Canadian Journal of Civil Engineering
Life Cycle Assessment of Asphalt Pavement Maintenance and Rehabilitation Techniques: A Study for the City of St. John’s
Journal: Canadian Journal of Civil Engineering
Manuscript ID cjce-2019-0540.R1
Manuscript Type: Article
Date Submitted by the 09-Nov-2019 Author:
Complete List of Authors: Alam, Md Rakibul; Memorial University of Newfoundland, Civil Engineering Hossain, Kamal; Memorial University of Newfoundland, Civil Engineering Butt, Ali Azhar;Draft University of California Davis, Civil and Environmental Engineering Caudle, Tim; Memorial University of Newfoundland, Civil Engineering Bazan, Carlos; Memorial University of Newfoundland, Civil Engineering
Life Cycle Assessment (LCA), Pavement Maintenance & Rehabilitation, Keyword: Environmental Impacts, Global Warming Potential, Pavement Maintenance Activities
Is the invited manuscript for consideration in a Special Not applicable (regular submission) Issue? :
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Life Cycle Assessment of Asphalt Pavement Maintenance and Rehabilitation Techniques: A Study for the City of St. John’s
Md Rakibul Alam1, Kamal Hossain2, Ali Azhar Butt3, Tim Caudle4, Carlos Bazan5
Md Rakibul Alam MEng Student, Pavement Engineering, Department of Civil Engineering Advanced Road and Transportation Engineering Lab (ARTEL) Memorial University of Newfoundland St.John’s, Newfoundland, A1B3X5, CANADA Email: [email protected] (corresponding author)
Kamal Hossain, PhD, PEng Assistant Professor, Department of Civil Engineering Advanced Road and Transportation Engineering Lab (ARTEL) Memorial University of Newfoundland St.John’s, Newfoundland, A1B3X5, CANADA Email: [email protected]
Ali Azhar Butt, PhD, Aff. M.ASCE Assistant ProjectDraft Scientist, Project Manager University of California Pavement Research Center 3301 Apiary Drive, Davis, CA 95616, USA Email: [email protected]
Tim Caudle Co-op Student Department of Civil Engineering Advanced Road and Transportation Engineering Lab (ARTEL) Memorial University of Newfoundland St.John’s, Newfoundland, A1B3X5, CANADA Email: [email protected]
Carlos Bazan, PhD, PEng Assistant Professor, Department of Civil Engineering Engineering Chair in Entrepreneurship Memorial University of Newfoundland St.John’s, Newfoundland, A1B3X5, CANADA Email: [email protected]
Word Count: 4,849 words + 4 figures (250 words per figure) + 5 tables (250 words per table) = 7,099 words
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ABSTRACT
Although pavement maintenance and rehabilitation (M&R) techniques are usually examined in economic terms, there is a growing need to address their environmental footprints.
The objective of this study is to assess the environmental impacts of M&R techniques. LCA can help in the decision-making process of selecting suitable maintenance techniques based on their environmental impacts. This study investigates: patching, rout & sealing, hot in-place recycling, and cold in-place recycling. Global warming potential, acidification potential, human health particulate, eutrophication potential, ozone depletion potential and smog potential are estimated as environmental impacts for each maintenance activity. Materials, equipment use (for construction and M&R), and transportation were the main elements considered. A sensitivity test is performed to identify the significant factors for theDraft LCA. The study concluded that GWP was the most important impact category. Rout & sealing and CIR produced the lowest GWP emissions. Notably, pavement patching and HIR showed significant detrimental environmental impacts.
Keywords: Life Cycle Assessment (LCA), Pavement Maintenance & Rehabilitation,
Environmental Impacts, Global Warming Potential, Pavement Maintenance Activities.
I INTRODUCTION
Addressing the leading factors of climate change is one of the major global issues in today’s time. Therefore, substantial research is being conducted to study the environmental impacts of road pavement designs and construction practices using life cycle assessment (LCA) methodologies. Besides the construction of new roads, numerous maintenance and rehabilitation
(M&R) projects are performed to keep roads functional. For example, the operation, construction and maintenance activities of roads in Canada cost $1160 million in 2011-12 (Transport Canada
2011). Decision support tools such as the LCA are thus needed in order to perform comparisons
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among different pavement M&R techniques in terms of environmental impacts and make informed
decision.
