·dP f.mr.st~t'::n prOJ=~ p'!:'artrr '.chnology Ycanst., FHWA·Dp·37·14 August 1980

DEMONSTRATION PROJECT NO. 37

DISCARDED TIRES IN HIGHWAY CONSTRUCTION

HILLSBOROUGH COUNTY, FLORIDA

Pr.par.d for and Dlstrlbut.d by

U.S. DEPARTMENT OF TRANSPORTATION FEDERAL HIGHWAY ADMINISTRATION REGION 15 DEMONSTRATION PROJECTS DIVISION 1000 NORTH GLEBE ROAD ARLINGTON, VIRGINIA

NOTICE

This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liabil ity for its contents or use thereof.

fLORIDA DEPARTMENT Of TRANSPORT~TION

Office of Materials and Research

P . O . Box 1029

Gainesville, Florida 32602

INITIAL REPORT

EVALUATION OF ASPHALT-RUBBER AS A STRESS ABSORBING INTERLAYER AND A BINDER

fOR SEAL COAT CONSTRUCTION (SR 60. Hillsborough County)

by

Kenneth H. Murphy Bituminous Engineer

~d

Charles F. Potts Principal Investiga1:or

State Haterials and Research Engineer

Prepared Under Contract with the U. S . Depart~ent of Transporation. Federal Highway Administration

Region 15 Arlington, Virginia

Contract No. DOT-FH-15-328

June, 1980

TABLE OF CONTENTS

LIST OF METRIC EQUIVALENCIES --------------------------------------- ii

LIST OF TABLES ---------------------------------------------------- iii

LIST OF FIGURES ---------------------------------------------------- iv

ABSTRACT -- ---------- -------_____ ------------ ------ ------ ------ ----- v

INTRODUCTION ---- - - - ----- ---- - ------------- ------------- - --- -- - 1

PURPOSE AND SCOPE -------------------------------- ------------- 1

PROJECT DESCRIPTION -- --------------------------------------- 2

PRELIMINARY INVESTIGATION

Description of Existing Roadway ------_______________________ 4 Traffic Volume ------___________________________________ ___ _ 4

Present Serviceability Index Values (PSI SV ) ------------ ----- 4

Rut Dept:h Measurements ---- - -- ----- ------ - ------------------ 5 Benkelman Beam Deflections ------------------- - --------- - - - - - 5 Cracking --- ----------- --------------- ---- - - --------------- 5

CONSTRUCTION PROCEDURE ---------------------- ---- - - ------------ 6

POST-CONSTRUCTION PERFORMANCE ------- --------- - ---------------- 9

Friction Numbers ------ --- - -------------------------- ------ 9 Present Serviceability Index Values - - ------ - ---------------- 9 Rut Depth Measurements ---------------- - ----- ------ ---------- 10 BenkelJnan Beam Deflections ----------------- --------- - - ----- 10

ENVIRONMENTAL CONSIDERATIONS --------- - ---------------------- 10

COST ANALYSIS ------------------------------------------------- 10

SIX-MONTH PAVEMENT PERFORMANCE EVALUATION --------------------- 11

SUMMARY ---------------------- - -------------- - -- - --------- - ---- 14

i

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LIST OF TABLE S

Table

1 Summary of Field Evaluation - - - ---------------------------- 15-16

2 Aspha1t - Rubber lnterlayer (Spread Rates) - ---------------------------- - ------------- 17

3 Asphalt-Rubber Interlayer (GradaT:ion Analyses and Los Angeles Abrasion) --- ---------- 17

Gradation of Crumb Rubber and Penetration of Asphalt-Rubber Mixture ------------------ ------------- - ---- 18

5 Mix Des ign - Type S- l MixT:ure - --- ----------------------- 19

6 Mix Design Data - FC-2 HixT:ure - ------------------------ -- 20

7 AsphalT:-Rubber Seal CoaT: (Spread Rates) --- - -------------------------------------- 20

8 Asphalt-Rubber Seal COaT:

<,GradaT:ion Analyses and Los Angeles Abrasion) ------------ - 21

9 Type II Modified Surface TreatmenT: (Spread Rat es) -------------------------------------------- 21

10 Type II Modified Surface TreaT:1l1ent (Gradation Analyses and Los Angeles Abrasion Values) ------ 22

iii

•

LIST or FIGURES

Figure

1 Asphalt-Rubber Test Sections ------------------------------ 23

2 Typical Cracks in Existing Pavement ----------------------- 24

3 Crumb Rubber --____________________________________________ 25

Conveying Crumb Rubber and Mixing with Asphalt Cement .(AC- 20) in the Distributor Truck __________________________ 25

