U.S. patent application number 13/887828 was filed with the patent office on 2014-05-29 for microwave processing unit for pavement recycling and asphalt pavement production.
This patent application is currently assigned to Leap Technologies, Inc.. The applicant listed for this patent is Leap Technologies, Inc.. Invention is credited to Mark ELIOT.
Application Number | 20140146632 13/887828 |
Document ID | / |
Family ID | 49514941 |
Filed Date | 2014-05-29 |
United States Patent
Application |
20140146632 |
Kind Code |
A1 |
ELIOT; Mark |
May 29, 2014 |
MICROWAVE PROCESSING UNIT FOR PAVEMENT RECYCLING AND ASPHALT
PAVEMENT PRODUCTION
Abstract
An asphalt plant for producing a high performance hot mix
asphalt product, comprising: RAP material, emulsion added to the
RAP, and low energy microwave heating system for processing the RAP
emulsion mix.
Inventors: |
ELIOT; Mark; (Minnetonka,
MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Leap Technologies, Inc.; |
|
|
US |
|
|
Assignee: |
Leap Technologies, Inc.
Minnetonka
MN
|
Family ID: |
49514941 |
Appl. No.: |
13/887828 |
Filed: |
May 6, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61643010 |
May 4, 2012 |
|
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61643046 |
May 4, 2012 |
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Current U.S.
Class: |
366/24 |
Current CPC
Class: |
E01C 19/05 20130101;
Y02A 30/30 20180101; E01C 19/1045 20130101; Y02A 30/333 20180101;
E01C 19/1036 20130101; E01C 19/1004 20130101; E01C 19/1013
20130101 |
Class at
Publication: |
366/24 |
International
Class: |
E01C 19/10 20060101
E01C019/10 |
Claims
1. An asphalt plant for producing a high performance hot mix
asphalt product, comprising: RAP material; emulsion added to the
RAP; low energy microwave heating system for processing the RAP
emulsion mix.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to and incorporates
by reference the following U.S. Provisional Patent Application Nos.
61/643,010 and 61/643,046 filed on May 4, 2012, and is a
continuation in part of and incorporates by reference U.S. patent
application Ser. No. ______ filed on May 6, 2013.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention is in the technical field of asphalt
production. More particularly, the present invention relates to the
use of microwave energy in the production of asphalt products.
[0004] 2. Background
[0005] Prior art asphalt production plants have remained virtually
unchanged for decades (see FIG. 1). Asphalt cement and aggregate
are combined in a mixing facility where they are heated,
proportioned, and mixed to produce the desired paving mixture.
Hot-mix asphalt ("HMA") facilities may be permanently located (also
called "stationary" facilities), or it may be portable and moved
from job to job. Hot-mix facilities may be classified as either a
batch facility or a drum-mix facility; both can be either
stationary or portable. Batch-type hot-mixing facilities use
different size fractions of hot aggregate which are drawn in
proportional amounts from storage bins to make up one batch for
mixing. The combination of aggregates is dumped into a mixing
chamber called a pugmill. The hot liquid asphalt, which has also
been weighed, is then thoroughly mixed with the aggregate in the
pugmill. After mixing, the material it is then emptied from the
pugmill into trucks, storage silos, or surge bins. The drum-mixing
process heats and blends the aggregates with asphalt all at the
same time in the drum mixer. Typically $500-$700 or more of natural
fuels are burned for every hour of production. When mixing is
complete, the hot-mix is then transported to the paving site and
spread with a paving machine in a partially compacted layer to a
uniform and even surface layer. While still hot, the paving mixture
is further compacted by heavy rolling machines to produce a smooth
pavement surface.
[0006] Heat used in the production of hot-mix asphalt is one of the
main targets in efforts to reduce the energy profile and
environmental impact of such facilities. Prior art facilities
consume large amounts of energy and produce substantial amounts of
pollutants. In recent years the development of WMA or warm mix
asphalt was developed as a solution, but this solution suffers from
a number of drawbacks. While hot-mix asphalt is produced at 350 to
400 degrees, WMA is produced at 300 degrees, which still requires
enormous energy and produces only incrementally less pollutants.
While these mixes show slight promise more information is needed to
draw definitive conclusions regarding their effectiveness and
performance as pavemet, but WMA does not does not fundamentally
solve the underlying problems associated with asphalt
production.