LCA features a cradle-to-grave approach, assessing critical stages of an asset’s life. LCA
requires an inventory of project parameters and corresponding data, and it provides an impact
assessment system that reflects on the environmental footprint for each critical stage of the asset.
For pavement, this includes material (process and production), construction, use, M&R and the
end-of-life (EOL) stages. Construction and M&R stages require considerable amounts of materials
and transportation and can cause significant environmental impacts especially when frequently
required over the entire pavement life; thus, it is imperative to determine which maintenance
techniques or practices can minimize environmentally footprints.
The City of St. John’s (NewfoundlandDraft and Labrador, Canada) has a unique climate, with
excessive precipitation throughout the year as well as extreme winters and moderate summers
(St.John’s 2019) (Ali et al. 2018; Colin and John 1998). The City of St. John's has an annual
‘Streets Rehabilitation Program’ to rehabilitate various streets throughout the city, with an
investment of over $20 million yearly (Bonnell 2016). By using LCA, the goal of this study is to
determine which pavement M&R techniques among pavement patching, rout and sealing, hot in-
place recycling (HIR) and cold in-place recycling (CIR) are more environmental friendly.
This paper is organized as follows: Section II briefly summarizes the literature review on
the topic to provide a broad perspective of previous research. The objectives of this research are
described in Section III, and Section IV provides the analytic approach including the sensitivity
test and experimental setup in Athena Pavement LCA. Section V provides the evaluation of the
emission report and further analysis of the emission results corresponding to each maintenance
and rehabilitation technique. Based on the different emission categories, Section VI comparatively
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interprets which M&R approach is more appropriate and environmentally friendly for each
emission category. Conclusions from this study are drawn in Section VII. Finally, limitations of
this research and the scope for further research are discussed in Section VIII.
II LITERATURE REVIEW
Life cycle assessment is established as a promising technique to quantify the environmental
impact of pavements in its lifetime (Santero et al. 2011). In general, most studies have been
conducted by considering energy consumption and airborne emissions (most commonly
greenhouse gases). This literature review has been performed bearing in mind the questions
relevant to the environmental effect due to asphalt pavement M&R activities. In the past decades, numerous researchDraft has been conducted to evaluate the environmental impacts of asphalt and concrete pavements. Häkkinen and Mäkelä (1996) conducted a
comprehensive comparative study to evaluate the environmental impacts of stone-mastic asphalt
and doweled joint plain concrete pavement (JPCP) using LCA. They selected a 1 km roadway in
Finland with a design life of 50 years as the functional unit of the study. They concluded that
asphalt pavement consumed twice the amount of renewable energy as concrete pavement
considering feedstock energy of bitumen (feed stock energy is defined as “heat of combustion of
a raw material input that is not used as an energy source to a product system, expressed in terms
of higher heating value or lower heating value” (International Organization for Standardization,
2006)). However, the environmental burdens from construction and M&R stages for asphalt pavement were lower than the impacts from high strength concrete production and construction stages (Häkkinen and Mäkelä 1996). In a different study, Roudebush (1996) quantified that asphalt pavement required 90.8% more energy than concrete pavement because of the “use” stages and more frequent “maintenance” stages. That is, more frequent maintenance including milling the
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existing pavement surface and resurfacing it with new asphalt increases the demand for raw
materials which eventually results in substantial energy consumption (Roudebush 1996).
In the advent of the twenty first century, the Finnish National Road Administration
(Mroueh et al. 2000) studied LCA for roads focusing on construction and M&R stages. 1 km of a
highway section was selected as functional unit. Though detailed specifications of necessary
construction equipment and their productivity were missing, a single environmental score system
for determining total environmental burden was a novel development from the LCA research
project. The authors concluded that asphalt production, crushing of aggregate material and
materials transportation were the main contributors to the environmental impacts. In a Swedish
study (Stripple 2001) 1 km of a road was considered as the functional unit and an LCA was
performed including the road marking, Drafttraffic signage on pavement, roadside vegetation etc. for
JPCP and two types of asphalt pavements (produced by hot and cold methods). Comprehensive
details of equipment were provided by the author in the report and all the stages of road LCA were
considered. The study concluded that CO2 emissions for JPCP was higher than asphalt, and
maintenance of the road was the second largest source of emissions in which NOx emission was
the largest.