5 Applying Asphalt-Rubber Membrane ------- ------------------- 26

6 Spreading Chips on Asphalt-Rubber M.embrane --- - ------------ 26

7 Rolling Asphalt-Rubber Seal Coat ---------------- - --- ----- 27

8 Surface Texture of Asphalt-Rubber Seal Coat --------------- 27

9 Pre-coated Slag Chips for Seal Coat ----------------------- 28

10 Surface Texture - Type II Modified Surface Treatment ------ 28

iv

ABSTRACT

In the latter part of 1978, t en experimental sections were const ructed in

Florida to evaluate the field performance of asphalt-rubber material when used

as a stress absorbing membrane and as a binder in seal coat construction.

The field testing includes condition surveys , post construction analyses

and a pavement performance evaluation of the pavement after six mOn'!:hs .

The initial results indicate an acceptable pavement can be produced with

the asphalt-rubber materials when the proper design and construction procedures

are used . Further field evaluations will be necessary in order to draw definite

conclusions with regard to long-term pavement performance and cost effectiveness

of the asphalt-rubber material.

v

EVALUATION Of ASPHALT-RUBBER AS A STRESS ABSORBING INTERLAYER AND A BINDER

fOR SEAL COAT CONSTRUCTION

(SR 60, Hillsborough County)

INTRODUCTION

One of the most common types of pavement distress is ~remature

cracking of asphalt pavements . Such cracking is associated with ~epeti-

tive loading on pavements with an elastic or resilient substructure.

A variety of solutions have been proposed to eliminate or at least

retard the reflection of these existing cracks into new s tructural over-

lays. In moSt cases , these approaches have not proven to be cost

effective .

During the early 1960 ' s . a process was developed using a composi-

tion of 25 percent ground reclaimed tire rubber reacted with 75 percent

asphalt cement to form a material with good visco-elastic propert ies .

Th is asphalt-rubber material is used to form a stress absorbing inter-

layer when spread over the cracked surface prior to overlay or as a seal

coat to provide a wearing surface on existing pavement structures.

PURPOSE AND SCOPE

The purpose of this project is to evaluate the field performance of

the asphalt-rubber material when used as a . stress absorbing membrane and

as a binder in seal coat construction.

The ability of the material to control reflective cracking , and its

cost effectiveness as compared to conventional methods of pavement rehabi-

litation , will be evaluated based on the field performance of the indi-

vidual test sections .

PROJECT DESCRIPTION

This project is located in the eastbound lane of SR 60 , east of

Brandon , in Hillsborough County .

Ten experimental sections approximately 1,000 feet in length were

constructed to evaluate the asphalt-rubber systems . Six of these sec-

tions incorporated the asphalt-rubber concept; two as seal coat s and

four as interlayers . The remaining four sections were standard type

construction employed by the florida Depart ment of Transportation and

are considered as control sections. All leveling , intermediate, and

surface courses were standard f l orida Department of Transportation

mixes .

A schematic diagram of the test sections is shown in figure 1 . The

following is a brief description of the individual test sections:

Section 1

This sect ion is located between Stations 0+00 (SR 640 intersection) and 10+00. Paving consists of 75 psy Type S-1 leveling , l~ inches of Type S- l intermedi~te course , an asphalt-rubber inter­layer utilizing approximately 0.6 gpsy asphalt-rubber in conjunc­tion with AASHTO Grade No. 7 cover material, and an open graded friction course (fC-2).

Section 2

This section is located between Stations 10+00 and 20+00 . Over­lays consist of 75 psy Type S-l leveling , ~ inches of Type S-l intermediate course , an asphalt-rubber interlayer utilizing approximately 0.6 gpsy asphalt-rubber in conjunction with AASHTO Grade No . 7 cover material, and an open graded fric­tion course (rC-2) .

Section 3

This section extends from Station 20+00 to 30+00. It consists of an asphalt-rubber interlayer utilizing approximately 0.6 gpsy asphalt- rubber in conjunction with AASHTO Grade No. 7 cover material applied directly on the existing pavement surface , a 75 psy Type 5-1 leveling course, 2l:i inches of Type S-l inter­mediate course, and an open graded friction course (FC-2).

