Hot mix asphalt design

7/30/2019 Hot mix asphalt design

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Tenth Edition 2008

HOT MIX ASPHALT

PAVEMENT DESIGN

GUIDE

Th e Maryland Asp h alt Association , Inc .


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Requirements

for Successful Asphalt

Pavement Construction1 GOOD PLANNING

2 GOOD DESIGN

3 GOOD CONSTRUCTIONA) Materials

B) Subgrade

C) Workmanship

4 GOOD MAINTENANCE

published for

Maryland Asp ha lt Associa tion, Inc .

2408-G Pepp er Mill Drive, Glen Burn ie, MD 2106 1

410-761-2160 Fax 410-761-0339

Editor: Brian Dolan

Auth or: Brian Dolan

pub lishe d by

P/ T Enterp r ises , Inc.

Fallston , MD 210 47

410-879-7606 Fax 410 -893-5721

p r in te d b y

E. John Schmit z & Sons , Inc.

Sparks, MD 21152

410-329 -300 0 Fax 410-771-4342


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INTRODUCTION

This guide is pro vided by the Maryland Asph alt Association as a tool for ow ner s, architects, enginee rs and develop ers wh en

preparing plans and specifications for pavements to be constructed in Maryland.

The guide is not intend ed to be used as a substitute for p rofessional asph alt p avement design by co mp etent e ngineers using

spec ific traffic and soils information. By nece ssity this manual uses generalizations and simp lifications; ho we ver, the u se of these

designs and sp ecifications,together with p roper construction co ntrols, will provide users with econo mic and satisfactory

pavements that will provide good performance with relatively little maintenance.

The tenth edition of this guide has been prep ared in order to bring designers information on the c urrent Maryland State Highway

Administration Specifications and to incorp orate the latest know ledge, techniques and technology that h ave been

developed in asph alt p avemen t construction over th e p ast several years. This pub lication is not intended to set standards or

regulations. The roadway typical sections are Perpetual Pavements and have been verified using the Per Road

Flex ib le Pe rp et ua l Des ig n & Ana lys is Sof tw are.

HOT MIX ASPHALT

WHAT IS HOT MIX ASPHALT?

Hot mix asphalt may be referred to by several names. In

differen t sections of the state it may also b e referred to as

bituminous concrete, hot plant mix, asphalt concrete,

blacktop or Superpave.

Hot mix asphalt is comp osed of aggregate boun d together

into a solid mass by asph alt ceme nt. The aggregates total

ninety-three (93) to ninety-seven (97) percent by weight of

the total mixture and are mixed w ith three (3) to seven (7)

percen t asph alt cement. It is manufactured in a central

mixing plant whe re the asphalt and aggregates are heated,

properly proport ioned, and mixed. The completed paving

mixture is hauled by trucks to th e mech anical spreader w here

it is placed in a smooth layer and compacted by rollers while

stil l hot. (Hot mix asphalt may be placed by h and w hen it is

impractical to use a paver.)

Asphalt pavemen ts are con structed of one or more co urses

of hot m ix asph alt placed directly on th e subgrade or on

a subbase.

HOT MIX ASPHALT SPECIFICATIONS

All wo rk involving hot mix asph alt p avemen ts and resurfacing

can be covered by using the Maryland State HighwayAdm inistration July 200 8 Stand ard Spe cifications for

Construction and Materials in conjunction with the typical

sections th at follow.

HOT MIX ASPHALT RESURFACING

Resurfacing is the placing of one or more courses of hot mix

asphalt over an existing hard surface p avemen t. This is the

most often used means for salvaging and extending the

service life of older d eteriorating p avemen ts.

ADVANTAGES OF HOT MIX ASPHALT

1. Versatility

Hot mix asphalt pavements can be designed to

hand le virtually any traffic loading, soils and

materials, and can be used to salvage old p avemen ts

as well as to build new ones.

Phased construction can easily be incorporated.

2 . Ec on o my

Hot Mix Asph alt Pavemen ts are:

economical to construct may be con structed rapidly and are immediately

ready for use

may be recycled

require minimal maintenance

provide outstanding performance

3. HMA pavements are not affected b y ice controlchemicals.

4. Building and site esthetics are enhanced.

5. Traffic no ise is minimized w hen HMA pavement

is u se d .

6. Pavement striping is highly visible on th e dark

colored surface.

7. HMA is a flexible-type pavem ent.


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SUPERPAVE

Superpave is a state of the art paving system which our industry and the state of Maryland embraced in

the late 1990s. Marshall mixes are no longer readily available and should b e rep laced w ith the appro pri-

ate Sup erp ave specifications.

There are four imp ortant Sup erpave parameters w hich the ow ner m ust specify in order to insure theprop er design. These parameters include the type of liquid asph alt wh ich, in all but the m ost unusual

circum stances sho uld be PG 64-22; the com pac tion level shou ld be N Design 50 or Level 1 for all

applications excep t minor or p rincipal arterial streets. The next tw o parameters go hand in hand and

shou ld always be co nsidered togeth er. Aggregate size and lift thickn ess are insep arable. All mix selections

shou ld allow for at least 4 times the n om inal max imum aggregate size for th e desired lift thickness. This

means 9.5mm aggregate surfaces should be a m inimum of 1-1/2 thick.

Please con sult with the Maryland Asph alt Association for guidanc e in sp ecifying the pr op er sup erp ave

spec ification for your individual p roject.

SPECIFICATIONS FORHOT MIX ASPHALT

There are a wide variety of hot mix asphalt compositions used

in Maryland th at vary from fine to c oarse in size and

gradation. Furtherm ore, Maryland hot mix asphalt mixtures

utilize differen t aggregates or comb inations of aggregates, the

principal types being crushed stone, sand, gravel, bank run

gravel, roofing shingles and recycled asph alt pavem ent.

Econ omics req uire th e u se of locally available aggregates.

The most widely used hot mix asphalt specifications in

Maryland are those contained in the State HighwayAdministration Standard Spe cifications for Con struction

and Materials dated July 2008 including re visions

and additions.

The Maryland Asph alt Association reco mm end s the use of

these specifications.

BASE DESIGNATIONS

19 MM Sup erp ave

Gene rally a minimum lift thickness of 3" is recomm end ed.

Aggregate sizes of the mix design should be checked prior

to u se in thinn er lifts.