Treloar et al. (2004) reported a hybrid LCA for road in Australia considering CRCP,
undoweled JPCP, composite pavement and asphalt pavement. Furthermore, road traffic was also
considered in the analysis. The study concluded that embodied energy of road construction stage
was the most important, followed by the material production, use and M&R stages (Treloar et al.
2004). Meil (2006) conducted research about the life cycle perspective on concrete and asphalt
roadways commissioned by Cement Association of Canada using Athena Pavement LCA tool. In
this study, both energy and global warming potential (GWP) of asphalt pavement and JPCP were
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analyzed. From the analysis, the author concluded that the difference in GWP between both types of pavement was insignificant (less than 10%) (Meil 2006).
Cass and Mukherjee have conducted a case study for pavement operations calculating
GHG emission using hybrid LCA (which is the combination of process LCA and input-output
LCA). The study was conducted for concrete pavement and included both construction and M&R stages (Cass and Mukherjee 2011). Recently in the UK, framework has been developed to evaluate the carbon emission for different types of road M&R. This framework is based on UK specification
PAS 2050 and the asphalt Pavement Embodied Carbon Tool (asPECT) and then implemented in
LCA research (Huang et al. 2013; Itoya et al. 2012). Jullien et al. (2014) found using ECORCE tool that the contribution of the M&R stage is almost one-third of the entire life cycle of a road (A
Jullien et al. 2014). In both cases of GWPDraft and eutrophication potential, less emission have been found for asphalt pavement under MP 98 maintenance policy (which considers a partial renewal of surface layers every 3–5 years). However, when MP04 maintenance policy (which considers more intensive works program, with total surface layer renewal every 11 years) is considered, the results were reported to be vice versa.(A Jullien et al. 2014; Agnès Jullien et al. 2015).
Concurrently, Liu et al. (2014) have introduced an estimation of GHG emission in a pavement LCA study. Reclaimed asphalt pavement (RAP) has reduced almost 50 percent GHGs in the construction stage (Liu et al. 2014). It has also been found that in a full depth reclamation project, the pavement using foam asphalt as the base layer material has prevented almost 60 percent of GHGs, and for surface treatment, WMA substitute approach has prevented 46 percent emissions compared to HMA. According to Inyim et al. (2016), GHG emission has been attributed to asphalt and concrete pavement LCA in equal percentage whereas 21 percent energy consumption has been attributed to asphalt pavement and 79 percent to concrete pavement.
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In summary, most road LCA studies have been performed comparing asphalt and concrete
pavement mainly in terms of energy and different types of maintenance techniques. Considering
the M&R stage of pavement life, almost 67 percent of studies reported that asphalt pavements are
more environmentally friendly than concrete pavements (Inyim et al. 2016) while the rest of the
papers renounced this conclusion. It was difficult to find consistency in studies related to selecting
life cycle stages, functional unit, local specification of road pavement design and LCA tools (Azhar
et al. 2015). Recently, the Federal Highway Administration published pavement LCA guidelines
for the US (Harvey et al. 2011), and the Federal Aviation Administration is following the same
path (Butt et al. 2017). Moreover, the Athena Pavement LCA software tool provides environmental
LCA results for Canadian and selected US regions’ roadways which maintain environmental
results consistent with the US EPA toolDraft for reduction and assessment of chemicals and other
environmental impacts (TRACI) methodology.
III STUDY OBJECTIVES
The goal of this research is to determine the environment impacts of major M&R
techniques for asphalt pavements using LCA. The M&R techniques include asphalt patching,
routing and sealing, hot in place recycling (HIR), and cold in place recycling (CIR). For the LCA
analysis, various project parameters were selected using a statistical sensitivity analysis technique.