2

Section 4

This section is located between Stations 30+0 0 and 40+00. It consists of an asphalt-rubber interlayer utilizing approximately 0 . 5 gpsy asphalt-rubber in conjunction with AASHTO Grade No.7 cover material applied directly on the existing pavement surface. a 75 psy Type S-l leveling course. l~ inches of Type S-l inter­mediate course. and an open graded friction course (rC-2).

Section 5

This is a control section without the asphalt-rubber interlayer for comparison to Sections 2 and 3. It is located between Stations 40+00 and 50+00. Paving consists of 75 psy Type S- l leveling, ~ inches of Type S-l intermediate layer . and an open graded frict i on course (rC-2).

Section 5

This section is located between Stations 50+00 and 60+00. Paving consists of 75 psy Type S- l leveling , followed by an asphalt­rubber seal coat of approximately 0.6 gpsy covered with an appli­cation of No . 6 slag (AASHTO M-43 modified to provide 100 percent of the material to pass the 3/4-inch sieve) .

Section 7

This is a control section for comparison with Section 6. It is located between Stations 60+00 and 70+00. Paving consists of 75 psy Type S-l leveling followed by a Type II modified surface treatment.

Section 8

This is a control section without the asphalt-rubber interlayer for comparison to Sections 1 and 4. It is located between Sta­t i ons 70+00 and 80+00. Paving consists of 75 psy Type S-l level­ing. l~ inches of Type S-1 intermediate course . and an open graded friction course (rC-2).

Section 9

This is a control section for comparison with Section 10 . It consists of a Type II modified surface treatment placed directly on the existing surf ace and is located between Stations 362+00 and 372 +0 0.

Section 10

This section is located between Stations 372+00 and 382+00. Paving consi sts of an asphalt-rubber seal coat applied at a rate of approxi­mately 0.6 gpsy directly over the existing surface . The cover material

3

consisted of a single application of No. 6 slag (AASHTO M-43 modi­fied t o allow 100 percent of the material to pass the 3/4-inch sieve) .

PRELIMINARY INVESTIGATION

Description of Existing Roadway

The existing roadway was constructed in 1961 in compliance with the

1959 Edition of the Standard Specifications for Road and Bridge Construc-

tion. The original roadway structure consisted of an a-inch limerock

base , a 2-inch binder course , and a I-inch Type I asphalt concrete sur-

face course. A slurry seal followed by a Type II modified surface

treatment was applied in 1972.

A preliminary pavement performance analysis was conducted in the

eastbound traffic lane prior to construction of the test sections .

Traffic Volume

The roadway serves as a feeder route for heavily loaded truck traf-

fie associated with the citrus and phosphate industries in the area.

~ffic records (1977) show the average daily traffic (ADT) to be

17 , 500, with 17 . 4 percent trucks.

Present Serviceability Index Values (PSI SV )

The preliminary PS1SV values (based on slope variance only) were

determined using the Mays Ride Meter. Results of these tests varied

f rom a low of 1 .16 in Section 2 to a high of 3 . 13 in Section 9 . The

preliminary values for all sections are shown in Table 1. The sections

containing an asphalt-rubber interlayer or seal coat are grouped with

the respective control section so that direct comparisons of performance

can be made .

4

The tests were performed in accordance with Florida Method of Test

Designation FM 5-509 .

Rut Depth Measurements

Rut depth measurements were made at 100-foot intervals in Sections 1

through 4, 9 and 10. Preliminary measurements in the remaining sections

were excluded because leveling operations had started at the 'time of the

evaluation .

The measurements taken varied from 0 . 37 to 0.58 inch in the various

sections as shown in Table 1 .

There was only slight rutting in Sections 9 and 10 , allowing the

surface treatment and seal coat to be applied without a leveling course .

Benkelman Beam Deflections

Benkelman Beam deflection measurements were made at 100-foot intervals

throughout each test section. The measurements were obtained from both

the inside and outside wheelpaths of the eastbound traffic lane .

The values varied from 0.007 to 0.020 inch throughout the project.

The average deflect ion measurements f or each test section are summarized

in .Table 1 .

The results of these tests as compared to results from previously

tested roadways indicate the existing pavement had an adequate structural

strength even through severe cracks were present .