12.5 MM Sup erp ave

Gene rally a minimum lift thickness of 2" is recomm end ed.

Aggregate sizes of the mix design should be checked prior

to u se in thinn er lifts.

SURFACE DESIGNATIONS

9.5 MM Sup erp ave

This surface mix is recommended for most surface

applications.

Recommen ded minimum lift thickness 11/2".

4.75 MM Sup erp ave

This mix is designed pr imarily for thin lift leveling o r

correcting minor deviations. It is a fine mix that can be

placed in lifts as thin as 1/2". It should not be placed in

lifts exceeding 1" and sho uld no t no rmally be sp ecified

as a final wearing cou rse for structu ral repairs or

resurfacings.

SMA (Ston e Matrix Asph alt)

This is a high stability mix d esigned for spe cific con ditions

such as high volume Interstate Highways.


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A m odern ho t m ix asphalt facilit y prov ides h igh

produ ction , good qu ality m ixes ( in cluding recy cled

asphalt pavem ent if desired) w hile meeting stringent

air qu ality stan dards.

ASPHALT PAVING MIXTURES

The pavement design requires the p roper h ot mix asphalt

paving mixtures for the base and surface pavements.

It is impor tant th at a Job Mix Formu la for th e p aving

mixture be established for and approved b y the en gineer.A reputable h ot m ix asphalt producer, providing standard

mixes, can readily furnish the engineer w ith a w ritten Job

Mix Formula.

The asphalt mixtures referred to in this manual are Maryland

State Highw ay Adm inistration Job Mix Designs w hich are

readily available throu ghou t Maryland an d h ave proven

through extensive use to have all of the desirable

characteristics of good asphalt pavements.

SPECIFICATIONSMaryland State Highway Administration Standard

Spe cifications for Constru ction an d Materials, dated

July 2008, including revision s and additions,

con tain the following section s for Hot Mix Asph alt Pavemen t

and Asph alt Cemen ts and Hot Mix Asph alt:

Section 504 Hot Mix Asph alt Pavem ent

Section 505 Ho t Mix Asp halt Patch es

Sect ion 508 Milling Existing Hot Mix Asph alt

Pavement

Section 901 Aggregates

Section 904 Performanc e graded asphalt bin &

HMA

Section 915 Produ ction Plants

Se c tio n 9 15 .0 2 Ho t Mix Asp h a lt Pla nt s

TACK COATA tack coat of asph alt (usually em ulsified asphalt) is app lied

to ensure bo nd b etween the existing surface and the asphalt

overlay. It should be ap plied in an even, thin coat at a rate ofapplication of .05 gallons per square yard with a tolerance of

.01 gallons per square yard. Excessive tack coat can cause

slipp age or can flush to the surface. All longitudinal and

transverse joints shall be properly tacked.

SUBGRADE SPECIFICATIONS

Top soil, large rocks and oth er types of low q uality, unsu itable

soil shall be remo ved and replaced. The subgrade must be

prop erly shaped to the d esired sections and elevation and

shall be comp acted so that i t is firm, hard and un yielding. A

firm an d un yielding subgrade is essential for good p avemen t

construction. The Subgrade shall be comp acted to 95% of

dry w eight d ensity as deter mined by AASHTO Designation

T-18O, Method C or D as applicable. (Note:There are areas in

Maryland w here, due to the type of soil ,i t is not po ssible to

attain 95% of dry w eight den sity using the T-180 Metho d. In

these areas the co mp action requirements shall be 95% of the

dry w eight d ensity as deter mined by AASHTO Designation

T-99 Method.) To prevent grow th of weed s, the subgrade

should be treated with an app roved herbicide. (See NAPA

Pub lication IS-51)

ENGINEERING SERVICESThe Maryland Asph alt Association w elcome s the o pp ortu nity

to work w ith architects,co nsulting engineers, pub lic agency

officials, own ers, and industry engineers in the p reparation ofpavement specifications,co nstruction d etails and co nstruction

controls toward the end of quality asph alt pavemen t

installation s. The Association h as professional engine ering

services available for th is purp ose. The Associations add ress

and te lephone n umber appear on the back cover. Other

sources where information and guidance on asphalt pavement

construction may be ob tained are:

Nat ion al Asph alt Pavem ent Association

5100 Forbes Boulevard

Lanha m , Maryland 20706-4413

(301 ) 731-4748 FAX(30 1) 731 -4621

The Asphalt In stituteCarlos Rosen berger

PO Box 337

2 E.Ha rrisburg St.

Dillsbu rg, PA. 17019

717-432-5965

The Asphalt In stitute

P.O. Box 140 52

Lexin gton , Kentu cky 40512-4052

859-288-4960

ESTIMATING QUANTITIESFor a cursory estimate of the quantity of material required,

use1 ton of hot mix asph alt covers 17 square yards, l" thick.


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Chart 1: Recomme nded Mixes for Normal HMA Applications ( Propose d compact ion le vels based on NCHRP 9-9 levels @ 4% Per Voids)

Low Volume Design Level

Recommen d ed

Aggre gate Siz e Binde r Type Co m pactio n Le ve l Co m pacte d Thickn e s s

Surface 9.5m m PG64-22 50 gyrations 1.5

Base 12.5m m PG64-22 50 gyrations 219m m PG64-22 50 gyrations 3

Minor Arterial Design Level

Aggre gate Siz e Binde r Type Co m pactio n Le ve l


Base 12.5m m PG64-22 50 gyrations 2

19m m PG64-22 50 gyrations 3

High Volume Design Level

Aggre gate Siz e Binde r Type Co m pactio n Le ve l


9.5m m PG76-22 65 gyrations 1.5

9.5m m SMA PG76-22 80 gyrations 1.5

12.5m m SMA PG76-22 80 gyrations 2

Base 12.5m m PG64-22 65 gyrations 2

19m m PG64-22 65 gyrations 3

Reco m m en ded Mix Designs

MAA Chart 1


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Traffic

Des ignation Typical Roadway ApplicationsEquivalent Single

Axle Loadings

Low

Moderate

High

< 300,000 ESALs

300,000 to < 10,000,000

ESALs

> 10,000,000 ESALs

Roadways with very light traffic volumes such as local roads, coun ty

roads, and city streets wh ere truck traffic is prohibited or at minimum.

Traffic considered local in nature, not regional, or interstate.