The parameters include but are not limited to the specifications of road pavement section and the
evaluation of emission for each M&R in a 30-year life cycle. For the emission analysis, an Athena
Institute’s LCA tool called the Athena Pavement LCA was used.
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IV ANALYSIS APPROACH
To evaluate various M&R techniques in terms of environmental impacts, a statistical technique was considered to determine which project parameters are significant for environmental impact analysis. A sensitivity test was performed for CIR through fractional factorial design in
Design Expert 11. Table 1 presents the factors that play a significant role in the emissions obtained from the statistical program. After the sensitivity test, substantial experimental factors were attributed in the Athena Pavement LCA program along with the necessary specification of materials for the analysis. The objective of this hypothetical study is to compare different asphalt pavement M&R techniques using LCA. Therefore, this comparative study does not cover a road network, rather it is focused on an asphalt pavement project only. As a result, road traffic was not considered in the sensitivity analysis. Draft
Sensitivity Test
For the sensitivity analysis, two types of pavement surface were considered; one of which was titled HMA PG 64-22 indicated as “ NL-1”—a common mix design used in Newfoundland and Labrador and the other was “HL-3”—used in Ontario. Asphalt mix properties are summarized in Table 1. NL-1 was considered according to the mixture design specifications of Newfoundland
Department of Transportation (Department of Transportation and Works, 2011). Similarly, HL-3 was considered according to the Ontario provincial standard specification (OPSS) 310 ( Ministry of Transportation Ontario, 2017). The density of NL-1 is 2.46 ton/m3, greater than that of HL-3
(2.24 ton/m3) according to Athena Pavement LCA database. Two levels (defined as subdivision of factor), namely Granular A and reclaimed asphalt pavement (RAP) mixtures were considered as base/subbase material. Average distance of plant to site was assigned with two levels: 1km and
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4km. If the factor “distance of plant to site” becomes significant for the small values of distance,
certainly for the large value, this factor would be significant. Therefore, the average distance of
plant to site was considered small (1 and 4km) for the sensitivity test. Two levels of pavement lift
were used: 1 and 3. For this test, the shoulder of road pavement also had two levels: paved and
unpaved. Finally, the percentage of affected road was considered to be 5% and 20%. Global
warming potential (GWP) was chosen as a response variable. All of the considered six factors with
two levels for each factor are shown in Table 2. After execution of projects for 32 combinations
of assigned factors through the LCA software, a half fractional factorial design was implemented
in Design Expert 11 using GWP values from LCA report results. Based on the half normal
probability plot (Figure 1) and the p values of the ANOVA results (Table 3), it was concluded that
the LCA system was highly sensitive to Draftthe change of average transport distance between the plant
to site, the percentage of affected road, and the number of pavement lifts.
Overview of Athena Pavement LCA Program
The Athena Pavement LCA, developed by the Athena Sustainable Materials Institute in
Canada, was designed for Canadian conditions and selected US regions, relating to roadway life
cycles. The program includes an adequate material database and allows the user to select design
specification of pavement surface, granular sub-base and base materials and shoulder materials.
Besides material properties, the Athena Pavement LCA program comes equipped with a vast
library of selectable machinery and practices. It also features quantifiable data, such as project
pavement segment length, to adopt a functional unit on which the practices of the case study are
compared. Based on this information, Athena Pavement LCA can analyze all the stages in a
pavement’s life cycle except for the EOL stage.
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After assessment of the specific M&R techniques, the project reports result in an array of
impact categories including emission factors to air, water, and land. For the absolute value, there
are options to select from all the listed measures which include energy consumption, air emissions,
water emissions, land emissions, and resource use. The summary result includes more specific
environmental impact categories, including fossil fuel consumption, acidification potential, global
warming potential, human health respiratory effect potential, ozone depletion potential, smog
potential, and eutrophication potential. For example, to quantify GWP, the emissions in CO2 were measured based on the equivalence from the International Panel on Climate Change’s 100-year time horizon factors (11) as shown in the following equation.
