3 (New Calib.)

▼ 1 (Sample Pan)


YES NO/CE

STORE PRINT

CALIB TIME

SHIFT BKG

9

1

4

7

2

5

8

0

6

3

.START/ENTER

Calib # 12.5 1 - Review Calib.2 - Stored Calib.3 - New Calib.

CALIB. TYPE Select :

1 - Sample Pan2 - Plug Pan

▼ 2 (Gauge derived)

▼ YES


YES NO/CE

STORE PRINT

CALIB TIME

SHIFT BKG

9

1

4

7

2

5

8

0

6

3

.START/ENTER

Select source for New Calib.

1 - Keypad input2 - Gauge derived

Background : 2022 Time : 16 minutes

Want to take anew background?

2018

41

▼ START

▼ YES


YES NO/CE

STORE PRINT

CALIB TIME

SHIFT BKG

9

1

4

7

2

5

8

0

6

3

.START/ENTER

Empty chamber & Press START for

16 minuteBackground count

New Background count = 2035

Want to use thenew count ?

▼ Weight ▼ ENTER

▼ 3 ▼ ENTER


YES NO/CE

STORE PRINT

CALIB TIME

SHIFT BKG

9

1

4

7

2

5

8

0

6

3

.START/ENTER

Blank sample Net WT : _______ g

Input andPress ENTER

How many samples (2 – 12)? ___


2018

42

▼ % AC ▼ ENTER

▼ START


YES NO/CE

STORE PRINT

CALIB TIME

SHIFT BKG

9

1

4

7

2

5

8

0

6

3

.START/ENTER

- Sample # 1 -%AC : _______%


Load sample # 1 Close door

& Press STARTTime : 960 sec.

Record Counts

▼ ENTER

Repeat process for all calibration points


Counts : 2910

Press ENTER

2018

43

Working

▼ YES

▼ 1 (Screen)


YES NO/CE

STORE PRINT

CALIB TIME

SHIFT BKG

9

1

4

7

2

5

8

0

6

3

.START/ENTER

Fit coeff : 0.999 Want to review

input data?

Select method of viewing data :

1 - Screen2 - Printout

≥ 0.995

▼ YES

▼ YES (record)

▼ YES

▼ YES


- Review Data -Weight : 6901g

Background : 2022(Press YES)

A1 : -6.014918A2 : 3.890560A3 : 0.000000000

(Press YES)

# 1 : 5.300%ACCounts: 2910Diff = -0.007%AC

(Press YES)

# 2 : 6.300%ACCounts: 3162Diff = 0.013%AC

(Press YES)

2018

44

▼ YES

▼ YES

▼ YES

▼ MIX # ▼ ENTER


# 3 : 7.300%ACCounts: 3424Diff = -0.006%AC

(Press YES)

Fit coeff : 0.999Do you want toActivate thisCalibration ?

CalibrationActivated !

Want to store Calibration ?

Calibration # ?________

Input and Press ENTER

Gauge is now calibrated and ready for use

Run 16 min. “blank” sampleRecord counts

Dry counts may be used to check for changes in aggregateRecord calibration data

• Gauge #

• Mix Design Number

• Net Sample Weight

• Test Temperature

• Fit Coefficient

• Calibration Information


- GAUGE READY -1:00 11/28Time : 16 minutesCalib# 2008

2018

45

2 Point Calibration

Fit Coefficient = 1.000

ALWAYS, Even if wrong

% AC Counts

5.0 2900

7.0 3580


5

5.5

6

6.5

7

2800 3000 3200 3400 3600%

Pb

Counts

3 Point Calibration

Fit Coefficient ≈ 0.998

Straight line fit

% AC Counts Diff.

5.0 2900 -0.017

6.0 3120 0.017

7.0 3580 -0.016


5

5.5

6

6.5

7

2800 3000 3200 3400 3600

% P

b

Counts

2018

46

3+ Point Calibration

Fit Coefficient ≥ 0.999Curved fit

% AC Counts Diff.

5.0 2900 -0.002

5.5 3000 0.001

6.0 3120 -0.001

6.5 3300 0.001

7.0 3580 -0.002


5

5.5

6

6.5

7

2800 3000 3200 3400 3600%

Pb

Counts

DETERMINING THE ASPHALT BINDER CONTENT OF HOT MIX

ASPHALT (HMA) BY THE IGNITION METHOD

AASHTO T 308

Calibration : Establishes correction factors for binder content and aggregate breakdown

2018

47

Correction factors are mix design and ignition oven specific

• > 5% change in mixture proportions requires a new calibration

Equipment

• Ignition Oven

• Specimen Basket

• Catch Pan

• Scales

• Readable to 0.1 g

IGNITION OVEN CALIBRATIONAASHTO T 308

Samples• All samples are

laboratory batched using oven dried aggregate (JMF)

• AASHTO T 30

• Mix all samples with asphalt using the optimum % binder from the mix design

Samples may notexceed minimum mass by more than 500g


NMASMinimum Mass (g)

# 4 1200 g3/8” 1200 g1/2” 1500 g3/4” 2000 g

1” 3000 g1 ½” 4000 g

2018

48


Binder Correction Factor

• Batch and mix 2 samples at the design % binder

• Turn ignition oven on and input required data

• Set chamber temperature to 538 °C

• Set calibration factor to 0.00

• Allow oven to reach chamber set point temperature

Burn Samples

Record Data

• Binder content from the printed ticket (Calib. Asphalt Ctnt)