Cracking

Visual observations indicated from 7 to 160 square feet per 1,000

square feet of Class II and Class III cracking in Sections I through 4

5

and Sec~ions 9 and 10. Leveling work had started on the remaining sec­

tions before observations could be made .

Results of the crack survey are presented in Table 1 , and Figure 2

shows typical cracks in the existing pavement .

CONSTRUCTION PROCEDURE

The equipment used to place the asphalt -rubber is the same as for

standard seal coat operations except for the asphalt distributor. The

standard equipment includes a chip spreader and sufficient pneumatic

tired rollers to cover the entire mat on the initial pass.

The distributor ~ruck used is a more comple x piece of equipment

than normally used in the application of asphalt cements or emulsions

for seal coat work . The truck was equipped with a sophisticated mixing

system which includes a screw agi~ator that extends the entire length

of the inside of the mixing tank. Oversized orifices are used on the

spray bar to prevent clogging of t he asphalt-rubber mixture. In addi­

tion , ~he tank has a burner system to externally heat the asphalt-rubber

mixture to the elevated temperatures necessary for the spray application .

Hixing of the rubber with the asphalt is accomplished at the job

site . The ground rubber is delivered to the site in 50-pound bags and

placed in the distributor by a conveyor belt (Figures 3 and 4). The

'asphalt cement is heated t o a temperature of 350 to 4000r prior to add­

ing the rubber. After the rubber is added and mixed for a minimum of

five minutes, the mix is diluted on a volume basis with from 5. 5 to 7 . 5

percent kerosene . The percentage of kerosene is adjusted as required

to provide a suitabl~ viscosity of the material for uniform application .

6

The asphalt-rubber int er layers wer e applied in Sections 1 through 4

at a rate of approximately 0 . 6 gpsy (Figure 5) . A single application of

No . 7 limestone aggregate , preheated to a temper ature of approximat ely

290oF, was applied directly behind the asphalt-rubber distributor (Figure

6) . If the asphalt- rubber mixture cool s before the chips are spread ,

the elasticity of the material prevents the chips from seating properly .

Three pneumatic-tired rollers were used (Figure 7). Two followed

directly behind the chip spr eader ; while the third . moving at a faster

pace , rolled the entire length of the completed section.

A tack coat was applied directly on the old surface in Sections 3

and 4 prior to sprayi ng the asphalt-rubber membrane . Since the old pave­

ment surface was clean. it was determined that the tack coat would not be

required on the rema i ning sections .

Spread rates for the tack coat. asphalt-rubber membrane , and lime­

stone cover material placed i n the i nterlayer sections are list ed in

Table 2.

Samples of the No . 7 limestone used in Sect ions I through 4 were

taken for gradation and Los Angeles Abrasion tests . Result s of t hese

tests are shown in Table 3.

The gradation of the ground rubber and the average penetration value

of the asphalt-rubber mixture as determined from field samples are shown

in Table 4 .

The asphalt-rubber interlayers in Sections 1 and 2 wer e covered

with the friction course (FC-2). and the interlayers in Sections 3 and 4

wi th t he Type S-l leveling course pr ior to opening the sections to

traffic.

7

Placement and compaction of the TYPe S-l leveling course , Type S~l

intermediate course , and Type FC-2 friction course in the inter layer and

control sections was accooplished by conventional means , meeting standard

specification requirements .

The design blend for the Type S-l and FC-2 mixtures are given in

Tables 5 and S, respectively .

In Section 6, the asphalt-rubber seal coat was applied following a

75 psy Type S-l leveling course. The No . S slag chips used in this

section were not pre-heated or pre-coated (Figure 8) .

In Section 10, the asphalt-rubber seal coat was applied directly on

the old pavement surface . The No . S slag chips were preheated to a tem­

perature of 2900 F and pre-coated with 0 . 5 percent asphalt cement (AC-20)

(Figure 9) .

The procedure and equipment used for placing both the seal coat

sections was the same as used in the interlayer sections .

After rolling was completed and the surface cooled to a tempera­

ture where the aggregate particles were not easily dislodged, traffic

was allowed on the pavement at a reduced rate of speed .

The spread rates for the asphalt-rubber and slag chips for Sections

Sand 10 are summarized in Table 7 .

Gradation analyses and Los Angeles Abrasion test values for the slag

used in these sections are included i n Table 8 .

The Type II modified surface treatment in Section 7 was constructed

over a 75 psy Type S-l leveling course to serve as a control section for

the seal coat in Sect ion S.