[0007] Another problem with current asphalt production, especially
with hot-mix asphalt, is it is produced using very little recycled
pavement material ("RAP"). As RAP is harvested from roadways or
parking lots only a small amount will be used in new HMA
production. Current nationwide standards show new HMA to contain
anywhere from 20% to 35% of RAP in the HMA mix design. In most
cases higher amounts of RAP causes a decline in new HMA
performance. As the years go by RAP piles continue to grow faster
than material can be utilized in HMA. In several regions RAP is
used as base material for roadways.
[0008] Thus, a need exists for an improved asphalt product and
method of producing asphalt that does not suffer from the drawbacks
and disadvantages of the prior art.
SUMMARY OF THE INVENTION
[0009] An object of the present invention is to provide an improved
apparatus and method for an asphalt plant for producing a high
performance hot mix asphalt product, comprising, RAP material,
emulsion added to the RAP, and low energy microwave heating system
for processing the RAP emulsion mix. These and other objects of the
present invention will become apparent to those skilled in the art
upon reference to the following specification, drawings, and
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a drawing of a prior art asphalt plant.
[0011] FIG. 2 is a depiction of the steps of a process of producing
high performance hot mix asphalt ("HMA") in accordance with the
present invention. The drawing on the left depicts recycled asphalt
pavement ("RAP") material (up to 100%) from roadways or parking
lots; the drawing in the center depicts a sized and injected
engineered emulsion, which can constitute about 5% of the product;
and the drawing on the right depicts a fused high performance
HMA.
[0012] FIG. 3 is a block flow diagram of LEAP Process.
[0013] FIG. 4 is a drawing of a portion of a microwave heating
system used in accordance with the present invention.
[0014] FIG. 5 is a floor plan.
[0015] FIG. 6 is a floor plan.
[0016] FIG. 7 is a rendering of a LEAP plant.
[0017] FIG. 8 is a floor plan.
[0018] FIG. 9 is a graph of LEAP Rut Test Results.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The present invention comprises a plant for producing a low
energy asphalt pavement, which utilizes tested and designed
equipment having a low energy heating system using microwave
technology and manufacturing process ("LEHS") for using up to 100%
recycled asphalt pavement ("RAP") to convert it into high
performance hot mix asphalt ("HMA") that out performs prior art
asphalt products of any type. LEHS uses very little energy and
generates virtually untraceable amounts of pollution when compared
to current existing methods of producing HMA.
[0020] In general the process comprises the steps shown in FIG.
2.
[0021] The process starts with RAP material recovered from
roadways, parking lots or other paved surfaces. The process can use
varying amounts of RAP including up to 100% RAP, which allows for
maximum reuse or recycling of product. An emulsion is added to the
product, as describe in more detail below, the emulsion can
constitute about 5% of the product (or variations therefrom). After
processing as described below, a fused high performance HMA product
is produced.
[0022] The RAP raw used for production, and tested as described
below, came from several different climatic zones of the United
States and represented the multiple variations of pavement that are
present in the field. The injection process can use conventionally
available engineered asphalt emulsions at a rate of 4% to 8%. The
finished material has strength characteristic twice that of the
best HMA currently in production, and at least as much flexibility
to resist cracking as with prior art HMA.
[0023] The production process utilizes a much smaller footprint
than existing pavement HMA manufacturing plants. The production
process utilizes substantially less energy, reduces the processing
temperatures, and produces substantially less pollution, and unlike
prior art asphalt production facilities these advantages allow the
production facility to be placed inside an enclosed building
opening up better strategic plant placement reducing trucking
making the process and product more economical. The facility,
without the prior art environmental and other problems, can be
located closer to the points of use of the product, which tend to
be in densely populated areas that previously would not be suitable
locations for an asphalt plant. Also, an enclosed plant can operate
in cold and inclement weather, which is not possible or practical
for outdoor facilities. In colder climates, the energy demands
needed to heat the product and the use of open flames made it
impossible to operate indoors and extremely expensive to operate in
cold weather; so much so that asphalt plants in colder climates
close during the winter. The present invention substantially
eliminates these and other problems.