[ ] [ ] 퐺푊푃(푘푔) = 퐶푂2 (푘푔) + 퐶퐻4 (푘푔) ∗Draft23 + 푁2푂 (푘푔) ∗ 296 [1] Similarly, pavement vehicle interaction (PVI) effects can be estimated by providing
pavement roughness and deflection modulus values between major roadway rehabilitations as
input data. Moreover, for the maintenance stage, the sub-columns are labeled to separate material
and equipment from transportation. There is also a total value table and the specified units for each
impact category.
Input data for Athena Pavement LCA tool
To quantify the environmental impacts of various M&R techniques in Athena Pavement
LCA, a number of input parameters are required including project size (in terms of road length)
and project life. A functional unit of a 1 km two-lane asphalt roadway pavement was considered
for a 30 year project life span in St. John’s, NL. The pavement included one pavement lift with
two granular layers (base and subbase), and an unpaved shoulder on both side of the roadway. For
transporting materials, the average distance of plant to site, site to stockpile and equipment depot
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to site was considered to be 30 km in another Canadian study [Manitoba case study (Ahammed et
al. 2016)]. A study in the Netherlands considered distance from plant to site within a range of 44
to 120 km. 30 km distance was considered reasonable to assume, hence was decided to be used for
this study as well. According to updated provincial design and construction standard (Highway
Design Division, Department of Transportation and Works, Government of Newfoundland and
Labrador) issued in April 2017, HMA PG 64-22 (referred as NL1) was considered in the LCA
design section as pavement surface material where base material was granular A and subbase
material was granular C. Granular A was used for the construction of the unpaved shoulder.
In this study, pavement distress was considered 20% of total surface area. In order to
compare the LCA for M&R techniques, expected life of each M&R technique was kept same (5
years). As a result, during 30 years of studyDraft period, maintenance and rehabilitation was performed
five times.
V ANALYSIS AND RESULTS
Rout and Sealing
The first M&R practice analyzed was the rout and sealing technique which produced
35,186 kg of CO2 equivalent as GWP, as summarized in Table 5. As the compound-measured
impact category, GWP became the highest emissions and the lowest value was for ozone depletion
potential, 6.94 × 10 ―6 kg, measured as released Chlorofluorocarbon-11 (CFC-11) in kg.
Asphalt Patching
Similar to the rout and sealing technique, the compound-measured environmental impact
category with the highest emission value was GWP for asphalt patching (50,396 kg). As it can be
seen in Table 5, the lowest impact category was ozone depletion potential, which resulted in
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3.367 × 10 ―6 kg of Chlorofluorocarbon-11 (CFC-11).
Hot In-Place (HIR) Recycling
The third M&R technique analyzed for the case study was HIR (Table 5). When reviewing
the results in the compound-measured environmental impact categories, the GWP produced the
highest emissions, and the lowest emission was the ozone depletion potential. As the representative
of GWP, 14,416 kg of CO2 was emitted out whereas ozone depletion potential occupied 3.83 ×
10 ―7kg of CFC-11.
Cold In-Place Recycling
The fourth M&R technique to be analyzed for the case study was CIR. Similar to all
methods studied, the CIR produced higher values for the GWP category and lowest values for the
ODP category as shown in Table 5. TheDraft GWP emissions for CIR technology equated to 10,450 kg
―7 of CO2 equivalent. For the ODP, the CIR technology equated to 2.24 × 10 kg of CFC-11.
VI COMPARISON BETWEEN FOUR M&R TECHNIQUES
The results show that the GWP and ODP were the highest and lowest impacts, respectively,
for all the M&R techniques. Since the project used diesel as the energy source for operation, CO2 equivalent showed significant amount in the results because of 2.68 kg CO2 production per litre diesel consumption. However, the emissions of CFC-11 were minimal in the project.
Figure 2 presents GWP contribution as the highest compound-measured emission category among the selected four maintenance processes. The CIR technique produced the lowest CO2 eq. emissions, 83.87% during its project life closely followed by HIR technique, which produced
86.63% of CO2 eq. emissions. For asphalt patching, the CO2 emission resulted the highest percentage (92.22%) and thus became the least suitable option among four studied M&R methods
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in terms of GWP.