The surface treatment in Section 9 was constructed directly over

the existing pavement to serve as a control section f or comparison with

the seal coat in Section 10 (Figure 10).

a

The surface treatment in both sections was constructed in accordance

with standard Florida Depart~ent of Transportation specifications.

The spread rates for the emulsion (AE-90), No.6 slag (first course),

and No . 89 slag (second course) used in the surface treatment are sum­

marized in Table 9 .

The gradation analyses and Los Angeles Abrasion test values for the

No. 6 and No . 89 slag are included in Table 10.

POST- CONSTRUCTION PERFORMANCE

A pavement performance evaluation was conducted on the completed

test sections on April 2 , 1979.

Friction Numbers

Friction measurements were made at 40 mph (FN40 ) i n accordance with

ASTM E 274-77 . Results of the friction measurements indicate that good

skid resistance was obtained in all sections following construction.

Results of these tests are recorded in Table 1.

Present Serviceability Index Values

PSISV values were determined using the Mays Ride Met er . Results

of the tests indicate the rideability to be good in Sections 2 , 3, 4 ,

and B, while the seal coat and surface treatment sections showed very

little improvement (Table 1) . The low value in Section 1 .. ·as caused by

a fuel transport which over turned a t the west end of the section shortly

after completion of construction. The fuel spillage and subsequent

surface maintenance resulted in surface distortion .

9

Rut Depth Measurements

The only sections with measurable ruts after construction are the

surface treatment (Section 9) and seal coat (Section 10) sections, which

were constructed without a leveling course. Results of these measurements

are listed in Table 1 .

Benkelman Beam Deflections

Benkelman Beam deflection measurements were made at lOa-foot inter­

vals in both the inside and outside wheelpaths throughout the test sections.

As expected . there was a reduction in the deflection measurements in all

sections except Sections9 and 10 . The surface treatment and seal coat

placed in these sections without a leveling course were not considered to

have any structural strength.

The deflection measurements for each test section are shown in com­

parison with the measurements on the existing pavement in Table 1.

ENVIRONMENTAL CONSIDERATIONS

The use of discarded tires in pavements would provide a definite

ecological advantage . Environmental regulations no longer allow open

burning to dispose of the used tire casing . It is estimated that there

are over two hundred million tires discarded each year. This would pro­

vide enough rubber to construct approximately 47.400 lane miles of seal

coat or stress absorbing interlayer at the rate of 0.6 gpsy.

COST ANALYSIS

If the asphalt-rubber seal coat or stress absorbing interlayer is

to be cost effective, it can only be used where it will function properly

at a cost equal to or lower than other adequate solutions.

10

The cost of ~he seal coat on this project was approximately IWO

and one-half times ~he cost of a standard surface treatrr.ent. The cost

of the interlayer was equivalent to 3.75 inches of Type S-l pavement .

Direct cost comparisons are difficult to evalua~e because of many

variables involved. The cost of the asphalt-rubber systems can be from

one and one-half to four times higher than a standard seal coat depending

on ~he size of the project, location, etc.

In order to de~ermine accura~ely the cos~-benefit figures on this

project , the period of time that the pavement life is extended in ~he

asphalt-rubber sections will have to be obtained from the performance

analysis of each of the test sections.

SIX-MONTH PAVEMENT PERFORMANCE EVALUATION

A pavemen~ performance evalua~ion was conducted after the test

sect ions had been exposed ~o traffic for approximately six mon~hs . The

condition of each section was determined to be as follows:

Sec~ion 1

Rut depth measurements of 0 , 61 inch were found in this section

along wi~h severe flushing of asphal~ in the wheelpaths . This uns~able

condition is apparently the result of placing the asphalt-rubber inter­

layer directly benea~h the open graded friction course (FC-2). It is

believed that the aggregate in ~he friction course was partially embedded

into the asphalt-rubber inter layer after being exposed to heavy traffic

loads, causing the asphalt to be flushed to the surface .

The friction number (FN40 ) in this section decreased from 37 follow­

ing construction to 16 after six months .

11

Section 2

The asphalt-rubber interlayer was also placed directly beneath the

friction course in this section; however , the rutting and flushing of

asphalt was found to be not as severe as in Section 1. Flushing of the

asphalt had not progressed to a point that would effect the skid resis­

tance as evidenced by the high friction numbers (rN~o) obtained .

