ASTE C a division of Asiec Industries. tnc.

PO BOX 72787 4101 JEROME AVE. CHATTANOOGA, TN 37407 423-867-4210 FAX 423-867-463a nnr nr ,,.I 1 n

CONTENTS INTRODUCTION .................................................................................... 3 HOT MIX ASPHALT WITH ROOFING SHINGLES ............................... 4 SHREDDING AND INTRODUCTION INTO THE PLANTS ................... 5 ECONOMICS ......................................................................................... 8

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INTRODUCTION There are 77 plants in the United States producing roofing shingles. These 77 plants produce approximately 90,000,000 shingle squares per year, weighing in excess of 9,500,000 tons. Approximately 65% of the shingles are used for restoring roofs on houses and 35% on roofs for new houses. For each roof that is restored, the equivalent amount of old shingles are removed and must be discarded. In addition to this, each roofing plant in the United States generates asphalt factory scrap materials and seconds that can range from 5% to 10% of their production. The tabs or cutouts equate to 1% by weight.

Tabs from the roofing shingles have multiple uses and do not present a disposal problem. However, the seconds and the factory scrap from the operations pose a very difficult problem for the shingle manufacturer. Some plants are being forced to haul the scrap materiel as far as 300 miles away, costing as much as $60 per ton for disposal of their product. Landfills across the country are charging a minimum of $1 8 per ton and as high as $1 00 per ton to accept roofing shingles.

From the above, it is apparant that the largest volumn of shingles is in the tear-offs. These also are subject to the most contamination and require a more complex system to separate the nails, paper, etc., from the product.

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Asphalt

Filler

Granules

Felt

cut-out

TOTALS

68

58

75

0

22

2

225

30 38 19 72.5 31

26 83 40 58 25

33 79 38 75 32

0 4 2 0 0

10 0 0 27.5 12

1 2 1 0 0

206 235

Fiaure 1

Asphalt Q 120.001ton 30 Filler 0 7.001ton 26 Granular @ 7.001ton 33 Mat @ 7.00 /ton 0 Felt Q 7.001ton 10 cut-out 1

36.00 1.82 2.31

.7

19 40 33 2 1 1

22.80 2.80 2.66 .14 .07

31 25 32 0 12 1

37.20 1.75 2.24

.84

Sub-totals 40.83 28.47 42.03 Disposed cost 25.00 25.00 25.00

Sub-totals 65.83 53.47 67.03 Process cost (1 0.00) (10.00) (12.00)

8 4 percent $2.23 per ton $1.74 per ton $2.20 per ton .!! 5 percent $2.79 per ton $2.17 per ton $2.75 per ton 0 6 percent $3.35 per ton $2.61 per ton $3.30 per ton

Fiaure 2

HOT MIX ASPHALT WITH ROOFING SHINGLES The composition of roofing -

(organic or fiber glass). Figure 1

shingles basically vary depending on the type of of base material

shows the composition per roof- ing square of two different types of shingles being produced today, along with the shingles listed as “old.”

Figure 2 shows the net realized value of the shingles based on;

asphalt cost of $120 per ton, aggregate cost of $7 per ton disposal cost of $25 per ton processing cost of $10 for fresh, factory roofing scraps

old, tear-off roofing, $12 per ton

Figure 3 shows a typical mix de- sign utilizing 6% liquid asphalt.

Figure 4 shows the same mix design with the injection of 5% fiberglass base roofing shingle. Figure 5 shows the same mix design using 5% organic base shingles. Little changes in the mix property occur, as can be seen from these tables. Of course, each mixspecification would need to be evaluated to determine the effect of roofing as a mix component. Actual liquid asphalt savings will depend on the optimal results from mix design testing.

operation in Orlando, Florida, have shown that the use of 4-1 0% roof- ing shingles can increase the per- formance of the mix considerably. Parking lots at Disney World where

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Experiments, conducted at a plant -

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Figure3

10% of asphalt fiber glass-shingle were used have successfully dem- onstrated excellent performance over 8 years. High traffic of heavy trucks on entrance roads of an asphalt plant in Orlando have shown the mix made with fiber glass shingles to demonstrate much betterperformance than nor- mal asphalt mixes due to the addi- tional strength added by the fiber glass.

SHREDDING AND INTRODUCTION INTO THE PLANTS As a result of approximately five years of research by the Astec Division of Astec Industries, Inc., it has been determined that the shingles need to be shredded to at least 1/2 inch or smaller prior to introduction to the mix. The small size is necessary to insure proper melting of the shingles and uni- form introduction into the asphalt mix.