[0024] FIG. 3 describes the general flow of the process of
producing HMA in accord with the present invention. The steps
thereof are described herein below. The low energy asphalt
production ("LEAP") process of the present invention process
involves RAP receiving, RAP sizing and engineered emulsion
injection, ambient temperature I-RAP (RAP injected with emulsion)
storage, processing through the low energy microwave heating system
("LEHS"), and storage and shipping of the final HMA product.
[0025] The LEAP standard HMA mix design is based on weight, and is
to utilize about between 4 to 8 percent emulsion, about between 96
to 92 percent RAP, and optional addition about 1 percent lime,
corresponding to an 85 tons per hour ("TPH") RAP feed rate, 4.5 TPH
of emulsion, and 0.9 TPH of lime. Incoming RAP can be stored inside
or outside the facility. Storing inside prior to processing will
reduce moisture content on the feedstock from approximately 4 to 7
percent moisture at the time of delivery to minimum quantities at
the time of use. Excess water, if any, is driven off within the
microwave heating section and does not impact the final product
quality.
[0026] RAP Receiving
[0027] LEAP receives RAP via end dump trucks through a truck sized
garage door opening in the side of the processing building; the
incoming material is moved with a front end loader, conveyor or
similar device. RAP is piled in a corner of the building forming
multiple connected piles designed preferably for combined storage
of approximately 20,000 tons of material. Incoming RAP is to be
graded by source. LEAP intends to utilize RAP from highways or
other public projects to the extent practical to limit the amount
of incoming aggregate that is outside typical HMA DOT
specifications. Should it become necessary to utilize RAP from
multiple sources, LEAP intends to from multiple piles to facilitate
multiple mix designs.
[0028] RAP Grinding and Emulsion Blending
[0029] RAP is to be ground using nominal 250TPH throughput grinding
and blending unit, which are commercially available from Nesbitt
Contracting or Caterpillar Corporation, which is designed to size
RAP to between one and a-quarter inch and one-half inch size
depending on final mix design. The crushing/injection unit includes
a screen on the incoming RAP that allows material of one and one
half inch or less in size to enter the grinding section. Oversized
material that will not pass through the incoming screen is sent to
a crushing section to be reduced in size and then returned to the
incoming screen. Water is added to the RAP prior to grinding to
control dust and minimize heat generation within the grinding
machine. Output from the grinding section is sent to two parallel
pug mills, which have the ability to blend or inject up to two
different grades of the liquid engineered emulsion with the ground
RAP. Solid and liquid material is blended within a pug mill using
the opposing paddles on two parallel shafts; the paddles
simultaneously mix the material and push the mixture from the inlet
to the outlet of the mill. The RAP-emulsion blend, known as
intermediate or injected RAP ("I-RAP"), is to be conveyed from the
outlet and piled on either side of the crushing/injection unit,
production is sized such that the I-RAP material can be produced at
approximately 3 times the rate of the heating process (described
below). I-RAP can be stored at ambient temperature for up to 8
weeks prior to processing into HMA.
[0030] Low Energy Heating System (LEHS)
[0031] LEAP utilizes a microwave heating system (shown in FIG. 4)
to heat the I-RAP to a pre-specified temperature prior to delivery
for silo storage and/or to paving contractors. This system, known
by LEAP as the Low Energy Heating System ("LEHS"), uses microwave
energy of about 915 MHz to selectively heat the aggregate within
the I-RAP, enabling LEAP to heat the mixture without degrading the
asphalt cement within the emulsion. LEAP uses two parallel heating
systems with a minimum of about 300 kW to 800 kW, each with 45 to
75 TPH of capacity, to process the I-RAP. Each LEHS system includes
a minimum of four microwave transmitter units with a splitter/wave
guide that directs microwave energy from each transmitter into two
rotary head heating chambers, resulting in a combined eight
chambers per system (16 heating chambers per facility). I-RAP is
passed through the microwave heating chambers using a belt conveyor
at an I-RAP depth of slightly greater than 3 inches.