Section 3

The asphalt-rubber inter layer in this section was placed directly

on the old surface prior to leveling . No pavement distress was detected

during visual observat ions. and results of tests performed indicate the

section to be in good condition.

Section ~

The asphalt-rubber inter layer in thi s section was also placed directly

over the old pavement surface .

The test section was considered to be in good condition based on

visual observations and results of the routine pavement performance tests .

Section S

Section S is a control section without the addition of asphalt­

rubber for comparison with Sections 2 and 3.

Based on visual observations and routine pavement performance tests,

this section was considered to be in good condition.

Section 6

The asphalt-rubber seal coat in this section was placed over a 7S

psy Type S-l leveling course .

12

The pavement has shown some distress including flushing of the

asphalt-rubber membrane in the wheelpaths and raveling at the centerline .

The flushing is probably the result of the coarse cover material in

the seal coat being partially embedded in the underlying l eveling course .

Raveling at the centerline is believed to have been caused by

improper overlapping at the joint . Failure to pr e-heat or pre-coat the

cover material could also have contributed to the raveling problem.

The average rut depth in this section was determined to be 0 .23 inch .

Friction numbers decreased from an FN40 of 45 following construction, to

32 at the time of this evaluation .

Section 7

The Type II modified surface treatment in this section was con­

sidered to be in good condition except for slight flushing in the

wheelpaths.

The friction numbers obtained indicate that the flushing had not

progressed to a point that would adversely affect the skid resistance

(Table 1) .

Section 8

This is a control section which excludes the use of the asphalt­

rubber interlayer . This section was included for direct co~parison with

Sections 1 and 4.

Based on visual observations and results of routine pavement per­

formance tests, this section was considered t o be in good condition .

Section 9

This is a control section (Type II modified surface treatment placed

directly over old pavement surface) for comparison to Section 10.

13

Based on visual observations , this section was consider ed to be in

good condition .

Section 10

The asphalt-rubber seal coat in this section was considered to be

in good condition. It was placed directly over the old pavement surface

and the chips were pre-heated to 2900 r and pre-coated with 0 . 5 percent

asphalt cement (AC-20).

SUMMARY

The test sections have not been in service sufficient time to war-

rant a final analysis of this project; however, observations and data

collected to date appear to substantiate the following:

(1) Open graded plant mix seal coats should not be placed directly over the asphalt-rubber interlayers due to the high percentage of asphalt cement in these types of mixtures . Performance of sections constructed in this manner indicates a tendency for flushing of the fric­tion course.

(2) Performance to date tends to indicate the asphalt-rubber interlayer performs best when applied directly over the old surface rather than between freshly placed leveling courses and subsequent structural layers. When the asphalt-rubber interlayer is placed over new asphalt concrete mix, a portion of the cover material tends to be embedded in this layer when the mix is still tender which enhances flushing of the asphalt-rubber.

(3) To prevent raveling and promote adhesion, the aggregates used in the asphalt-rubber seal coat application should be pre -heated and pre-coated.

(4) When placing an asphalt - rubber seal coat , the joints at the centerline should be overlapped at least 4 inches in order to reduce the potential for raveling in these areas.

(5) A realistic cost-benefit analysis can not be obtained until some determination can be made with regard to the total service life of the various test applications .

,.

fABLE 1

SUMl'.ARr Of flELD tvAWATION

Test • Af1:er ,,. """ "'" "'NO

Section ConstMloCtion ."" ... ,-" rear • ,~.

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Rut Depth (inch)

lleflkhman Beano (inch)

CNckina: ( Sq. rt./l,OOO Sq.f't )

••• fN~O

II

Rut Deptb (incb)

C1->ac:kina (Sq . ft . /l , OOO Sq. rt.)

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, , • , "'" , "'" • "'" , "" n',

• "" "" • "'" '" , , • , , • , , ,

, .. , , "'" , .. , , "" '" ,

"" "" , "" '" , , , , , ,

1.17 2.95 2.911

0 . 020 0.013

0.015 0 . 010

0 . 009 0 . 009

'" '"

1.l6 2.98 2 . 28

0.119 0.37

0.013 0.010

0 . 010 0.007

0 . 012 0 . 010

'" "

3.52 11 .37 4. 25

0.00 0.00 0.00

0.0111 0.013

O.Olli O.O.lO

0.008 0 . 010

'" '" '" " " "