• Save sample remains for aggregate CF

Elapsed Time : 57:21

Sample Weight : 1838g

Weight Loss : 116.3g

Percent Loss : 6.32 %

Temp Comp : 0.16 %

Calib. Factor : 0.00 %

Calib. Asphalt Ctnt 6.16 %

Filter Set Pt : 850°C

Chamber Set Pt : 538°C


2018

49


Compare Burned Calibration Samples• Sample 1 – 6.16 % @ 538°C

• Sample 2 – 6.20 % @ 538°C

If difference ≤ 0.15 %• Compute a correction factor (CF)

If difference > 0.15 %• Burn two more samples @ 538°C

• Throw out high and low values

• Compute a correction factor (CF)

0.04 % Difference

CF is the difference between the actual

and measured binder contents


Difference ≤ 0.15 % Design % = 6.0 %

• Sample 1 – 6.16 % @ 538°C

• Sample 2 – 6.26 % @ 538°C

Compute a correction factor (CF)

Average = 6.21 %

CF = 6.21 % - 6.00 % = 0.21 %

CF = 0.21 %

Diff. = 0.10 %

Report binder correction factors to the nearest 0.01 %

2018

50


Difference > 0.15 % Design % = 6.0 %

• Sample 1 – 6.16 % @ 538°C

• Sample 2 – 6.32 % @ 538°C

Burn two more samples

Throw out high an low values

• Sample 3 – 6.24 % @ 538°C

• Sample 4 – 6.35 % @ 538°C

Throw out!

Keep!

CF = 0.28 %Average = 6.28 % 6.28 % - 6.00 % = 0.28 %

Diff. = 0.16 %


If Correction Factor ≤ 1.0 % (538°C)

• Report CF

If Correction Factor > 1.0 %

• Start over but burn samples at 482°C

• Report CF even if > 1.0 % if established at 482°C

• If there is no improvement in the CF at 482 °C, you may use the CF from the higher temperature

2018

51


Determine the CF

Pb = 5.3 %

Sample 1 5.37 % @ 538 °C

Sample 2 5.40 % @ 538 °C


Determine the CF

Pb = 5.5 %

Sample 1 5.57 % @ 538 °C

Sample 2 5.78 % @ 538 °C

Sample 3 5.66 % @ 538 °C

Sample 4 5.80 % @ 538 °C

2018

52


Determine the CF

Pb = 6.4 %

Sample 1 7.92 % @ 538 °C

Sample 2 7.96 % @ 538 °C

Sample 3 6.66 % @ 482 °C

Sample 4 6.80 % @ 482 °C


Aggregate Correction Factors (ACF)

• Batched Samples

• (1) “Blank” Sample

• (2) Burnt Ignition Oven Samples

• Wash samples over # 200 sieve

• Use wetting agent

• Sieve samples

• Report % passing to nearest 0.1% for all sieves

2018

53


Compute ACF for each sieve

• Average gradations for burned samples

• Subtract average gradation from “blank” gradation

.

Report aggregate correction factors to the nearest 0.1 %

Determine application of aggregate correction factors

• If any sieve (except #200) exceeds the allowable difference

• Apply correction factors to all sieves

• If only the # 200 sieve exceeds the allowable difference

• Apply only the #200 correction factor

Round and report sieve analysis

SieveSizes

Allow.Diff.