[0032] The engineered emulsions designed for use with the LEHS are
preferably capable of insulating and protecting the remaining
asphalt binder present in the RAP from the violent heating power of
the microwaves. In particular, aged RAP normally has 2.4 to 4%
asphaltene binder, asphaltines are present in asphalt and the ratio
of desirable maltenes to asphaltenes decreases over time due to
weathering and oxidation causing the asphalt to become dry or
brittle. High concentration of asphaltene has heretofore limited
the usefulness of RAP such that it either cannot be used, can only
be used in limited quantities resulting on an inferior dry brittle
product, or the asphaltines can be burned off at temperature
producing pollutants. LEAP can utilize up to 100% RAP because it
can rejuvenate asphaltenes, or otherwise increase the ration of
maltenes to asphaltenes resulting in a very high quality HMA
product. The microwave transmitters have the ability to generate
variable or constant power and the degree of heating is to be
controlled by LEAP by adjusting the power and conveyor belt speed
to increase or reduce the exposure time of the I-RAP within the
LEHS. By varying the intensity of the power within the chamber or
series of chambers different HMA mix designs can be produced with
different performance characteristics.
[0033] Various exemplary layouts for the LEAS/LEAP plant are shown
in FIGS. 5-8, and can accommodate up to two LEHS systems can be
located in close proximity within a plant.
[0034] LEAP HMA Performance Characteristics
[0035] LEAP HMA for has been tested in comparison to Superior
Performing Asphalt Pavements ("Superpave") standard developed for
the U.S. Department of Transposition, Federal Highway Commission
and used for all paving projects that are funded in a whole or in
part by federal funds. The principal measurement used for the
evaluation of HMA is the tensile strength ratio ("TSR") which is
used to predict the durability of the HMA. Some southern states,
notably Texas and Louisiana, have replaced the TSR measurement with
the Hamburg Rut Test measurement as HMA laid at elevated
temperatures can become brittle. The following table shows the
results of testing performed on LEAP HMA against the foregoing
standards.
TABLE-US-00001 LEAP HMA Property Testing Results per AET, Jan. 12,
2013.sup.(1) (HMA Samples from Dec. 20, 2012 and Jan. 9, 2013) LEAP
at LEAP at LEAP at Superpave HMA 230.degree. F. 220.degree. F.
290.degree. F. Property SPWEB340B.sup.(2) No Lime With Lime With
Lime Asphalt Cement or Emulsion 5.5 5.0 5.0 5.0 Content - % by
weight TSR 80.9 73.8 75.5 83.4 Percent Air Voids 4.0 3.0 2.8 3.8
Hamburg Rut Test - 12.5 8,500 N/a 19,000 20,000+.sup.(3) millimeter
depths Bulk Specific Gravity 2.438 2.356 2.358 2.356 Density,
lb./ft.sup.3(4) 152.1 147.0 147.1 147.0 Maximum Specific Gravity
2.540 2.396 2.422 2.396 Dry Tensile Strength, psi.sup.(5) 68.1
128.6 199.1 226.3 Soaked Tensile Strength, psi 55.1 94.9 150.3
188.8 .sup.(1)Engineering Testing Summary, Crius Corporation
Asphalt Plant Air Emissions Engineering Test, Dec. 18, 2012, AET
Project Number 14-01235 .sup.(2)SPWEB340B is a Minnesota Department
of Transportation Superpave specification where "SP" indicates the
gyratory (testing) design, "WE" indicates a wear mixture, "B"
indicates <3/4'' aggregate, "3" indicates the traffic level,
"40" indicates 4.0 percent design air void, and the "B" indicates
the virgin asphalt cement binder grade. .sup.(3)Test halted at
20,000 cycles, the upper limit of the testable range.
.sup.(4)Lb./ft.sup.3 = pounds per cubic foot .sup.(5)Psi = pounds
per square inch.
[0036] The Superpave specification, and most derivative state
specifications, do not permit the use of more than 25 to 50 percent
RAP within the HMA mix design due to the inability of traditional
batch and drum HMA plants to sufficiently heat the aggregate within
the RAP to temperatures necessary to meet the minimum TSR
specifications without forming excess smoke emissions and
particulate matter which violates standard air permits. The HMA
produced using LEAP production process meets or exceeds the min TSR
specification for most states while using 100% RAP and produces
virtually zero emissions or particulate matter.