11.03 11.37 11.37

,." ,." ,." 0 . 010 0.009

0 . 006 0.007

0.010 0. 009

'" '" '" .. " "

(continued)

• Telt Sections 1 , II

• Asphalt Rub~r Interlayer Ul:!" Type S-1 & Leveling)

Control Section

Test Sect ions 2 '3 Asphalt . Rubber Interl.ayer (2l:!" Typ. S-l " Leveliupl

5·_ Control Se<:.tion

OIlP - Outside Whulp.lo.th

IVP - In.id. lIhulpuh

15

3.6~

11.01 ~. 2B

0.61 ,.'" 0.l9

O.OOB 0.008

0.011 O.OlO

,.'" 0.006

'" '" '" " ., "

3.97 3.87 11.33

O. 1111 0.29 0.16

0.006 0.006

0.006 0.006

0 . 009 0 . 006

'" '" '" " ., "

•• • PSI sv - Present Serviceability Index (Slop. V. riane. Only )

fric1:ion NUlllber .10 110 ..ph ...

TN"O -

TABU:: 1 {()Ontinu~d)

Type Ten! Tut • trlstint After Sb ,," "'" ..... 1'.<!ls......,_nt S.ction rlVe/lII!n1: Cbns1:f'Ue1:ion Kon1:M ,- ,- rears ..

PSISY , 1..9" 3.12 3.55 , 2."B 3.03 3.59

Rllt Ileptll , "" 0.00 0 . 23

(inell) , '"' 0.00 0.21

Benktlooan ""'. , ,." 0.011 0.010 0.009 (inch) '" O.OOB 0 . 009 0.007 , ,." 0.009 0.0ll. O.OOB

m 0.010 0 . 010 O.OOB

CNckiTII: , 00' "'" (Sq.rt./1,OOO SQ..Ft.) , '" 000 ...

rN .. o ,

" " , .. "' ** PSI

SY , 3.13 3.52 3.B2

" 3.0" 3.70 3.70

Rut o.p1:h , '"' 0."3 0 ..... 0 ... 2 .

(inch) " '" 0."5 0."2 0."3

Benku-n .... , '"' 0.01" 0.015 0.012

(inch) '" 0.015 0.013 0.015

" '"' 0.018 0.01" 0.012

"" 0.01" 0.013 0.013

CNckin& , , 00 00 (Sq.rt.!1 , OOO Sq.rt.l " " 00 00 ... rN .. o

, " " " " "

• .. Test Section , Asphalt-Rubber Seal , . ., PSI

SY Present Serviceability IndeK

(With Levtllin&l (Slope VlrilDCe Only) ... , Control "'" FrictionHumber It .. 0 .oh

Test Section , Control

" .upha1t-lQ)bber Seal 000. (without Le veliIll)

"'" Outside Wheelpath

'" Inside Whflllpath

16

Material

RS-2 Tack Coat (gpsy)

Asphalt-Rubber (gpsy)

TABLE 2

ASPHALT-RUBBER INTERLAYER (Spread Rates)

Section Number

1 2 3

0 0 0 . 05

0.56 0 .56 0.58

No . 7 Limestone (psy) 22 22 22

TABLE 3

4

0.06

0 .64

22

ASPHALT-RUBBER INTERLAYER (G~adation Analyses and Los Angeles Abrasion)

No. 7 Limestone

Sieve Percent: Size Passing

3/4" 100

1/2" 95

3/8" 65

No. 4 11

No. 10 4

No. 16 3

Los Angeles Abrasion ",,' ~ 38%

17

TABLE 4

GRADATION OF CR!JMB RUBBER AND PENETRATION OF ASPHALT-RUBBER MIXTURE

Crumb Rubber

Sieve Percent Size Passing

No . B 100

No . 10 99

No . 00 2. 2

Asphalt-Rubber Mixture

Penetration @ 770r (100 g . 5 sec.) = 108 1/10 rom

18

TABLE 5

HIX DESIGN DATA - TYPE S-l HIXTURE

Material - Percent passing

sieve S-lA S- lB Commercial Local Mineral Size Crushed Crushed Sand Sand Filler Job Mix Specification

Stone St one ( 10\> (23\) (2\) Formula Range (35\) (30\ )