# 8 & Up ± 5.0%

> # 200 & < #8 ± 3.0%

# 200 ± 0.5%


2018

54


Find the ACF and which ones need to be applied

Sieve BlankBurn #

1Burn #

2Avg. Burn

ACFAllowableDifference

1/2” 100.0 100.0 100.0 ± 5 %

3/8” 95.2 97.2 97.0 ± 5 %

# 4 75.4 77.6 77.8 ± 5 %

# 8 43.8 46.4 45.2 ± 5 %

# 16 30.0 34.1 33.5 ± 3 %

# 30 20.7 22.5 22.0 ± 3 %

# 50 16.5 18.9 17.4 ± 3 %

# 100 12.0 14.0 13.7 ± 3 %

# 200 6.5 7.2 7.0 ± 0.5 %

Sieve BlankBurn #

1Burn #

2Avg. Burn


1/2” 100.0 100.0 100.0 100.0 ± 5 %

3/8” 95.2 97.2 97.0 97.1 ± 5 %

# 4 75.4 77.6 77.8 77.7 ± 5 %

# 8 43.8 46.4 45.2 45.8 ± 5 %

# 16 30.0 34.1 33.5 33.8 ± 3 %

# 30 20.7 22.5 22.0 22.3 ± 3 %

# 50 16.5 18.9 17.4 18.2 ± 3 %

# 100 12.0 14.0 13.7 13.9 ± 3 %

# 200 6.5 7.2 7.0 7.1 ± 0.5 %

Sieve BlankBurn #

1Burn #

2Avg. Burn


1/2” 100.0 100.0 100.0 100.0 0.0 ± 5 %

3/8” 95.2 97.2 97.0 97.1 -1.9 ± 5 %

# 4 75.4 77.6 77.8 77.7 -2.3 ± 5 %

# 8 43.8 46.4 45.2 45.8 -2.0 ± 5 %

# 16 30.0 34.1 33.5 33.8 -3.8 ± 3 %

# 30 20.7 22.5 22.0 22.3 -1.8 ± 3 %

# 50 16.5 18.9 17.4 18.2 -1.7 ± 3 %

# 100 12.0 14.0 13.7 13.9 -1.9 ± 3 %

# 200 6.5 7.2 7.0 7.1 -0.6 ± 0.5 %


Find the ACF and which ones need to be applied

Sieve BlankBurn #

1Burn #

2Avg. Burn


1/2” 100.0 100.0 100.0 ± 5 %

3/8” 94.3 97.2 96.5 ± 5 %

# 4 70.6 73.4 74.1 ± 5 %

# 8 41.8 43.0 44.2 ± 5 %

# 16 32.5 33.1 33.9 ± 3 %

# 30 21.0 23.6 23.0 ± 3 %

# 50 15.7 17.8 17.1 ± 3 %

# 100 11.4 12.0 12.3 ± 3 %

# 200 5.6 6.1 6.3 ± 0.5 %

2018

55


Calculate the reported % passing for the field gradation

• Add ACF

• Round

SieveSieve

AnalysisACF

Calculated % Passing

Reported % Passing

3/4” 100.0 0.0

1/2” 97.2 - 2.3

3/8” 88.3 - 3.5

# 4 56.1 - 2.4

# 8 39.5 - 4.0

# 16 29.0 - 3.6

# 30 20.4 - 2.0

# 50 13.7 - 1.0

# 100 9.1 - 0.8

# 200 5.8 - 0.6

SieveSieve

AnalysisACF


Reported % Passing

3/4” 100.0 0.0 100.0

1/2” 97.2 - 2.3 94.9

3/8” 88.3 - 3.5 84.8

# 4 56.1 - 2.4 53.7

# 8 39.5 - 4.0 35.5

# 16 29.0 - 3.6 25.4

# 30 20.4 - 2.0 18.4

# 50 13.7 - 1.0 12.7

# 100 9.1 - 0.8 8.3

# 200 5.8 - 0.6 5.2

SieveSieve

AnalysisACF


Reported % Passing

3/4” 100.0 0.0 100.0 100

1/2” 97.2 - 2.3 94.9 95

3/8” 88.3 - 3.5 84.8 85

# 4 56.1 - 2.4 53.7 54

# 8 39.5 - 4.0 35.5 36

# 16 29.0 - 3.6 25.4 25

# 30 20.4 - 2.0 18.4 18

# 50 13.7 - 1.0 12.7 13

# 100 9.1 - 0.8 8.3 8

# 200 5.8 - 0.6 5.2 5.2


Calculate the reported % passing for the field gradation

SieveSieve

AnalysisACF


Reported % Passing

3/4” 100.0 0.0

1/2” 93.2 - 2.0

3/8” 84.1 - 1.8

# 4 52.5 - 2.3

# 8 43.0 - 2.0

# 16 31.6 - 2.5

# 30 22.2 - 2.7

# 50 14.7 - 1.0

# 100 11.8 - 1.2

# 200 5.2 - 0.7

2018

56

HMA APPLICATIONS

Application Rate

• Describes the weight of asphalt needed to cover an area to produce the required thickness of pavement

• Checking the application rate ensures that the proper amount of asphalt is applied to the roadway

HMA APPLICATIONS

Application Rate (lb/yd²)• Weight of Asphalt (lb)

• Area (yd²)

• Application Rate (lb/yd²),

2018

57

HMA APPLICATIONS

Find the application rate in lb/yd² for 700 tons of asphalt placed in an area 12’ wide by 4774’ long

,,

, ,, 220 lb/yd²

,

HMA APPLICATIONS

Find the application rate in lb/yd² for 1000 tons of asphalt placed from station 62 + 20 to 101 + 67 and 16’ wide

2018

58

HMA APPLICATIONS

Quantity of Asphalt (tons)

• The weight of asphalt mixture required to cover an area to a prescribed depth or application rate

• A typical assumption is that it takes approximately 110 pounds of asphalt mixture per square yard to produce a compacted pavement one inch thick

HMA APPLICATIONS

Weight of Asphalt (tons)• Area (yd²)

• Weight (tons)

• Tons of Asphalt

,

2018

59

HMA APPLICATIONS

Find the tons of asphalt needed to pave a 10’ wide, 300 ft long drive with an application rate of 220 lb/yd²

,,, 37 tons

,

HMA APPLICATIONS

Find the tons of asphalt needed to pave a 50’ x 300’ parking lot with an app. rate of 160 lb/yd²

2018

60

SAMPLING

ARDOT 404.04 : Sampling shall be performed according to AASHTO T 168 and AHTD 465

• AHTD 465 – Procedure for Sampling by Random Number

• AASHTO T 168 – Standard Practice for Sampling Bituminous Paving Mixtures

• ASTM D 979

SAMPLING

ARDOT 404.04 Note 1 : Samples shall be obtained from trucks at the plant

AHTD 465 – Section 3.3.1 Note : First sublot test of day shall not fall within the first 5 % of production

2018

61

Used for sampling loose bituminous paving mixtures (plant mix)

SAMPLING BITUMINOUSPAVING MIXTURES

AASHTO T 168 – ASTM D 979

Equipment• Square point shovel

• Suitable containers

Sampling (Truck)• 3 Increments (min.)

• Pull from different locations (drops)

• Avoid sampling the extreme top surface

SAMPLING MIXTURESAASHTO T 168 – ASTM D 979

2018

62


Avoid loss of larger aggregates from overfilling shovel

Avoid buildup of fines on shovel

Sample should look like load sampled


2018

63

Roadway

• 3 equal samples

• Sample full depth

• Exclude underlying material

• Combine samples

Cold Mix Stockpiles

• Remove top 4” of crust

• Stir area - sample

• 3 equal samples from different areas

• Combine samples


Transportation

• Avoid contamination

• Prevent loss of material

• Maintain temperature

Labeling

• Job number

• Source of sample

• Plant / Mix

• Sample location


2018

64

REDUCING SAMPLES OF HOT MIX ASPHALT (HMA) TO TESTING SIZE

AASHTO R 47

A method used to reduce samples in physical size while maintaining the same physical characteristics as the original sample

Original Coarse Fine

REDUCING SAMPLES OF HMA …AASHTO R 47

The gradation of an HMA sample affects its volumetric properties!