The results from the pavement patching and HIR techniques can be explained based on the
total number of equipment and equipment time used. Both included technology that used more
diesel as fuel consumption and produced high temperatures during manufacturing materials and
thus resulted in a higher emission of CO2. For the CIR methods, less machinery was used and no
on-site heating machinery was required, leading to less diesel fuel required for operation, hence
producing lower CO2 emissions. Smog potential was the second largest contributor of emissions
for each practice. In addition, 15.06% emission of smog potential was from CIR followed by HIR
(12.51%), rout and sealing (9.76%) and finally asphalt patching (7.28%) as shown in Figure 3. The
reasons behind the higher smog potential of CIR rather than HIR need to be investigated in further
research. Draft
Besides GWP and smog potential, the other emission factors combined to carry
approximately 1% of the environmental burden, where rout and sealing and CIR had the greatest
impact on the percentage of acidification potential (0.96%) followed by HIR (0.78%) and asphalt
patching (0.45%). HH particulate and eutrophication potential percentage were very low for all of
the four M&R techniques (less than 0.1%).
VII CONCLUSIONS
This research adopts a process LCA program to determine which pavement M&R
techniques, among pavement patching, rout and sealing, HIR, and CIR has the most minimal
environmental impacts for a given maintenance project. Based on the LCA results, the following
conclusions are made:
Among six compound-measured environmental impact categories, the global warming
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potential category, measured in emissions of CO2-eq. in kg, held the highest values for all
four M&R techniques including asphalt patching, rout and sealing, HIR and CIR.
Based on GWP, CIR technique produced the lowest percentage of CO2-eq. (83.87%), and
for asphalt patching, the CO2 emission resulted in the highest percentage (92.22%) which
is the least suitable option for M&R methods in light of GWP.
CIR method which requires less machinery with no heating machinery leads to less diesel
fuel for operation, and therefore, causes less reduction of CO2 emissions.
In terms of smog potential, asphalt patching (7.28%) appears as the most promising
approach for pavement maintenance.
Rout and sealing and CIR had the most significant impact on the percentage of acidification
potential (0.96% each) whereasDraft the contribution of HH particulate and eutrophication
potential was minimal for each M&R technique.
Based on our small-scale study it can be concluded that LCA approach works effectively to comprehend the environmental impact of major maintenance and rehabilitation techniques of asphalt pavement. Furthermore, the quantitative analysis of comparison among those M&R techniques assists to take environmentally friendly road treatment decisions prior to application for similar layered combination of asphalt pavement
VIII LIMITATIONS AND FURTHER RESEARCH SCOPE
HIR and CIR are not applicable if there is any structural failure of pavement base/subbase layers. Moreover, HIR is applicable for depth up to 2 inches of pavement layer in practical field.
In this study to circumvent the complexity issue, the reclamation depth was kept constant at a 4 inch depth. In future research, proper remedy for structural failure and different reclamation depths
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can be considered. Every technology associated with the practice was assumed to use diesel fuel
as an energy source. Default technology was set for each practice. Instead of default technology,
different methods i.e., surface recycling, repaving or remixing for HIR; single-unit train, two-unit
train or multi-unit trains for CIR; low-modulus rubberized asphalt, self-leveling silicone etc. for
sealing can be considered for further research. Different methods of performing the M&R activity
require additional technology, which could significantly increase the emission levels. Any of these
changes could shift the balance of the four M&R practices. Similarly, the materials that each
practice can change depending on location and design standard preference by local transportation
and highway officials.
Pavement infrastructure susceptibility includes three basic elements: environmental
protection, economic prosperity and socialDraft acceptability (Reza et al. 2014).Therefore, further LCA
study should be multi-attributed which will evaluate cost-effectiveness and performance of M&R
along with environmental impact (Giustozzi et al. 2012; Yu et al. 2013). Notably, life-cycle cost
analysis (LCCA) could be recommended to integrate with LCA researches.