--3/4" 100 100 1 00 100 100 100 100

1/2" 93 100 100 100 100 97 SS-lOO ~ ~

3/8" 63 100 100 100 100 86 75-93

No. 4 17 40 100 100 100 53 47-75

No . 10 1 5 98 100 100 37 31-53

No. 40 1 4 36 94 100 29 19-35

No. 80 1 3 5 31 100 11 7-21

No. 200 0 . 8 2 . 0 1.0 4.7 90 3 . 7 2-7

Asphalt Cement (AC-20) Content = 6 . 2\

Sieve Size

1/2"

3/8"

No. 4

No . 10

No. 200

Sect ion· Number

S

10

TABLE 6

MIX DESIGN DATA - FC-2 MIXTURE

Slag Local Mineral Job Mix Sand Filler Formula (96%) ( 2%) (2%)

100 100 100 100

88 100 100 89

34 100 100 37

S 100 100 10

0.3 90 90 2.2

Asphalt Cement (AC-20) Content - 6 . 0%

TABLE 7

ASPHALT-RUBBER SEAL COAT (Spread Rates)

Asphalt- No . S Pre-Heat Rubber Slag Temperature (gpsy) (psy) (oF)

0 . 63 29.0 0

0.60 30 . 6 290

20

Specification Range

100

85-100

10-40

2-10

2-'

Pre- Coat Content

(\)

0

0 . '

Section Number

7

9

TABLE 8

ASPHALT-RUBBER SEAL COAT (Grada~ion Analyses and Los Angeles Abrasion)

No.6 Slag

Sieve Size

Per<:en~

Passing

1 " 100

3/4" 94

1/2" 38

3/S" S

No . 4 3

No . 10 3

No. 16 2

Los Angeles Abrasion Loss = 41\

TABLE 9

TYPE II MODIFIED SURfACE <Spread Ra~es)

TREATMENT

AE-90 Emulsion (gpsy) No . 6 No . 89 Slag Slag

ls~ Course 2nd Course (psy) (psy)

0 . 24 0 . 23 26 " 0.24 0 . 26 25 18

21

TABLE 10

TYPE II MODIFIED SURFACE TREATMENT (Gradation Analyses and Los Angeles Abrasion Values)

Sieve Size

1 " 3/4"

1/2"

3/B"

No. 4

No. 10

No. 16

Percent Passing

No. 6 Slag No. 89 Slag (1st Course) (2nd Course)

100 100

97 100

"' 100

10 100

2 53

2 11

2 5

Los Angeles Abrasion Loss

No.6 Slag 40\

No. 89 Slag 39\

22

Sect. No.

~ w

1

FC-2 Ar.I

2

FC- 2 ' ARI

2 1/2" 5- 1

ASPHALT-RUBBER TEST SECTIONS

PROJECT NOS . 10110-)5)9 & 3540

HILLSBOROUGH COUNTY

3 4 5 6 7

FC- 2 2 1/2" S-

1 "1/2" S- l

1 1/2" S-l 75 lbs. S-l LeveUnp, 2 1 /2" ' 5- 1 AR5C I T-2 Mod.ST 7

St a , 0 No. ~

o

l\Js, s-l LcveUn

.' g + o M

o 'i' o N

ARl

ARI - Asphalt Rubber Inter1aYH

ARSC - Asphalt Rubber Seal Coat

o

~ M

o 'i' o ~

75 1bs , 5-1 Leve1in

~ ~

Fi gure 1

o 'i' o ~

* N

B

FC- 2

1 1/2" S- l

o

~ ro

9 l!l

I Sf-2 Hod , ST I ARS-C - I r i o 'i' N ~ M

o

~ N M

~ N ro M

'-

., ;;- ... . -.: " '. c.,.,'.· .. ,' ,7 ' ' '':

.. .. ,-.,'"

FIGURE 2

Typical Cracks in Exist ing Pavement

24

FIGURE 3

Crumb Rubber

•

""'-" -~

FIGURE 4

Conveying Crumb Rubber and Mixing With Asphalt Cement (AC-20) in the Distributor Truck

25

FIGURE 5

Applying Asphalt-Rubber Membrane

FIGURE G

Spreading Chips on Asphalt-Rubber Membrane

26

FIGURE 7

Rolling Asphalt -Rubber Seal Coat

FIGURE 8

Surface Text ure of Asphalt -Rubber Seal Coat

27

_FIGURE 9

Pre-coat ed Slag Chips for Seal Coat

FIGURE 10

Surface Te xture - Type II Modified Surface Treatment

28