Pb, Gmm, % Air Voids, % VMA, % Compaction

Sieve Design Coarse Fine

3/4” 100 100 100

1/2” 92 89 95

3/8” 81 78 84

# 4 52 49 55

# 8 30 27 33

# 16 20 17 23

# 30 16 15 18

# 50 13 11 15

# 100 9 7.5 10

# 200 5.2 4.2 6.2

Pb 5.53% 4.75% 6.27%

2018

65

Maintain Temperature

• Heat Equipment at ≤ 230º F

Coat surfaces only with approved release agent

• Release agents cannot contain solvents or petroleum-based products

Methods of Reduction

• Mechanical Splitter

• Type A

• Type B

• Quartering Method

• Incremental Method


Mechanical Splitter Type A

• Collect opposite quarters


2018

66

Mechanical Splitter

Type B

• Collect one side


Quartering

• Collect opposite quarters or equal portions from opposite quarters

Straight Edge(s)

Quartering Device


90°

2018

67

Incremental Method

• Place asphalt sample on non-stick paper or plastic

• Mix sample well

• Roll material into a cylindrical loaf

• Discard end ¼ of loaf

• Cut off (collect) desired sample sizes

• Re-mix and re-roll as necessary


Discard

PREPARING AND DETERMINING THE DENSITY OF HMA SPECIMENS

BY MEANS OF THE SUPERPAVE GYRATORY COMPACTOR

AASHTO T 312

This specification covers the compaction of cylindrical specimens of hot-mix asphalt using the

Superpave Gyratory Compactor

2018

68

Equipment• Gyratory Compactor

• Mold

• Bottom

• Top

• Oven• Thermostatically

controlled to ± 3º C ( ≈ 5° F)

• Thermometer

HMA SPECIMENS BY SGCAASHTO T 312


SGC Compaction Parameters

150 mm mold (i.d.)

Ram Pressure600 ± 18 kPa

30 ± 0.5 gyrationsper minute

1.16 ± 0.02°(internal angle)

2018

69

Mold Calibration

• Yearly or 80 hours

• Verify inside dimensions

• Three-Point Internal Bore Gauge

• Calib. Master Ring

• Mold Temperature

• 64°– 82° F

• Record 3 measurements at each height

• 50 mm from wear end

• 100 mm from wear end

• 50 mm from opp. end


All measurements must be ≤ 150.2 mm for in-service molds

Gyratory Calibration

• Frequency follows manufacturer’s recommendations

• Verify

• Internal Angle

• Pressure

• Rotation Speed

• Height Measurement

Additional Checks

• Physical movement

• Repairs which affect calibration

Optional Check

• New season of mix designs


Verify calibration at least every 12 months!

2018

70

Verify settings• Angle & pressure

• Number of gyrations• Ndes

Lubricate bearing surfaces

Preheat molds and plates to compaction temp.

• Minimum of 30 minutes

• Reheat at least 5 minutes between uses


Reduce sample• 115 ± 5 mm height

(4400 g - 4800 g)

Bring HMA to compaction temperature

• Maximum of 30 min.

Assemble mold• Largest side of plate

goes toward specimen

• Paper disk


2018

71

Place HMA in mold

• One lift

• Avoid segregation

• Level surface of HMA

Check temperature

Insert paper disc

Place top plate in mold


Load mold into compactor

Compact specimen

Remove mold from compactor


2018

72

Extrude specimen from mold

• Cool tender specimens before extruding

Remove paper discs

Allow specimens to cool to room temperature

• 2 specimens


Influenced by the composition of the mixture

• Binder

• Stone

• Moisture

Influences “pay” items

• % Air Voids

• % VMA

• % Compaction

THEORETICAL MAXIMUM SPECIFIC GRAVITY AND DENSITY

OF HMA PAVING MIXTURESAASHTO T 209

2018

73

Oven dry sample to constant mass at

• 221 ± 9º F

• Constant mass is defined as when the mass repeats within 0.1%

Cool to room temperature

Separate the sample

• No fine clusters > ¼ inch in size

• Prevent trapped air between the particles

MAXIMUM SPECIFIC GRAVITY AASHTO T 209

Weigh empty flask

• Tare out flask

Place sample into the flask

Weigh flask with sample

• Determine net mass of HMA

• Record net mass as dry mass in air (A)


2018

74


Add water to completely cover sample (77 ± 0.9º F)

Optional : Add diluted Aerosol OT wetting agent

Remove trapped air by applying vacuum

• 3.7 ± 0.3 kPa

• 27.5 ± 2.5 mm Hg

• 15 ± 2 minutes

Agitate the container at least every 2 minutes


2018

75

Release vacuum slowly• Do not exceed 8 kPa/s

or 60 mm Hg /s

Prepare water bath• Fill to overflowing

• Allow water level to stabilize

• Tare out suspension apparatus


Submerge specimen in water bath

• 77 ± 2º F

• Suspend 10 ± 1 min

• Record total submerged mass

Remove pycnometer from water bath

MAXIMUM SPECIFIC GRAVITYAASHTO T 209

2018

76

Empty pycnometer and refill water bathwater

• Allow to stabilize

Suspend empty pycnometer in water

• Allow to stabilize

Record submerged mass of empty pycnometer

MAXIMUM SPECIFIC GRAVITYAASHTO T 209


A = Mass of specimen in air

C = Mass of specimen in waterC = (wt pyc + sample) sub – (wt pyc) sub

Report to nearest 0.001

2018

77

BULK SPECIFIC GRAVITY OF COMPACTED HMA SPECIMENS

AASHTO T 166

Test method is only applicable for samples that absorb 2% or less water by volume