100.0 99.0 96.0 57.0 39.0 24.0 14.0 9.0 6.0 4.2

Added Total 5.1 6.0

Figure 4

Astecfirst utilized a modified wood hog to process the shingles. One of the major problems was in the handling and separation of the stacks of shingles. While the woodhog worked successfully, the mainte- nance of the machine was much higher than acceptable.

A second system was developed utilizing a slow speed shredder, similar to that used for automobile tires, plus a second stage hammer mill. Again this worked successfully in shredding the product but the maintenance was excessively high. The roofing granules used in the shingle process come from some of the hardest aggregate in the United States. The hardness seems to come with the opaqueness to light. While these granules are somewhat loosely attached with the asphalt cement to the backing material and the shredding process is conceptually only necessary to shred the backing of the material, the granular material leads to excessively high wear.

Figure 5

Fiaure 6 asphalt plants while reducing the total cost per plant.

Figure 6 shows the latest system developed by the Telsmith and Astec subsidiaries of Astec Indus- tries. A basic flow chart of this system is shown in Figure 7. This system consists of a primary feeder with a knuckle boom crane, (not shown). The knuckle boom crane is used to spread the shingles out so that a uniform feed can be obtained before feeding into a large horizontal shaft impactor which is the primary crusher. The primary crusher shreds the shingles down to approximately 2 inches. As thev are conveved UD a Fiaure 7

Figure 8

pass through. The oversized ma- terial drops from the screen onto a belt conveyor that leads to a sec- ondary horizontal shaft impactor. This machine is designed with special breakers and oper- ates at a higher speed, leading to a reduction of the product to less than 1/2” diameter. The material discharged from this secondary impactor drops onto the belt and back to the screening unit.

The material discharged from the screening unit is then fed to a conveyor leading to a surge hop- per. The surge hopper is automati- cally controlled by a blending sys- tem where the shredded shingles are conveyed to a pugmill and mixed with either sand or screen- ings (depending on the local mate- rial used as fine aggregate in the local asphalt mixes) and then fed to a radial stacker for stockpiling. Approximately 20% sand or screenings is necessary to pre- vent new shingles from sticking together again. Older shingles can often use less carrier material than this, but the amount varies with the temperature, hardness, etc.

The blended screenings and roof-

Figure 9

ing shingles can then be transported to multiple asphalt plants. The blended material can be fed to a batch plant as normal RAP as shown in Figure 8; to parallel flow drum mixers as shown in Figure 9; or to a Double Barrel@ plant as shown in Figure IO. When processing recycled asphalt, the same system can be used but the blending with carrier material is unnecessary. As shown in Figure 6 the pugmill and mixing device can be bypassed. Since the majority of available roofing shingles will be tear-offs with various contaminants, an eddy- current magnet can be installed prior to the screen to throw out aluminum flashing which often occurs as a contaminant in the product. An eddy- current magnet, however, adds substantially to the cost of the system.

Fiaure 10

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ECONOMICS Figure 2 shows the value of the roofing shingles based on $120 per ton liquid asphalt, $7 per ton aggregate, $25 per ton disposal fee and $1 0-$12 per ton processing cost. It also shows the economics of introducing various

asphalt mix. As can be seen, the economic benefits are very attractive. By introducing 5% organic shingles, the hot mix asphalt cost can be reduced

Considering the used shingles removed from roofs, plus the additional asphaltic wastes from the plants, there are nearly 7,000,000 tons of recyclable roofing material available each year. This equates to about 2,000,000 tons of liquid asphalt annually. This could supply approximately 20% of the liquid asphalt needed in all the asphalt mix produced in the United States each year. This would also be a sufficient quantity of shingles to add 1.4% into every ton of mix, reducing the cost by $.77 per ton. Considering the value of the old shingles as shown in Figure 2, a disposal cost of $25 per ton and a processing cost of $12 per ton, approximately $385,000,000 could be saved by the hot mix asphalt industry each year if all the recyclable roofing shingle in the United States were used. Based on $25 per ton for mixing, trucking and placing the liquid asphalt, 13,524,000 additional tons of hot mixcould be available for resurfacing our road system in the United States, while 7,000,000 less tons of material would be placed in our landfills.

As can be seen from the data above, roofing shingles in hot mix asphalt create an excellent opportunity for the hot mix industry to reduce cost while eliminating a major environmental problem.

percentages of fiberglass, organic and old shingles back into the hot

by $2.79 per ton. -

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