Special purp ose roadw ays serving recreational sites or areas.

Most local roadways.

Two-lane, multilane, divided, and p artially or c omp letely controlled

access roadw ays.

Medium to h ighly trafficked city streets, state routes, U.S. highways,

and some rural interstates.

Two-lane, multilane, divided, and p artially or c omp letely controlled

access roadw ays.

Medium to h ighly trafficked city streets, state routes, U.S. highways,

and some rural interstates.

Truck -we ighing stations or tru ck-climbing lanes on tw o-lane roadw ays.

Chart 2: Traffic Volum es

PAVEMENT DESIGNThe design of a hot m ix asph alt pavement requires some

knowledge of the following:

TRAFFIC

DRAINAGE

SUBGRADE SOILS SUPPORT

TRAFFIC

Asphalt pavements must be designed using the prop er

num ber and weight of axle loads expected during a given

period of time to insure adequate pavement p erformance.

Of primary conce rn is heavy truck traffic. Pavement life can

be significantly affected b y truck traffic, there fore, the w eight

and volum e of th e h eaviest traffic is a princ ipal factor in

pavement design. The following traffic assumptions h ave

been made for the p urpo ses of providing typical pavement

sections for the follow ing:

TYPICAL PAVEMENT SECTION 2Residential Drive

Essentially limited to passenger cars.

TYPICAL PAVEMENT SECTION 3 Park ing Lot s & Reside nt ial

or Light Du ty Streets p resent and futu re traffic limited to

passenger cars plus normal service trucks.

TYPICAL PAVEMENT SECTION 4Minor Arterial & Light

Industrial Streets p resent an d future traffic limited to a

medium duty classification which includes some heavy

truck and bus traffic.

TYPICAL PAVEMENT SECTION 5Principal Arterial,

Comm ercial or Ind ustrial Roads presen t and futu re traffic

is a heavy duty classification.

DRAINAGEProper drainage is imperative in the design and construction

of hot m ix asph alt pavements.

Where high w ater tables occur or w here w ater may

accumulate in low areas, consideration must b e given to

subsurface drainage. The installation of unde rdrains and/ or

interceptor drains may be requ ired to prevent the

accumulation of water ben eath the p avemen t structure.

Good surface drainage is also essential. A minimu m slope or

crown o f 1.5% per foot is recom mend ed. The roadway

shoulder or adjacent ground sho uld be graded so th at surface

drainage runs away from th e p avemen t and doe s not stand on

the p avement's edge.

On large parking lots,sloped sections, catch basins, and storm

drains may be necessary for proper drainage.

TABLE ISoil Classification Strengths:

MAA Chart 2


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Chart 3: Gene ral Ratings of Soil Quality

6

SUBGRADE SOILSA FIR M AND UNYIELDING SUBGR ADE IS

ESSEN TI AL TO GOOD PAVEMENT CONS TR UCTION.

For th e designs reco mm end ed in th is manual all soils are

divided into th ree classes: Good (G), Medium (M) and

Poor (P).

California Bearing Ratio (CBR) design values are assigned for

each class.

It is desirable to u se laboratory tests to e valuate th e load-

suppo rting characteristics of subgrade soils. However, if

laboratory test equip men t is not available, designs may be

made on the basis of a careful field evaluation b y an enginee r

who can assign the subgrade soils to one of the following

categories:

(G) GO OD SUBGRADE SOILSGo od sub grade soils retain

a substantial amount of their load bearing capacity when

wet. Included are the clean sands and sandy gravels and

soils free of detrimen tal amou nts of plastic materials. Agood subgrade will have a CBR value of 20 o r highe r.

(M) MEDIUM SUBGRADE SOILSThese retain a moderate

degree of firmness under adverse m oisture co nditions.

Included are such so ils as loams, silty sands and sandy

gravels containing m ode rate amo unt s of clay and fine silt.

A medium classification will have a CBR value of 6

through 20.

(P) POO R SUBGRADE SOILSThe se so ils bec om e q uite

soft and plastic when wet. Included are those soils having

app reciable amoun ts of clay and fine silt. The co arser silts

and sandy loams also may exhibit poo r bearing p roperties

in areas where frost pen etration into the subgrade is afactor. A poor classification w ill have a CBR value of 5 o r

less. Soils with a CBR value of less than 5 sho uld b e

stabilized or removed and replaced using suitable material.

A stable subgrade is always requ ired.

The add ition of soil stabilizers such as Portland Cemen t or

lime to th e p aving sub -grade alters the soil in several ways.

1. Reduction of p lasticity of the soil

2. Promotes imme diate structural changes in the soil

3. Adjusts the moisture - den sity relationsh ip

4. Promo tes sub-grade soil strength and incre ased CBR values

The end result is a sub-grade soil that provides an enhancedplatform for placing new paving.

California Bearing Ratio (CBR) is a test used for evaluating

bases, subgrades and subbases for p avemen t thickness design.

The correlation chart above may be used w hen o ne of the

system values indicated is known.

The Asph alt Institut e's "Soil Manual for Design of Asph alt

Pavemen t Struct ures" Series No. 10 (MS 10), describe s in detail

the commonly used soil evaluation systems and test proce-

dures. Field evaluation o f the soil involves visual insp ection

and simp le field tests.

California

Bearin g RatioR Valu e

Highw ay Soil

Classification

Unified Soil

ClassificationRelative Q uality

High Q uality

Good

Weak

Ver y Poor

Greater th an 80 Greater th an 70

55 to 80 20 to 70

5 to 20

Less than 5

A-1

A-4,A-5

A-6,A-7

GW, SW, GP, GM

OH,CH,CL

ML, OL, MH

SW, SP, SM, SCA-2,A-3

25 to 55

Less than 25

MAA Chart 3


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Hot mix asph alt recycling is a proven tec hn ology. It is cost

effective, mee ts all specifications and th e qu ality of the

recycled asphalt pavement has been proven to b e equal to

conventional mixes. When u sing reclaimed asphalt pavement

(RAP) in HMA, the virgin aggregate and asphalt are redu ced,

therefore a savings can be realized. In addition the u se of rap

or reclaimed asphalt materials aids the environment.

Recycling may include the use of glass,p lastic, asphalt, asphalt

shingles, and p aper.