• If > 2 % absorption, rerun specimen

• AASHTO T 275 – Paraffin Coating

• AASHTO T 331 – Vacuum Sealing

Specimens may be laboratory compacted or cored samples from pavements

AASHTO T 275

• Paraffin Coating

AASHTO T 331

• Vacuum Sealing

BULK SPECIFIC GRAVITY AASHTO T 166

2018

78

Method A

• Dry specimen to a constant mass

• 125 ± 5º F (< 0.05 %)

• Vacuum (≥ 2 cycles)

• Cool to 77 ± 9º F

• Record Dry Mass (A)


• Prepare water bath

• Fill and allow to stabilize

• Tare out suspension apparatus

• Immerse in water at 77 ± 1.8 ºF

• Leave submerged for 4 ± 1 minute

• Record submerged mass (C)


2018

79


• Remove from water

• Quickly blot specimen dry with a damp towel (15 sec)

• Weigh and record SSD weight (B)

Any water that seeps from the specimen during the weighing is considered part of the specimen

Method C

• Obtain Submerged Mass (C)

• Obtain SSD Mass (B)

• Obtain Dry Mass (A) at the end of testing by drying specimens at 230 ± 9º F

• This method destroys the specimen but allows cores to be tested the same day


2018

80


%

A = Mass of specimen in air

B = Mass of SSD specimen

C = Mass of submerged specimen

Report Gmb to 0.001 Report % Abs to 0.01 %

Determines the moisture content of HMA by oven drying

Equipment• Balance (0.1 g)

• Oven

• Thermometer

MOISTURE CONTENT OF ASPHALT MIXTURES BY OVEN METHOD

AASHTO T 329

2018

81

MOISTURE CONTENT …AASHTO T 329

Obtain representative sample of asphalt mixture

Record tare weight of empty pan

• Include weight of liners

Place asphalt mixture into pan

• Measure temperature of asphalt mixture and record

Record mass of (moist sample + pan)


Place pan in oven and dry for 90 ± 5 minutes• Mixing Range (if specified)

• 325 ± 25 °F (if not specified)

Check weight of (sample + pan) and then at 30 ±5 minute intervals until at constant mass

• ≤ 0.05 % Change

Cool to ≈ temperature recorded

Record mass of (dry sample + pan)

% % Mp – previousmeasurementMn – newestmeasurement

2018

82


Moisture Content (% MC)

• Mi – Initial mass of asphalt mixture (wet)

• Mf – Final mass of asphalt mixture (dry)

% %

Subtract tare weight of pan to get mixture weights!

Report moisture content to the nearest 0.01 %


Determine the moisture content of the mixture

Tare Weight 244.0Wet Wt + Tare 1505.6Dry Wt + Tare 1505.1

1505.6 244.0 1261.6 1505.1 244.0 1261.1

0.04 %

% %

%. .

. %

..

% . %

2018

83


Determine the moisture content of the mixture

Tare Weight 356.8Wet Wt + Tare 1808.7Dry Wt + Tare 1798.1

DETERMINATION OF ASPHALT CONTENT OF ASPHALT MIXTURES

BY THE NUCLEAR METHODAHTD 449

Perform background count

• Time ≥ 8 minutes

• Daily log required

• Gauge moved or surroundings have changed

• ± 1 % of last background

2018

84

ASPHALT CONTENT BY AC GAUGE AHTD 449

Activate appropriate calibration

• If an interruption of mix production of more than 90 days has occurred, verify the mix calibration before use

• Prepare sample at design asphalt content

• Record date, mix design number and results

Set test time in gauge for field testing

• 4, 8 or 16 minutes


Place asphalt mixture into sample pan

• 2 lifts (work corners)

• Match calibration weight

• ± 5 g of net weight

• Compact with board until level with top rim

• Adjust weight as needed

2018

85


Measure temperature• ≈ ± 10 ºF of calib. temp.

Place sample in gauge• Close door

Start test (▼ START)• Move away ≈ 3 feet

• Record count & binder content

• Average multiple tests Record binder content to the nearest 0.01%


Determine moisture content of sample using AASHTO T 329 to the nearest 0.01%

• Subtract reported moisture content from gauge reading

• Round value to the nearest 0.1%

Report binder content to the nearest 0.1% !

2018

86

ASPHALT CONTENT BY AC GAUGEAHTD 449

Determine the reported binder content

Gauge Reading 6.20 %

Moisture Content 0.07 %

. % . % . % . %

% . %

This method determines the binder content of an asphalt mixture by physically burning the binder off the aggregate, then measuring the weight loss and converting it to a Pb

DETERMINING THE ASPHALT BINDER CONTENT OF HMA BY THE

IGNITION METHODAASHTO T 308

2018

87

IGNITION OVEN – FIELD TESTINGAASHTO T 308

To enter data : Press item desired, enter data, and press <enter> quickly. Verify data entered by pressing item again (should display correct value in window)

NCATAsphalt Content Tester

IO

Power

Printer

7 8 9

4

1

5

2

0

6

3

Weight

Temp

Calib.Factor

Enter

Thermolyne

0.0 g

Start/StopTimer

538 0.00 0:00

Percent Loss Elapsed TimeChamber Temp °C

Chamber Setpoint Sample Weight (g) Start Time

Calib. Factor


Preheat ignition oven to calibration temperature

• Input chamber temperature

• 538 °C or 482 °C

Input appropriate calibration factor

2018

88


Weigh empty basket assembly

Place ½ of the sample into the bottom basket and remaining portion into the top basket

• Keep sample away from basket edges

Weigh and record total weight of basket assembly

Calculate net weight of asphalt mixture

• Input this (net) weight into ignition oven

“Zero” Scales


2018

89

Place basket in oven

• Maintain clearance

Close and lock door

• Verify the total mass

• Scale reading must be within ± 5 g of recorded total weight

Start ignition


After Burn

• Record binder content from the printed ticket (0.01 %)