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Appendix
Table1: Asphalt mixture information
Table 2: Factors for sensitivity test for statistical analysis
Table 3: ANOVA summary
Table 4: Road section design dimensions
Table 5: Impact assessment of the environmental impact categories for different M&Rs
Figure 1: Half-Normal percentage probability plot
Figure 2: Global Warming Potential percentageDraft values of the four analyzed M&R practices
Figure 3: The Smog Potential percentage values of the four analyzed M&R practices
Figure 4: Acidification Potential, Human Health Particulate, and Eutrophication Potential Emissions: The percentages of three compound-measured impact categories
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Table 1: Asphalt mixture information
Asphalt Content Maximum Mix ID Binder Type VMA (%) Density (ton/m3) (% by weight) Aggregate Size NL-1 PG 64-22 6 14 2.46 19mm HL-3 PG 64-28 4 16 2.24 16mm
Draft
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Table 2: Factors for sensitivity test for statistical analysis
Factor Coding Considered LCA Design Letter -1 1 variable designation Avg. distance plant to site (km) A 1km 4km No. of pavement lift B 1 3 Pavement surface asphalt mix type C NL-1 HL-3 Base/Subbase material type D Granular A RAP % of affected road E 5% 20% Shoulder F Unpaved Paved
Draft
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Table 3: ANOVA summary
Sum of Degree of Mean Source F-value p-value Squares freedom Square Model 3.20E+08 3 1.07E+08 1266.31 < 0.0001 A-Avg. distance plant to 2.51E+07 1 2.51E+07 297.71 < 0.0001 site B-No. of pavement lift 2.24E+07 1 2.24E+07 265.75 < 0.0001 E-% of affected road 2.73E+08 1 2.73E+08 3235.49 < 0.0001 Residual 2.36E+06 28 84269.16 R² 0.9927 Adjusted R² 0.9919 Predicted R² 0.9904 Adequacy of Precision 90.4373 Draft
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Table 4: Road section design dimensions
Width Thickness Element name Material (m) (mm) Lane 1 Lift 1 NL-1 3.5 60 Lane 2 Lift 1 NL-1 3.5 60 Left Unpaved Shoulder Granular A 0.5 40 Right Unpaved Shoulder Granular A 0.5 40 Granular Layer 1 (Base) Granular A 8 100 Granular Layer 2 (Subbase) Granular C 8 100 Draft
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Table 5: Impact assessment of the environmental impact categories for different M&Rs
Rout and sealing Asphalt patching HIR CIR
Impact Category and and and and Total Total Total Total Materials Materials Materials Materials Materials Transport Transport Transport Transport Equipment Equipment Equipment Equipment GWP 34,931 255 35,186 48,453 1,943 50,396 12,244 2,173 14,416 8,135 2,315 10,450 (kg CO2 eq.) Acidification Potential 376 2.5 378 2267 19 245 108 21 129 97 22 119 (kg SO2 eq.) HH Particulate 29.36 0.13 29.50 14.69Draft1.03 15.72 7.59 1.16 8.75 6.97 1.23 8.21 (kg PM2.5 eq.) Eutrophication Potential 14.75 0.16 14.91 10.24 1.16 11.40 5.17 1.30 6.47 4.54 1.38 5.92 (kg N eq.) Ozone Depletion 6.94 × 10 ―6 8.93 × 106.94―9 × 103.299―6 × 10 ―6.786 × 103.367―8 × 103.08―6× 10 ―7.587 × 103.83―8 × 101.44―7 × 108.08―7 × 102.24―8 × 10 ―7 Potential (kg CFC-11 eq.) Smog Potential 3,771 80 3,851 3,391 585 3,980 1,422 659 2,082 1,173 703 1,876 (kg O3 eq.)
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Draft
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Draft
Figure 1: Half-Normal percentage probability plot
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Figure 2: Global Warming Potential percentage values of the four analyzed M&R practices Draft
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Figure 3: The Smog Potential percentage values of the four analyzed M&R practices Draft
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Figure 4: Acidification Potential, Human HealthDraft Particulate, and Eutrophication Potential Emissions: The
percentages of three compound-measured impact categories
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