Roofing Waste In Asphalt Paving Mixtures paving mixtures can be produced which contain up to, twenty

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Text of Roofing Waste In Asphalt Paving Mixtures paving mixtures can be produced which contain up to, twenty

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I G. PAULSEN

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BY Greg Paulsen

Mary Strou-rdiner Jon Epps

Center for Construction Materials Research Department of Civil Engineering

University of Nevada Reno, Nevada 89557

(702) 784-6858

- G. PAULSEN

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T h i s paper addresses the technical f e a s i b i l i t y of u t i l i z i n g

roofing waste products i n asphalt concrete paving mixtures.

Approximately .nine million tons of roofing w a s t e are generated

annually: i n the 'United States. Disposal cos t s a r e s ignif icant .

Recycling represents an economical and, perhaps, environmentally

a t t r a c t i v e a l t e rna t ive t o placing these wastes i n l andf i l l s . The

r e l a t ive ly large quant i t ies of asphal t cement and "aggregate type"

materials present i n roofing waste suggest that it has the potential

a s a p a r t i a l subs t i tu te fo r asphalt cement and/or aggregate i n a

paving mixture.

A study was conducted which arrived a t the following conclusions:

1.

2.

3.

4.

5 .

6.

Acceptable paving mixtures can be produced which contain up

to, twenty percent by volume of zoofing waste:

Propr selection of binder type and quantity is critical t o

t h e performance of t h e mixture and depends on t h e type and

quantity of the roofing waste i n the mixture:

Improved asphalt cement ex t r ac t ion and recovery processes

need t o be developed t o effectively determine the properties

of the asphalt cement i n the roofing waste:

Theatotal "active binder" content, depending on the effec-

tiveness of the recycling agents, should be considered when

designing asphalt concrete mixtures:

The gradations of conventional aggregates and roofing w a s t e s

should be considered when designing paving mixtures: and

The long-term field performance of paving mixtures containing

roofing waste needs t o be established.

i

. G . PAULSEN

Page

I.U.ION ..................................................... 1 .......................................................... 1 TEST ...................................................... 3 MATER-TALS ........................................................ 5 TEST RESULTS - RXXING WASTES ................................... 6 TEST F!ESULTS - ASPHALT CDICRETF, MMTURES ......................... 9 EXDNXCC CDNSIDERATION ........................................... 14 CD.SION ....................................................... 14 nrmRE .................................................... 16 A. .................................................. 16

' . .

REFERENCES ....................................................... 17 LIST OF TABLES ................................................... 18 LIST OF F1.S .................................................. 22

G. PAULSEN PAGE 1

1 " R D U C T I O N

e million tons of roofirq waste are generat

a ea Statesa(1). Disposal costs , a s wi th large amounts of any waste type8 are significant. Recycling represents an

economical alternative t o placing these wastes in land f i l l s . &cy-

c l ing of roofing waste in to paving mater ia ls is a disposal a l terna-

t ive . Typical roofing waste products, such as 91- p r

ing, contain about th i r ty-s ix pe t asphal t cemenk,

twenty-two percent hard rock granules:' (minus KO. 1 0 t o plus No. 60

sieve size) , eight percent f i l l e r (minus No. 100 sieve size material) 8 and smaller amounts of coarse aggregate (approximately one inch i n

s i z e ) , ce l lu lose f i b e r felt , g l a s s fiber fe l t , asbestos f e l t , and

polyester f i l m s . The relatively large quantities of asphalt cement and

"aggregate type" mater ia ls present i n roofing waste suggest t h a t it

has the poten t ia l a s a p a r t i a l s u b s t i t u t e for asphalt cercent ar!d/or

aggregate in a paving mixture. This report mntains the results of a

preliminary investigation for es tabl ishing the f e a s i b i l i t y of

u t i l i z ing roofing waste products in asphalt concrete paving mixtures.

A wide variety of waste products and by-products, including old

pavement materials, waste glass, battery cases. polypropylene contain-

ers . old t i r e s , f l y ash, bottom ash, s lag , etc., can be successfully

incorporated into paving materials from a technical standpoint ( H I .