TABLE-US-00002 Minimum TSR for Select State DOT Specifications TSR
(Minimum) States 85% MS (with 1% lime) 80% VA, OR, FL, AL, NM, OK,
SD, IA, NY, GA, AR, MN 70% CA, NV, MO, CO 60% AZ Hamburg Rut Test
TX, LA, UT
[0037] Several of the southern states have moved to the Hamburg Rut
Test for a more robust measurement of durability of the HMA. Virgin
asphalt cement had two primary chemical components, asphaltenes and
maltenes. Asphaltenes are hard materials that provide the
mechanical strength while maltenes are the oily fraction which
functions as the sticky component in HMA. Maltenes oxidize with age
or excess heat to form asphaltenes which causes the HMA to become
hard and brittle. The aged or heat damaged HMA cracks under heavy
loads causing failures of the road surface. The Hamburg Rut Test is
performed using a wheel which passed over an HMA sample until the
ensuing rut exceeds 12.5 millimeters in depth. Southern states,
where summer paving temperatures can prematurely age the HMA, have
been transitioning to the Hamburg Rut Test as a proxy measurement
to ensure that the maltene fraction was not damaged during
application. This test is an important benchmark for LEAP HMA as
the asphalt cement within RAP has been aged, and traditional HMA
using RAP is excess of 25 percent had a proclivity to fail early
due to the relative lack of maltenes.
[0038] The graph in FIG. 9 shows the results for testing of two
variations of the LEAP HMA.
[0039] LEAP Rut Test results far surpass Rut Test results for the
best performing HMA product s, especially when you consider the RAP
used was never designed for loading anywhere near this level
(tensile <60).
[0040] The Green line represents material that was heated to 220
degrees; the purple line was heated to 290 degrees. Conventional
Superpave HMA fails at 8500 passes, while the LEAP HMA exceeded
20,000 cycles in some cases without failure.
[0041] LEAP Emissions
[0042] Emission testing shown below was performed for particulate
and volatile organic carbon ("VOC") testing of the exhaust from an
indoor LEHS system inside. The summary of which is included below.
[0043] Overview: Particulate and VOC air emission testing was
conducted on a pilot scale asphalt plant on Dec. 18, 2012.
Particulate emission testing was conducted according to EPA Method
5 and EPA Method 202. VOC emission testing was conducted in
adherence with EPA Method 25A using a Total Hydrocarbon (THC)
Analyzer. At the time of the emission test, the pilot scale asphalt
plant was producing 10 Tons/Hour of asphalt. [0044] A federal
regulation (NSPS Subpart 1) exists for particulate matter for all
Hot Mix Asphalt Plants (HMA). Currently, there is not a federal
regulatory limit for VOC; VOC emissions are compared to the EPA
emission factors in the table below. Detailed test results can be
found in Table 1 and Table 2 which are attached to this
document.
TABLE-US-00003 [0044] Emission Unit Tested Pollutant Test Result
Federal Standard Cirus Pilot Scale Particulate .ltoreq.0.04 0.0006
Asphalt Plant as Matter Grains/DSCF Grains/DSCF Tested Cirus
Asphalt Plant Particulate .ltoreq.0.04 0.005 (Scaled up 8 times)
Matter Grains/DSCF Grains/DSCF EPA Emission Factor Cirus Pilot
Scale VOC 0.440 0.026 Asphalt Plant as Lbs/Hr .sup.a, b Lbs/Hr
.sup.a Tested .sup.a VOC is equivalent to the Total Hydrocarbons as
Propane. .sup.b This number represents the EPA emission factor for
VOC emissions for a Drum Mix HMA running on natural gas.
TABLE-US-00004 TABLE 1 Summary of Asphalt Plant Particulate Test
Results Crius Corporation -- Plymouth, Minnesota AET #14-01235
Parameter Run #1 Run #2 Run #3 Average Particulate Matter (PM)
Results Date Dec. 18, 2012 Dec. 18, 2012 Dec. 18, 2012 Run Time
9:28-10:28 11:43-12:42 13:28-14:28 Stack Temperature, .degree. F.