The use of reclaim ed m aterial is less expensive than usin g all virgin aggregate and asphalt. Cold m illing

existing asphalt pavem ents allow desired section a nd grade to be established. It can also be used to ma in tain a

desired height of curbs and bridge clearan ces when overlaying existing roadways. Existing pavem ents m ay be

removed by the cold milling process.

Removal of badly deter iorated pavemen ts, surface

irregularities and maintaining curb reveal, etc. can b e

economically accomplished with minimal disruption to traffic

using the cold milling or carbide grinding p roce ss. The RAP

obtained through these proc esses can be recycled in a cost

effective rehab ilitation pro cess. (Maryland State Highw ay

Administration Standard Spe cifications for Co nstruc tion an d

MaterialsSect ion 508 Milling Existing Hot Mix Asph alt

Pavement)

HOT MIX ASPHALT RECYCLING


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SIDEWALKS, GOLF CART PATHS,

BIKE PATHS

SUBGRADE

Subgrade soils must be evaluated to determine theload-supp orting character istics. Refer to page 6.

The subgrade must be p roperly shaped to the desired

section and elevation and shall be co mp acted. Refer to p age 6.

DRAINAGEGood subsurface and surface d rainage is essential to

quality hot mix asphalt pavements. Refer to page 5.

HOT MIX ASPHALT CONSTRUCTION

A single course of 9.5 mm m ixture is recommen ded d ue to

the confined areas generally involved where constructing

Sidewalk, Golf Cart Paths or Bike Paths excep t wh ere p oorsubgrade is encountered. Hot mix asphalt shall be designed

mixed and constructed in accordance with Maryland State

Highway Administration Standard Specifications for

Constru ction an d Materials, July 2008 including revisions and

additions.

CONSTRUCTION DETAILS

Subgrade

Class

Good

Medium

Poor

Surface Cou rse

CompactedThickness

DesignLevel

SuperpaveMix

3

4

Low Volum e

50 Gyrations

Low Volum e

50 Gyration s

9.5 MM

9.5 MMSurface Cou rse

8

9.5 mm Surface should be placed by a paver.

Hand w ork should b e restricted wh ere feasible.


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RESIDENTIAL DRIVES,

PLAY AREAS

PAVEMENT WIDTHResiden tial driveways for a single automo bile, the

pavement should be a m inimum 10' in w idth.

The minimum radius for a right angle whe re the driveway

meets the street is 10'.

SUBGRADESubgrade soils must be evaluated to determine the

load-supp orting character istics. Refer to page 6.

Top soil must be rem oved and subgrade p roperly shaped to

the d esired section and e levation and shall be c omp acted.

Refer to page 5. Treat the subgrade w ith an approved

herbicide to inhibit future weed growth.

AGGREGATE BASE CONSTRUCTIONIn certain situations graded aggregate base construction may

be d esirable. See "Pavemen t Base Course Equivalency" page

16 for recomm ended thickness.

DRAINAGEGood subsurface and surface drainage is essential to qu ality

hot m ix asphalt pavements. Refer to p age 5.

TACK COATRefer to page 3.


Hot mix asphalt shall be designed, mixed and

constructed in accordance with Maryland State Highway

Adm inistration Standard Spe cifications for Constru ction

and Materials, July 2008 including revision s and

additions.

The hot mix asphalt base may be placed in a single course to

the req uired thickness. Small mechanical pavers are

available for this type o f construction. When ever possible,

hand placement should be avoided. However, where access

to the work area is l imited, hand p lacemen t may be the only

feasible method.

SUGGESTIONS FOR OBTAINING A QUALITY RESIDENTIAL DRIVEWAY PAVEMENTSelect con tractors know n for quality work and established rep utations in the com mu nity. Ask for local references.

Insist on a written con tract or agreemen t. Spe cify mater ials and w orkm anship in accordan ce w ith Maryland State Highw ay

Administration Spe cifications. Spe cify a minimum c om pacte d thickne ss.


Subgrade

Class

Good

Medium

Poor

Base Cou rse

Subgrade CBR or Greater than 20

Surface Co ur se

Compacted

Thickness

1 12

2 12

1 12

Base Cou rse

Sub grade CBR 5

Surface Cou rse

3 12

Low Volum e

Low Volum e

Low Volum e

Low Volum e

9.5 MM

12.5 MM

9.5 MM

12.5 MM

Superpave

Mix

Design

Level


12/20

PARKING LOTS, RESIDENTIAL

OR LIGHT DUTY STREETS,

STORAGE AREAS

DESIGN CRITERIA < 1 0 0 0 ADT 1 % TRUCKS

SUBGRADE

Subgrade soils must be evaluated to determine the


The subgrade must be p roperly shaped to the desired

section and elevation and shall be co mp acted. Refer to p age 6.

DRAINAGE

Good subsurface and surface d rainage is essential toquality hot mix asphalt pavements. Refer to page 5.

TACK COAT

Refer to p age 3.

HOT MIX ASPHALT CONSTRUCTIONHot mix asphalt shall be designed, mixed and


Administration Standard Spe cifications for Co nstruc tion an d

Materials, July 2008 including revisions and add itions.

The hot m ix asph alt base may be p laced in a single course. A

total thickness of up to 4.5" of base mix may be placed in one

lift. If several cou rses are desired or if job spec ifications

require several courses,it is recommen ded that the first base

course be 3" minimum depth.

An intermediate course of 9.5mm should be added to red uce

permeability and increase durability during construction if thefinal surface is not sch edu led un til subdivision build out.


Subgrade

Class

Medium

Poor

Base Cou rse

Subgrade CBR 20 or Greater

Surface Co ur se

Compacted

Thickness

Superpave

Mix

1 12

3 12

1 12

Base Cou rse

Sub grade CBR 5

Surface Cou rse 1 12

5 12

Base Cou rse

Subgrade CBR 6-20

Surface Cou rse

4 12

Good9.5 MM

12.5 MM

9.5 MM

12.5 MM

9.5 MM

19 MM

0

Low Volum e

Low Volum e

Low Volum e

Low Volum e

Low Volum e

Low Volum e

Design

Level


13/20


MINOR ARTERIAL AND LIGHT

INDUSTRIAL STREETS

DESIGN CRITERIA < 2 5 0 0 ADT 3 % TRUCKS

SUBGRADE



The subgrade must be p roperly shaped to the desired section

and elevation and shall be co mp acted. Refer to p age 6.