• Subtract moisture content

• Report % Binder to nearest 0.1 %

Cool sample

Elapsed Time : 57:21

Sample Weight : 1838g

Weight Loss : 116.3g

Percent Loss : 6.32 %

Temp Comp : 0.16 %

Calib. Factor : 0.33 %

Calib. Asphalt Ctnt 5.83 %

Filter Set Pt : 850°C

Chamber Set Pt : 538°C


2018

90

ARDOT GRADATION

Determined from the aggregate blend once the binder has been removed

• AHTD 460

• Solvent Wash

• AASHTO T 30

• Ignition Oven

Record total weight of aggregate

• Baskets & catch pan

Wash over # 200 sieve using a wetting agent

• Use #8, #10, or #16 cover sieve

Dry to a constant mass

Sieve sample

Calculate % Passing• Apply aggregate

correction factor

Report• All sieves except # 200

to nearest whole number

• Report # 200 sieve to nearest 0.1 %

SIEVE ANALYSIS ‐ IGNITION OVENAASHTO T 308 / T 30

2018

91

SOLVENT WASHING AND SIEVE ANALYSIS OF ASPHALT CONCRETE

AHTD 460

Uses a biodegradable solvent to wash the asphalt coating off the aggregate

• Determine binder content

• AHTD 449

• Reduce sample in size

• Record weight of mix

• Cool to ≈ 200°F

NMAS

Minimum Field

Sample Wt. (lbs)

Minimum Test

Sample Wt. (g)

½” 12 lbs 1500 g

¾” 16 lbs 2000 g

1” 20 lbs 3000 g

1 ½” 25 lbs 4000 g

2 ½” 25 lbs 4000 g

• Cover with solvent and allow to soak

• Wash over # 200 sieve

• Use # 8 cover sieve

• Repeat washing until solvent remains clean

• Wash with water / liquid detergent to remove residue

• Return aggregate retained on sieves to sample container

• Dry to constant mass

• Sieve sample

• Record weight retained on each sieve

• Calculate % Passing

SOLVENT WASH …AHTD 460

2018

92


%

Given an asphalt sample weighing 1853.4 g and a Pb of 6.2%, find the total weight of the aggregate to be used in calculating a sieve analysis.

1738.5 g .

. %%

. . .

% . % . %


Given an asphalt sample weighing 3384.2 g and a Pb of 5.3%, find the total weight of the aggregate to be used in calculating a sieve analysis.

2018

93

Compaction

External forces are used to reposition aggregate particles into a more closely spaced arrangement thereby increasing the density

% COMPACTION

% COMPACTION

4 % AV8 % AV12 % AV 0 % AV

DENSITY & % COMPACTION

% A

IR V

OID

S

2018

94

ROLLING PATTERNS

Establishes the number and type of roller passes required to achieve the specified density

• Take 15 sec WD reading with gauge after every roller pass until WD reading decreases

• Take all readings at exact same location

• Rolling Pattern

• Type of roller

• # Vibratory Passes

• # Static Passes

Rolling patterns are required under ARDOT 410.08

Used for the removal of compacted bituminous mixtures from a pavement

• Cores

SAMPLING COMPACTED BITUMINOUS MIXTURES FOR

LABORATORY TESTING…ASTM D 5361

2018

95

Equipment• Diamond-edged core drill

bit, diamond-edged or abrasive saw blade

• Cooling water, dry ice, or liquid nitrogen

• Lifting device, core debonder (optional)

• Hammer and chisel or wet saw

SAMPLING (CORES)ASTM D 5361

Core Debonder

Lifting Device

ARDOT Specifications

• ARDOT - 1 / Lot

• Contractor - 1 / Sublot


AHTD 461 Section 4.2 : Do not sample within 1.5 of the asphalt mats’ edge

Paint may affect non-nuclear density

gauge readings and may also harm the

core’s surface!

2018

96

Cores

• Diameter

• 4” minimum

• If results are erratic due to size, take larger samples

• Thickness

• Full depth of lift

ARDOT Requirements

• Thickness

• 3 x NMAS minimum required for bond breakers and levelling courses



Transportation• Avoid damage to core during removal

• Look for stress fractures

• Avoid damaging core during transport• Transport on smooth board (top side down)

• Secure cores and protect against extreme temperatures

• Do not subject cores to temperatures > 125º F• AASHTO T 166

2018

97

Separation• Done at the point of

bonding• Hammer & Chisel

• Wet Saw

• Remove tack coats and bound gravel / dirt before testing



2018

98


% %

AASHTO T 166

IN PLACE DENSITY & PERCENT COMPACTION OF ACHM USING A

NUCLEAR GAUGEAHTD 461

2018

99

Keypad

TROXLER 3430

ON YES

OFF NO

START ENTER

DEPTHTIME

SPECIALSTDMAPR

(READY) 1 minDepth : BS

Run Standard Count

• Place gauge on block

• Rod in “Safe” position

• Press <Standard>

• Move away ≈ 3 ft

Standard Count (Daily)• Used to determine the

proper functioning of gauge

• Adjusts for source decay and background radiation

Block Site Selection• Asphalt surface course

• ≥ 10’ from large objects

• ≥ 60’ from any other radioactive sources

IN‐PLACE DENSITY…NUCLEAR GAUGEAHTD 461

Metal Butt Plate

Standard Block

Safe Position

2018

100

STANDARD CHECKRATIO METHOD

Average last 4 countsDS MS

May 5th 2251 650

May 6th 2260 642

May 7th 2258 645

May 8th 2262 648

Average 2258 646

Take new countNew Counts 2234 638

Determine Ratios• Density (± 1 %)