62 71 70 68 Stack Oxygen, % 20.7 20.7 20.7 20.7 Stack Carbon
Dioxide, % 0.2 0.2 0.2 0.2 Moisture, % 2.3 3.0 2.1 2.5 Stack Flow
Rate, DSCFM 700 700 700 700 Isokinetic Variation, % 101.4 100.1
99.2 100.2 Filterable Particulate Emission Results Particulate
Concentration, grains/dscf: 0.0010 0.0004 0.0005 0.0006 Particulate
Mass Rate, Lbs/Hr: 0.0059 0.0025 0.0028 0.0037 Organic Condensibles
Emission Results Particulate Concentration, grains/dscf: 0.0002
0.0003 0.0002 0.0002 Particulate Mass Rate, Lbs/Hr: 0.0011 0.0016
0.0013 0.0013 Inorganic Condensibles Emission Results Particulate
Concentration, grains/dscf: 0.0008 0.0008 0.0007 0.0008 Particulate
Mass Rate, Lbs/Hr: 0.0050 0.0046 0.0042 0.0046 Filterable + Organic
Condensibles Emission Results Particulate Concentration,
grains/dscf: 0.0012 0.0007 0.0007 0.0008 Particulate Mass Rate,
Lbs/Hr: 0.0070 0.0041 0.0040 0.0050 Total Particulate Emission
Results Particulate Concentration, grains/dscf: 0.0020 0.0014
0.0014 0.0016 Particulate Mass Rate, Lbs/Hr: 0.0119 0.0086 0.0082
0.0096
TABLE-US-00005 TABLE 2 Summary of Asphalt Plant VOC Emission Test
Results Crius Corporation - Plymouth, Minnesota Dec. 18, 2012 - AET
#14-01235 Airflow PPMv, Lbs/ PPMv, Lbs/ Exhaust Rate Ave As Hr As
Ave As Hr As Location SCFM Propane Propane Carbon Carbon Run #1
9:29-10:28 Asphalt Plant 700 5.90 0.028 17.7 0.023 Oven Outlet Run
#2 11:42-12:41 Asphalt Plant 700 4.94 0.024 14.8 0.019 Oven Outlet
Run #3 13:28-14:27 Asphalt Plant 700 5.10 0.025 15.3 0.020 Oven
Outlet AVERAGES RUNS # 1-3 Asphalt Plant 700 5.31 0.026 15.9 0.021
Oven Outlet
[0045] The pollution testing results indicate the LEAP plant will
fall well below the required emission standards for HMA production.
These results demonstrate that the LEAP plants are suitable for
locations that are outside the reach of conventional HMA plants in
most states due to pollution and air quality regulations.
[0046] LEAP Technologies plants can be placed in almost any
industrial zoning that supports trucking traffic. This
significantly increases the competitive advantage over conventional
asphalt plants by going where they cannot. Heretofore HMA plants,
due to pollution and emission issues, had to be located remotely,
and typically not near locations where the HMA product is used.
This greatly increased cost associated with product use because the
product has to be transported greater distances than in possible
with LEAP plants.
[0047] Furthermore, because LEAP plants can be located indoors and
have much reduced energy needs they can be operated year round in
colder climates and at much lower operating costs. Strategic
locations will reduce hauling rates and improve the economic impact
to the end users.
[0048] Still further, LEAP plants have a much smaller footprint
than conventional asphalt plants, providing even greater
advantages.
[0049] LEAP plants can be operated at the same time or operated
based on product demand. Unlike existing conventional HMA plants
there is little effort to engage production, simply turn on a few
switches and your production ready. The ease of production
engagement allows ability to have material readily available 12
months a year, even in northern climates. Existing HMA plants in
the northern regions are required to shut down during the winter
months due to the high operational costs and required placement
outdoors.
[0050] In the southern states or warmer climates the configurations
shown below allows for the RAP to be stored outside. LEAP plants
can be located within a city in a facility of 40,000 sq. ft. or
larger. By bringing the entire production process inside you retain
the ability to produce anytime without the high cold weather
start-up costs associated with conventional HMA plants.
[0051] While the foregoing written description of the invention
enables one of ordinary skill to make and use what is considered
presently to be the best mode thereof, those of ordinary skill will
understand and appreciate the existence of variations,
combinations, and equivalents of the specific embodiment, method,
and examples herein. The invention should therefore not be limited
by the above described embodiment, method, and examples, but by all
embodiments and methods within the scope and spirit of the
invention. For example, the LEAS system could be used to modify
existing asphalt plants to allow them to either reduce the level of
pollution, by reducing the heat necessary, and/or to increase the
amount of RAP used in the creation of HMA to perhaps as high as
about 70% to 80%.
* * * * *