DRAINAGE

Good subsurface and surface d rainage is essential to quality

hot m ix asph alt pavements. Refer to p age 5.

TACK COAT

Refer to p age 3.


Hot mix asphalt shall be de signed, mixed and c onstructed in

accord ance w ith Maryland State Highw ay Adm inistration

Standard Spe cifications for Constru ction and Materials,

July 2008 includ ing revisions an d add itions.

The ho t mix asphalt base may be placed in a single cou rse.A


lift. If several cou rses are desired or if job spec ificationsrequire several courses,it is recommen ded that the first base

course be 3" minimum dep th.


Subgrade

Class

Medium

Poor

Base Cou rse

Surface Cou rse

Compacted

Thickness

Superpave

2

4

2

Base Cou rse

Sub grade CBR 5

Surface Co ur se 2

6 12

Base Cou rse

Subgrade CBR 6-20

Surface Co ur se

5

Good9.5 MM

12.5 MM

9.5 MM

12.5 MM

9.5 MM

19 MM

Minor

ArterialMinor

Arterial

Minor

ArterialMinor

Arterial

Minor

ArterialMinor

Arterial

Design

Level


14/20

PRINCIPAL ARTERIAL,

COMMERCIAL OR

INDUSTRIAL ROADSDESIGN CRITERIA < 4 LANES,1 0 ,0 0 0 ADT,

6% TRUCKS

SUBGRADE





DRAINAGE

Good subsurface and surface d rainage is essential to

quality hot mix asphalt pavements. Refer to page 5.

TACK COAT

Refer to p age 3.


Hot mix asphalt shall be designed, mixed and


Administration Standard Spe cifications for Con struction

and Materials, July 2008 includ ing revisions an d

additions.

The hot m ix asph alt base may be p laced in a single course. A


lift. If several cou rses are desired or if job spec ifications

require several courses,it is recommen ded that the first

course be 3" minimum dep th.


Subgrade

Class

Medium

Poor

Base Cou rse


Surface Cou rse

Compacted

Thickness

Superpave

2

7

2

Base Cou rse

Sub grade CBR 5

Surface Co urse 2

9

Base Cou rse

Subgrade CBR 6-20

Surface Co ur se

8

Good12.5 MM

19 MM

12.5 MM

19 MM

12.5 MM

19 MM

2

High Volum e

High Volum e

High Volum e

High Volum e

High Volum e

High Volum e

Design

Level

* Mix Selection: Please re fer to NAPA pub lication IS 128 for furthe r d esign assistance.


15/20

TENNIS & MULTI-USE COURTS,

RUNNING TRACKS

SUBGRADE





TACK COAT

Refer to p age 3.


Hot mix asphalt shall be de signed, mixed and c onstructed inaccord ance w ith Maryland State Highw ay Adm inistration

Standard Spe cifications for Constru ction and Materials,

July 2008 includ ing revisions an d add itions.

A specia l m ix other than 9.5 m m m ay be used for the su rface course for ru nnin g t rack s.There are sev eral

resilient hot m ixes available which com bine rubber aggregate w ith regular aggregate plus a high asphalt con-

tent. Specifications an d technical assistance are available from the firm s that fu rnish the special aggregate.

The ho t mix asphalt may be p laced w ith a mechanical paver

or by hand, if the contractor elects. In either case, for tennis

court con struction, the finished course must not vary from

line, grade or cross-section mo re than l/8" in 10' whe n

measured in any direction. For runn ing tracks,the finished

course m ust not vary more than 1/ 4" in 10'.

Proprietary surfacing is available for tennis courtsand running tracks . Most mem ber s of The Maryland

Asph alt Association are familiar w ith th e various mater ials and

can p rovide information on them or it may be ne cessary to

contact the manufacturer directly.

DRAINAGE

The finished tenn is cou rt surface should slope l" in 10', 0.83%,

on a true plane from end to end, corner to corne r, or side to

side. Side to side is pre ferable for a p laying surface and for

construction. The surface should not slope to th e net or away

from th e net in more th an one direction.


Subgrade

Class

Good

Medium Leveling Cour se

Base Cou rse

Surface Cou rse


Compacted

Thickness

1.5

1.5

2

Super Pave

9.5 MM

9.5 MM

12.5 MM

Poor Leveling

Base Cou rse

Surface Cou rse

Subgrade CBR 3-5

1.5

1.5

2

9.5 MM

9.5 MM

12.5 MM

Low Volum e

Low Volum e

Low Volum e

Low Volum e

Low Volum e

Low Volum e

Design

Level


16/20

Asph alt overlays are the mo st comm on , practical and

econo mical way to salvage, strengthen and mode rnize

old pavements.

Properly designed, constructed and m aintained h ot

mix asphalt pavement resurfacings offer the following

advantages:

1. Strengthen existing p avement structurally

2. Reduce maintenance app reciably

3. Exten d service life app reciably

4.Allows use of roadway while improvements are in progress

5. Provides safer p avemen ts

6. Improve ride quality and appe arance

7. Reduced energy costs

8. 100% Recyclable

9. Provides noise reduction

RESURFACING CONSID ERATIONS

The ke y to suc cessful resurfacing is careful evaluation of theexisting pavement and the selection of an adeq uate

pavement de sign. The following information shou ld be

considered: 1. Physical con dition including surface condition

and structu ral adequ acy. 2.Type of con struction of existing

pavem ent 3. Drainage of existing pavement 4. Load and traffic

use (weight and volume of heaviest traffic) of present and

future traffic.

The thickness of the overlay is designed to improve a lower-

than-average pavemen t cond ition, but n ot to p rovide the extra

strength ne eded for localized, structu rally we ak areas. Sho uld

the overlay thickness be based on the w eakest condition in

the section, it would be overdesigned for the rest of the

section, and more costly. The proper pro cedure is to correct

the w eaker areas. Removal of structurally weak areas and

patching w ith full-dep th h ot m ix asphalt to ensure strength

equal to or exceeding the surrounding pavement is an eco-

nomical means of preparing for overlays.

A minimum thickness of 4 12" of hot m ix asphalt is

recomm ended for rigid pavement overlays.

PAVING FABRICPaving fabrics are available for use w ith HMAo verlays. When

placed between the original pavement and the HMA overlay

or betw een tw o cou rses of an HMA overlay it becomes an

integral part of the roadway section. When p roperly used, fab-

rics reduce w ater infiltration and reflective c racking. Thereare several pro pr ietary fabrics available w hich sh ould b e

installed in accordance with the manufacturers instructions.