From a nat ional perspective and based on both a technical and an

economic viewpoint, the reuse of old pavement materials, old t i res ,

. G. PAULSEN PAGE 2

f l y ash, and slag have been successful. Literature is not available

which addresses t h e technical and economic f e a s i b i l i t y of using

roofing wastes in asphalt paving mter ia l s .

Several technical items w i l l have t o be addressed p r io r t o the

widespread use of roofing waste in asphalt concrete mixtures. These

item include:

1. The naturetad quantities of the materials in roofing waste

including the properties of t h e asphalt cement and the grain

size distribution of the solid material,

2. The quant i ty of roofing waste t h a t can be introduced. i n to a

paving mix t u re without adversely a l t e r ing the engineering

properties of the mixture,

3. The quantity and t y p of asphalt cement and/or aromatic type ,

G. PAULSEN PAGE 3

TEST PRDGRAM

Roofing wastes from five sources have been obtained and subjected

t o the test program shown in Figure 1. Samples of roofing waste were

obtained and processed t o one inch and one-quarter inch m a x i m u m size.

F&ofing wastes and their components were subjected t o the following

American Society for Testing and Materials (ASTM) tests. Gradations

(ASTM C136) and specific gravities (ASTM D2041) were obtained prior t o

the extraction ard recovery of the asphalt cement. After t he extrac-

t i o n and recovery of t h e asphalt cement, penetration (ASTM D5) and

v iscos i ty @SI% D2170, D2171) t e s t s were performed on the asphalt

cement. The gradations of the solids were determined. and photographs

were taken.

Asphalt Concrete Mixtures

Figures 2 and 3 a d Table 1 describe the asphalt concrete mixture

t e s t program. This portion of the study was performed in four parts

as described on Figure 2- A Marshall mixture design was performed on

the control materials t o establish binder contents fo r the selected

aggregate and aggregate gradation.

Two preliminary tes t programs were conductedi. The f i r s t prelim-

inary program u t i l i zed a roofing waste from Texas t o establish reason-

able ranges of t e s t variables t o u t i l i z e i n the study. The second

preliminary program involved the t e s t ing of f i v e roofing wastes t o \

establish t h e properties of the mixtures as affected by the type and

aniou.nt of added binder and by the source of t h e roofing waste. The

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na jo r portion of the mixture t e s t i n g program was performed on two

G'. PAULSEN PAGE 4

roofing wastes as shown on Table 1. The f i r s t th ree p a r t s of t h e

mixture t e s t ing program depicted on Figure 2 were performed t o

establish the source of roofing waste, range of quantities of roofing

waste, type of added binder, and quant i ty of added binder t o be used

i n t h e four th pa r t of t h e study. The t e s t ing sequence shown on

Figure 3 w a s utilized in a l l four parts of the mixture test program.

Asphalt concrete mixtures were subjected t o t h e test methods

Samples were mixed

Fif ty

shown in Figure 3 and are briefly described below.

and compacted according t o PSCM D1559 using 50 blows per side.

blows per s ide corresponds t o nediun! t r a f f i c conditions (2). Each

mixture was placed i n an oven a t t he specif ied 275' F compaction

temprature for one and a half hours after t h e completion of m i x i n g .

This was done t o simulate the mixing a t the hot plant, transportation

t o the job si te. and laydown elapse time. i n addition, t h i s ex t r a

time would allow the recycling agent t o digest the aged roofing waste

asphalt cement. Each mixture was then remixed prior t o ccmpaction.

B u l k spec i f ic g r a v i t i e s were obtained using P-STM D2726. The

r e s i l i e n t modulus (Young's modulus fo r v i scoe la s t i c mater ia ls) was

determined by ASTM D4123. The load w a s applied for a duration of 0.1

seconds; the load cycled a t threesecond intervals- Indirect tensi le

strength was determir?& according t o ASTM D4123 using a loading rate

of two inches per minu te and a d ry sample a t 77' F- Hveem s t a b i l i t y

was determined according t o ASTM D1560. Marshall s tab i l i ty and flow

were determined according t o ASTM D1559. Rice specific gravities were

deterrriined according t o A s h 1 D2041- A cor