Ratio Range = 0.99 – 1.01

• 2234 / 2258 = 0.9893

• 2258 / 2234 = 1.0107

• Moisture (± 2 %)Ratio Range = 0.98 – 1.02

• 638 / 646 = 0.9876

• 646 / 638 = 1.0125

Determine Pass/Fail

P

F

STANDARD CHECKRANGE METHOD

Average last 4 countsDS MS

May 5th 2251 650

May 6th 2260 642

May 7th 2258 645

May 8th 2262 648

Average 2258 646

Take new countNew Counts 2234 638

Compute ranges

• Density (± 1%)

• 2258 x 0.01 = ± 22

• Moisture (± 2%)

• 646 x 0.02 = ± 12

Determine Pass/Fail

• Fails – both must pass

P

F

2258 – 2234 = 24

646 – 638 = 8

2018

101

STANDARD CHECK

DS MS

May 10th 2273 589

May 12th 2260 550

May 13th 2265 565

May 15th 2262 556

New Counts 2246 573

Determine if the new density and moisture standard counts pass or fail

STANDARD CHECK

Failing Standard Count• Re-run standard count

Establish a new average• Run 4 new standard counts

• Run new standard count and compare to new average

• Pass – Proceed to testing

• Fail – Repair gauge

Gauge must pass standard count before use in the field

2018

102


Job Correction Factor (JCF)

• Eliminates gauge errors

• Surface voids

• Base irregularities

• Mix design and job location specific

• Must be determined on each project site

• JCF is applied to acceptance test results prior to calculating % compaction for each test location

Test Strip • (5) random locations

Each Location (CCF)• (4) gauge readings

• Cut (1) core


Core Correction Factor (CCF)

Dir

ecti

on

of

Pav

ing

Take readings within 1 foot

of core

2018

103

Determine each core’s bulk specific gravity (Gmb)

Convert each Gmb to a Core Density


. ³

Determine CCF

• Average (4) gauge WD readings

• Find core density

• Subtract average gauge WD from core density

• Keep track of sign

WD (1) 145.6 lb/ft³

WD (2) 148.3 lb/ft³

WD (3) 147.2 lb/ft³

WD (4) 146.6 lb/ft³

Average 146.9 lb/ft³

Core Gmb 2.301

Core Density 143.6 lb/ft³


. . . -3.3 pcf

2018

104

Job Corr. Factor (JCF)

• Average (5) core correction factors

Application of JCF

• If JCF < 1.0

• Do not use JCF

• Read density directly from gauge

• If JCF > 1.0

• Add JCF to all wet density readings before calculating % compaction


Core CCF

1 + 2.2

2 + 2.0

3 + 1.8

4 - 0.5

5 + 0.3

Avg + 1.2

Sum+ 5.8

5.8/51.2

JCF = + 1.2 pcf


Determine the job correction factor for the jobsite.

Gauge WDCore Gmb

143.3 141.5 142.8 140.6 2.312

140.5 139.8 138.4 140.0 2.285

141.5 142.8 140.3 140.7 2.310

139.5 137.2 140.0 138.8 2.251

138.2 139.3 140.1 140.5 2.277

2018

105


Field TestingSet Gauge Parameters

• Depth – Backscatter

• Time – 1 minute

Test Locations (3 / Sublot) • Dry and relative flat

• Fill voids of rough surfaces with dry sand if used when establishing JCF

• Level sand using scraper plate

Test at the same time interval (laydown to test) as JCF was established

Gauge Parameters

• Time – 1 minute

• Depth - Backscatter

Site Preparation

• Dry and Flat

• For Rough Surfaces

• Fill voids with dry sand

• Level sand using scraper plate

Testing• Stabilize gauge on

site

• Lower Source Rod (BS)

• Start (move back)

Record • Wet Density (WD)

• Station & Offset


2018

106

Testing

• Place gauge on asphalt mat with source rod in direction of lay-down

• Stabilize gauge

• Lower rod to BS position

• Start test

• Move away

• Safe Rod & Record Data

• WD reading

• Station & Offset

• Average all WD readings taken at the test location


Lay-down


% Compaction (Gauge)

• Add JCF to WD

• Divide by maximum density

• Multiply by 100

% 62.4

100%

Report to nearest 0.1%

2018

107


Determine the % compaction for the test location.

Gauge WD 138.8 pcf

JCF + 2.2 pcf

Gmm 2.422

%. .

. . %

..

% . %

93.3 %

% .

%


Determine the % compaction for the test location.

Gauge WD 139.3 pcf

JCF + 3.5 pcf

Gmm 2.465

2018

108

Report• Each Test Location (3)

• Station #

• Offset

• Include from left or right side of pavement

• % Compaction

• Reported Result (1)• According to AHTD 461

(Sect. 5.4 – 5.6)



AHTD 461 – Section 5.4 Spec: 92 – 96

• Report the average of all compaction tests if :

• A. At least 2 of the 3 are ≥ 92.0 and ≤ 96.0 % and any remaining result is not more than 2% above or below the specification limits

• B. All are below or above the specification limits and no result is more than 2% above or below the limits

90 92 93 94 95 96 97 9891

90 92 93 94 95 96 97 9891

2018

109


AHTD 461 – Section 5.4 Spec = 92 – 96• C. If all are outside specification limits (different

directions) and none are more than 2% out :

Add arithmetic differences between test and closest limit

Average the sum, and add or subtract from limit closest to two tests

92.0 – 90.3 = 1.7 (1.7 + 0.7 + 0.3) / 3

92.0 – 91.3 = 0.7 2.7 / 3 = 0.9

96.3 – 96.0 = 0.3 92.0 – 0.9 = 91.1 %

90 92 93 94 95 96 97 9891


AHTD 461 Spec = 92 – 96

• SEC. 5.5 – If (2) are outside specification limits (same side), and one is within the specification limits:

• Average only the (2) non-complying results

(91.2 + 91.8) / 2 = 91.5 %

90 92 93 94 95 96 97 9891

2018

110


AHTD 461 Spec = 92 – 96

• SEC. 5.6 – If (1) of the results are more than 2% outside the specification limits

• Report this (1) result for the test

89.6 %

89 91 92 93 94 95 96 9790


Sublot Compliance/Rejection

• If a density result for a sublot is 2% or more outside compliance limits:

• Two (2) additional tests performed by ARDOT

• If the sublot already contains both contractor and ARDOT tests results, then only one (1) additional test performed

• If the average of the three (3) tests is within ± 2% of specification limit, the sublot will be accepted and the average is the official result of the sublot

2018

111

ARDOT HMA SPECIFICATIONS

Standard Specifications• Mix design and quality control requirements

Supplemental Specifications• Changes to the Standard Specifications (Errata)

Job Plans• Mix design requirements and application rates

Special Provisions - Apply only to individual jobs• Submission of Hot Mix Acceptance Test Results

• Recycled Asphalt Shingles

• Warm Mix Asphalt

• PWL

ARDOT

• Lot = 3000 tons

Contractor

• Sublot = 750 tons

ARDOT HMASPECIFICATIONS

S2 S3 S4

Lot 1

S1

0 750 1500 2250 3000

2018

112


ARDOT Pay Items

• % Binder

• % Air Voids

• % VMA

• % Compaction


ARDOT specification limits are considered absolute limits!

• Observed or calculated values are not rounded for determination of compliance

• Compared directly with the limit

• Average values are rounded to same # of significant digits

• Any deviation outside limits is non-compliance

• Failing test

2018

113


Field Compliance (ARDOT Table 410 – 1)

Binder Content ± 0.3 % (Mix Design)

Air Voids 3.0 % - 5.0 %

VMA 37.5 mm 11.0 % – 13.0 %

25.0 mm 12.0 % - 14.0 %

12.5 mm 13.5 % - 16.0 %

9.5 mm 14.5 % - 17. 0 %

Gradation See ARDOT Section 404.04

Field Density 92.0 % - 96.0 % or 90.0 % - 96.0 %


Field Compliance (ARDOT Sect. 404.04)

ARDOT Gradation 1” (25.0 mm) ± 7.0 %

Tolerances 3/4” (19.0 mm) ± 7.0 %

1/2” (12.5 mm) ± 7.0 %

(Tolerances are # 4 (4.75 mm) ± 7.0 %

applied to the # 8 (2.36 mm) ± 7.0 %

job mix formula) # 16 (1.18 mm) ± 4.0 %

# 30 (0.60 mm) ± 4.0 %

# 50 (0.30 mm) ± 4.0 %

# 100 (0.15 mm) ± 4.0 %

2018

114



Determine which (if any) of the pay items will result in a pay deduction or rejection of the lot.

Test % Binder % Air Voids % VMA % Density

Sublot 1 4.2 2.5 12.5 92.2

Sublot 2 3.8 3.3 11.2 91.9

Sublot 3 4.4 3.2 12.9 91.0

Sublot 4 4.6 4.0 12.2 93.1

Lot 4.5 3.7 12.8 91.8

Average 4.30 3.34 12.32 92.00

Compliance 3.9 – 4.5 3 - 5 12.0 – 14.0 92 - 96

25.0 mm Mix Design Optimum Pb = 4.2 %

2018

115


PWL

Percent Within Limits• An alternative method of determining compliance

and calculating pay

• Used for jobs let by ARDOT under a special provision for new construction projects and jobs with full depth reconstruction

• PWL analysis is performed only on lots which contain 3 or more test results

PWL

Total Pay Factor < 80 = “Remove and Replace”

2018

116

PWL

Average

LSL USL

PWL

PWL – Percent Within Limits (Good)

% Air Voids

LSL = 3 % USL = 5 %

Sublot 1 4.0 %

Sublot 2 4.2 %

Sublot 3 3.8 %

Sublot 4 3.9 %

Lot 4.1 %

Average 4.00 %

PWLT = 100.00 PFPAV = 105.00

Non-PWL = 100 % Pay

2018

117

PWL

PWL – Percent Within Limits (Fair)

% Air Voids

LSL = 3 % USL = 5 %

Sublot 1 4.8 %

Sublot 2 5.2 %

Sublot 3 4.2 %

Sublot 4 4.6 %

Lot 4.0 %

Average 4.56 %

PWLT = 81.23 PFPAV = 95.62

Non-PWL = 100 % Pay

PWL

PWL – Percent Within Limits (Fair)

% Air Voids

LSL = 3 % USL = 5 %

Sublot 1 3.3 %

Sublot 2 5.2 %

Sublot 3 4.2 %

Sublot 4 4.6 %

Lot 4.0 %

Average 4.26 %

PWLT = 85.09 PFPAV = 97.55

Non-PWL = 100 % Pay

2018

118

PWL

PWL – Percent Within Limits (Poor)

% Air Voids

LSL = 3 % USL = 5 %

Sublot 1 2.6 %

Sublot 2 3.2 %

Sublot 3 3.1 %

Sublot 4 4.5 %

Lot 2.8 %

Average 3.24 %

PWLT = 61.33 PFPAV = 85.67

Non-PWL = 100 % Pay

HOT MIX ASPHALT TESTING TECHNICIAN - cttp MIX ASPHALT TESTING TECHNICIAN ... If an asphalt core has a specific gravity of 2.335, ... Allowable Field Tolerances 5.1 % to 5.7 % 3.0 %

Documents