The addition of the correct fabric into a pavement overlay

reduces the effect of mech anisms w hich deteriorate pave-

ments and increases the life of the overlay pavement section.

Paving Fabrics Shou ld:

Meet AASHTO M288 guidelines for paving fabrics

Provide a w aterproof barrier for subgrade protection

Improve the fatigue resistance of the new overlay by

pro viding a stress relieving interface

Retard the propagation of an existing crack through

the new overlay (reflective cracking)

Exten d th e useful life of the o verlay

Be able to w ithstand the high temp erature of asph alt

Strengthen the en tire p avemen t section

Can be used o ver milled surfaces and are m illable &

recyclable onc e installed

A Certificate of Com pliance for the paving fabric used on anyproject should be furnished by the manufacturer to the engi-

neer. The p aving fabric shall be sup plied in a p rotective cover

that is capable of p rotec ting the fabric from u ltraviolet rays,

abrasion and water. Paving fabric should meet or exceed

AASHTO M288 guide line s.

Asphalt Sealant: The en gineer shall app rove theasphalt cemen t. A grade of asphalt of the same type u sed in

the manufacture of the hot mix asphalt for the overlay should

be acceptable.

EQUIPMENT:

Asph alt Dis tributor: The distributor must be suitablymetered and capable of spraying the asphalt cement uniform-

ly and at the prescribed application rate.

Fabric Handling Equipm en t: A tractor or similarmech anical device w ith m ounted laydown e quipmen t that is

capab le of handling full rolls of fabric shall be u sed. The

equipment shall be capable of laying the paving fabric

smoothly without excessive wrinkles and/or folds.

Miscel laneous Equipment: Stiff bristle broomsused to smoo th, and scissors (or blades used to cut th e paving

fabric shall be pro vided b y the installer.

INSTALLATION PROCEDURE:

Surface Preparation: The surface on w hich thepaving fabric is to be p laced shall be free of dirt, wate r,vegeta-

tion and other foreign materials. Open cracks 3/8 inch or

larger shall be filled w ith sand m ixed asph alt as directed b y

the en gineer. Cracks larger than 3/ 8 inch or h oles shall be

filled w ith cold or ho t mix asphalt . The use of a leveling

course may be required prior to placing the paving fabric in

severe cases.

Application o f Seal ant: The asphalt cemen t andbinder must be uniformly spray-applied at the specified rate.

The qu antity required may vary with the surface con dition of

the existing p avemen t (e.g. degree of porosity), but shall be

applied at a nominal rate of 0.25 gallons per square yard of

residual asphalt.

App lication of asphalt cem ent w ill be p erformed by truck-

moun ted distribution equipm ent wh enever possible, with

hand spraying kept to a minimum.

Paving Fabric Placem en t: The p aving fabric shall beplaced onto the asphalt cemen t with a minimum of wrinkles

before the asphalt can cool or lose its tackiness.

4

HOT MIXASPHALT RESURFACING


17/20


Hot mix asph alt shall be de signed , mixed and co nstruc ted in accord ance w ith Maryland State Highway Adm inistration Standard

Spe cifications for Construction and Materials, July 2008 includ ing revisions and additions.

The paving fabric shall be placed so that the non-heat treated

(bearded or fuzzy) side is placed downward into the sealant,

thus providing optimum b ond b etween fabric and p avement

during the construction process. As directed by the engineer,

wr inkles severe eno ugh to cau se foldssh all be slit and laid

flat in the direction o f paving op erations. Brooming the

paving fabric will assist in m aking intimate con tact w ith the

pavement surface.

Any overlap of the paving fabric should be minimized,

although an overlap of 1 to 3 inches is recommen ded to

insure full closure of overlapp ing layers. Transverse joints

should be shingled (overlapp ed) in th e direction of paving

operations to prevent edge pick-up by the paver.

NOTE: In the event th at asph alt cemen t should bleedthrough the p aving fabric be fore the hot m ix asph alt is

placed, it may be n ecessary to absorb any visible sealant by

spreading sand or h ot mix asphalt over those areas. This

should minimize the tendenc y for construction equipm ent

tires to lift the paving fabric wh en dr iving over it. Turn ing of

paving equ ipment and oth er vehicles on th e p aving fabric

must be kep t to a minimum to avoid movemen t or damage to

the fabric.


HIGH VOLUME SINGLE LIFT RESURFACING

Old Pavemen t

Surface Co ur se

Average

Compacted

Thickness

Superpave

2

1 12

12.5 MM

9.5MM

Old Pavemen t

Surface Cou rse

Refer to MAA Char t 1


Design

Level

TACK COAT

Refer to page 3

A tack coat of asphalt (usually emulsified asphalt) is applied

to ensure bo nd b etween the existing surface and the asphaltoverlay. It should be applied in an e ven, thin coat at a rate

of application .05 gallons per squ are yard. Exce ssive tack coat

can cause slipp age or can flush to the surface.

All longitudn al and transverse co nstruc tion joints shall be

prop erly tacked.


MULTIPLE LIFT RESURFACING

Base Cou rse

Leveling (wh en required)

Surface Cou rse

Old Pavement

Average

CompactedThickness

1 12

Design Thickness

1= (variable)

Superpave

9.5 MM

19.5MM

9.5 MM*

Leveling Co ur se

Surface Cou rse

Old Pavement

1 12

1= (variable)

9.5 MM

9.5 MM

* If Wedge and Level course exce eds 3 you may con sider going to 12.5 mm W/ C course.






DesignLevel


18/20

EQUIVALENCES

Consideration may be given to a pavement section using a

graded aggregate base cou rse with a h ot mix asph alt binder

and surface course. Maryland h as several excellent aggregate

sources that may m ake locally available aggregate an

econo mic alternative. All graded aggregate base should mee t

Maryland State Highway Administration Specifications for

Construction and Maintenance, July 2008 including

revisions an d add ition s.

Paving mater ials have differen t ab ilities to sustain the loads to

wh ich they are subjected. Relative strength values of the

various materials used in asphalt pavements have been

evaluated so that it is possible to d evelop d esigns with

different com pon ents to give com parable pavemen t

performance. The AASHTO Design Committee from road test

findings e stablished a list of coe fficients of pavem ent

comp onen ts for surface, base and subbase courses. The use of

these coefficients permits equating materials into inches of

one com pon ent to inches of another in the asphalt pavement

structures.

The criteria established in th e AASHTO Guide for Design of

Pavemen t Structu res,The Asph alt Institute's "Thickness DesignManual" MS-1, The Nation al Asph alt Paving Association 's

IS-129 and IS-132 , and The Maryland Asph alt Association 's

experience with millions of square yards of pavements con-

structed in Maryland were considered and utilized in part to

develop the pavement designs and material equivalences

used in this manual.

Asphalt pavements must retain a minimum thickness of hot

mix asphalt surfacing (including b inder cou rses) whe n used

on granular bases. Minimum surface thicknesses should be

increased with increased weight and volume of traffic and

when used on poor subgrades.

PAVEMENT BASE COURSE EQUIVALENCYONE INCH HOT MIX ASPHALT BASE COURSE EQUALS 2 12''

CRUSHER RUN O R GRADED AGGREGATE BASE. RCR-6

(CRUSHED CONCRETE OR RCR-6 (MILLED HMA).

OTHER USES FOR

HOT MIX ASPHALT

There are a wide variety of uses for hot mix asphalt mixes

and/or p avemen ts that are not l isted or shown elsewh ere inthis guide. The same basic pr inciples used for con structing

successful pavements would apply to installing pavements for

other uses. Some p avement or mix modifications might be

required, but are generally, minor in nature. Some of the other

uses for th e p roduct follow:

AIRFIELDSRunways

Taxiways

6

NAPA and The Asphalt Institute publications are available for specialized mix design and placement techniques.

MOTOR SPORTS RACE TRACKSSpecialty mixes not included in MAAs

Recommended mixes for normal HMA applica-

tions(Chart 1) may be requ ired. NAPA,The

Asphalt Institute and automotive sanctioning bod-

ies shou ld be con sulted du ring the de sign p rocess.

DRAINAGE FACILITIESDitches & Gutter s

CurbsBerms

Slope Protection

Porous Pavements

EROSION CONTROLJetties & Groins

Grout for Jetties

Storm water management ponds

FARM

BarnyardsFeed lots

Stable Floors

Silage Storage

HYDRAULICSReservoir Linings

Pond Linings

Dam Faces

Canal Linin gs

Sewage Lagoons

Leach ate facilities

INDUSTRIAL-COMMERCIALDock Surfaces

Building Floors

Material Storage Areas

PATCHINGMaintenance For All Types of Pavements

RAILROADSHMA Ballast Un de rlaymen t

Full Dep th Hot Mix Asph alt

RECREATIONBoat Ramp s

Ath letic Fields

Skate b oard and roller blade facilities

Holding Areas

Helioports


19/20

Ad van ce d Asp halt Te ch no lo gie s, L.P. Ste rlin g, VA 703-4 44-420 0 703-44 4-4368

Alban Tractor Com p any, Inc. Baltimore, MD 410-686-7777 410-686-3729

Am erican Paving Fabrics, Inc. Hanover, MD 410-379-2209 410-796-0272Associated Asp halt Greensboro , NC 336-294-0025 336-297-3316

Astec, Inc . Ch attanooga,TN 423-867-4210 423-867-3570

Bitumar USA, Inc. Baltimore, MD 410-370-0360 410-757-1471

BP Lubrican ts USA, Inc. Baltimore, MD 800-777-1466 410-682-9485

Carroll Indep enden t Fuel Co. Baltimore, MD 410-235-1066 410-235-1941

C he sa p ea ke Fo rd & St e rlin g Tr u ck Sa le s Ba lt im o re ,M D 4 10 -6 8 2-4 00 0 4 1 0-3 91 -4 3 57

C on st e lla tio n N ew En e rg y-G as D iv is io n Ba lt im o re ,M D 4 10 -2 3 0-4 78 3 4 1 0-2 30 -4 6 79

CreaFill Fibers Corp oration Ch estertow n, MD 800-832-4662 410-810-0793

Financial Benefit Services Kensington , MD 301-949-1000 301-949-7038

Fleet Transit, Inc. Baltimore, MD 410-355-7910 410-355-2372

George Associates, Inc. Silver Sp ring, MD 301-589-9490 310-588-6605

Hi Tech Asp halt Solutions Mech an icsville ,VA 804-730-4871 804-730-7789

HMS In su ran ce Asso ciat es, I nc . Bro ok lan dville , MD 4 10 -3 37 -9 75 5 4 10 -3 37 -0 55 1

Humbolt Manufactu ring Co. Raleigh , NC 919-833-3190 919-833-5283

L&J Construction Service, Inc. Baltimore, MD 410-243-3844 410-243-2309

Luck Stone Corp oration Leesburg,VA 703-777-3177 703-779-4774Martin Marietta Aggregates Boonsboro, MD 301-739-0846 301-739-4718

Maryland Materials, Inc. North East, MD 410-287-8177 410-287-3654

Meeker Equip m ent Co., Inc. Lansdale, PA 215-361-2900 215-361-1725

E. Stew art Mitchell, Inc. Baltimore, MD 410-354-0600 410-354-3029

Nustar Energy LC West Dep tford, NJ 856-224-7200 856--224-7201

Patuxen t Materials, Inc. Crofton , MD 410-793-0181 410-793-0741

QPR a div. of Lafarge Ch ester, CT 800-388-4338 678-746-2238

Recon Construction Services, Inc. York, PA 717-779-0663 717-779-0724

Rifk in ,Liv in gs to n ,Le vit an & Silve r,LLC G re e n be lt ,M D 3 01 -3 4 5-7 70 0 3 0 1-3 45 -1 2 94

Roadtec, Inc. Ch attanooga,TN 423-265-0600 423-265-7521

Seaboard Asp halt Products Co. Baltimore, MD 410-355-0330 410-355-5864

Sie man s, WT-Hyd ro car bo n Se rvic es Alex an dr ia, VA 7 03 -3 70 -7 30 6 7 03 -3 70 -8 06 7

Stonetech , LLC Salisbury, MD 410-742-2851 410-749-7411

Valero Services Lafayette Hill, PA 888-207-3727 610-567-3291

Volvo Construction Equip ment Elkridge, MD 410-796-3200 410-796-3350

Vulcan Materials Comp any Manassas,VA 703-631-9690 703-368-2139York Building Products Co ., Inc . York, PA 717-848-2831 717-854-9156

ASSOCIATE MEMBERS

Company Location Phone No. Fax No.

HOT MIX ASPHALT

SAFE, SMO OT H, QUIET, D URABLE AND 1 0 0 % RECYCLABLE


20/20

MARYLAND ASP HALT A SSOCIATION, IN C.

24 0 8 -G Pep p er Mi l l Dr i ve

G len B u r n i e , M a r y l a n d 2 1 0 6 1

4 1 0 -7 6 1-2 1 6 0 Fax 4 1 0 -7 6 1-0 3 3 9

E-ma i l : off i ce@m d a sp ha lt .o r g

MARYLAND ASPHALT ASSOCIATION, INC.

PRODUCERS

Company Location Phone No. Fax No.

Aggre gate In du strie s Mid -Atlan tic Gre en be lt, MD 30 1-982-1 400 30 1-513 -0 016

American Infrastructure Malvern , PA 610-560-7913 610-560-7955

American Paving C orp oration Salisbury, MD 410-742-8484 410-742-0504

David A. Bram ble, Inc . Chester tow n, MD 410-778-3023 410-778-3427

Francis O. Day Com p any, Inc. Rockville , MD 301-652-2400 301-424-4443

Ed ge m oo r Ma te rials o f Mar ylan d , In c . N or th Ea st , MD 4 10 -2 87 -5 55 5 4 10 -2 87 -3 48 1

P. Flan igan & Sons, Inc. Baltim ore, MD 410-467-5900 410-467-3127

C.William Hetzer, Inc . Hagerstow n, MD 301-733-7300 301-733-0812

IA Construction Corp . Cum berland, MD 301-724-1760 301-724-0864

Keystone Lime Co . Sp rings, PA 814-662-2711 814-662-4421

Richard F. Kline, Inc. Frederick, MD 301-662-8211 301-662-2083

Lafarge North America Tow son , MD 410-847-3300 410-847-3308

Laurel Sand & Gravel, Inc. Laurel, MD 301-953-7650 301-470-4075

Maryland Paving, Inc. Aberdeen , MD 410-879-6970 410-879-5478

C J Miller, LLC Hamp stead, MD 410-239-8006 410-239-4204

Fo rt Mye r Co n st ru c tio n Co rp o rat io n Wash in gt on , D C 2 02 -6 36 -9 53 5 2 02 -6 35 -0 57 5

Pen nsy Sup ply In c./ Tilcon Delaw are Dover, DE 302-735-9950 302-678-3379

Re lia ble Co n tr ac tin g Co m p an y, I n c. Mille rsville , MD 4 10 -9 87 -0 31 3 4 10 -9 87 -8 02 0

River Asp halt, LLC Dover, DE 302-342-3137 302-342-3160

Valley Q uarries Chambersburg, PA 717-267-2244 717-267-2521

LW Wolfe En terp rises, Inc. Myersville , MD 301-293-2351 301-293-3578

Asp halt General Beltsville , MD 301-937-3900 301-937-3893

Asp halt & Co nc re te Se rvic es, In c. Fre de ric k, MD 301 -682-56 90 30 1-682 -5 695

Melvin Benhoff Sons, Inc. Baltim ore, MD 410-477-5650 410-477-5091

Central Main tenance Corp . Baltim ore, MD 410-355-8800 410-355-4847

College Park Paving Co., Inc. Beltsville , MD 301-937-1447 301-937-6971

Comer Construction Co. Forest Hill, MD 410-879-6094 410-638-0289

Dix ie Construction Co ., Inc . Churchville , MD 410-879-8055 410-836-2029

Fran k J.Go ett ne r Co nst ru ctio n Co ., In c. Kin gsville , MD 4 10 -5 92 -7 70 0 4 10 -5 92 -5 96 8

Gray & Son , Inc. Butler, MD 410-771-4311 410-771-8125

Iacoboni Site Sp ecialists Baltim ore, MD 410-686-2100 410-686-8559

Kinsley Construction , Inc. Timonium , MD 410-453-6707 410-453-6709

M.T. Laney Co., Inc. Eldersburg, MD 410-795-1761 410-795-9546

Pleasan ts Construction , Inc. Clarksburg, MD 301-428-0800 301-428-3922

Priceless Industries, Inc. Baltimore, MD 410-285-1900 410-282-8347

Quarry Ridge Asp halt Co. Cum berland, MD 301-777-8825 301-777-8274Ross Contracting, Inc. Mt.Airy, MD 301-831-5500 301-831-5900

CONTRACTORS

Avalon Consulting Services Baltim ore, MD 410-945-9553 410-945-9554

The Rober t B. Balter Com p any Ow ings Mills, MD 410-363-1555 410-363-8073

CNA, Inc. Forest Hill, MD 410-879-7200 410-838-1811

Co n st ellat io n D esig n Gr ou p , In c . Tim o niu m , MD 4 10 -2 52 -1 88 4 4 10 -5 60 -3 63 2

De ve lo p me nt Fac ilit at or s, I nc . Mille rsville , MD 4 43 -3 08 -2 10 0 4 43 -3 08 -2 10 8

EBA Engineering, Inc. Baltim ore, MD 410-358-7171 410-358-7213

Greenhorne & OMara, Inc. Baltim ore, MD 410-583-6700 410-583-6704

Greenman-Pedersen , Inc. Jessup , MD 410-880-3055 301-490-2649

Indam Engineers, Inc. Ellicott City, MD 410-461-0001 410-461-0006

Joh nson , Mirm iran & Thom p son Sp arks, MD 410-329-3100 410-472-2200

KCI Technologies, Inc. Hunt Valley, MD 410-316-7970 410-316-7972

PB Americas, Inc. Gaitherburg,MD 703-742-5833 703-742-5789

Progressive Engineering Consultants,Inc Columbia, MD 410-715-0390 410-715-1745

URS Corp oration Hunt Valley, MD 410-785-7220 410-785-6818

Rum mel, Klep p er & Kahl Baltim ore, MD 410-728-2900 410-728-2834

Sp ec ialized Engineering Hanover, MD 410-768-4800 410-768-4803

Wallace Mon tgom er y & Associates Tow son , MD 410-494-9093 410-825-5714

CONSULTING ENGINEERS

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