Structural classification evaluation estimated by PCR of airport pavements with reclaimed asphalt concrete overlay containing RAP

ABSTRACT

The search for efficient and sustainable airport pavement solutions has been ongoing, driven by the need for more durable pavements and fewer restorations. Despite advances, many runway interventions occur due to mismatches in structural support capacity and load levels, as well as functional issues. As a result, milling deteriorated pavement coating layers generates considerable amounts of RAP (Reclaimed Asphalt Pavement). RAP has demonstrated positive results when incorporated into new pavements, primarily in highway paving, and supports both economic and sustainability goals. This study analyzes the structural performance of airport pavements where the coating layer was replaced with recycled asphalt mixtures containing RAP, in lieu of conventional asphalt concrete. Experimental and computational analyses were conducted, including back-calculation of pavement structures at three aerodromes, and then proposing and evaluating new pavement sections mechanically. The design preserved existing granular layers and replaced only the coating layer with a recycled RAP mixture, followed by a seal coat to reduce weathering risk. The mixtures were hot mixed with 100% RAP and a recycling agent. Results showed superior structural responses for the new sections, with a significant increase in the Pavement Classification Rating (PCR). This supports the viability of using RAP in airport pavements and its environmental benefits from reusing residue.

Keywords:
RAP; Airport pavements; Asphalt mixture; Back-calculation; ACR-PCR.

1. INTRODUCTION

Brazil has an area of approximately 8.5 million km², which poses a challenge for national logistics to maintain the transportation matrix efficiently, since even internally, the displacements carried out in the country are substantial. Thus, there is a constant need for implementation and maintenance of transportation infrastructure designed to interconnect geographic spaces [¹].

Given the need for rapid transport in current societal dynamics, the airport sector becomes one of the key assets in the challenge of improving mobility. This is noticeable when observing the CAPEX and OPEX investment indices in the sector [²], and the constant interest of private initiative in exploring and managing the infrastructure, in addition to innovations regarding modal regulation, aiming not only at operational functionality but also at solutions for improving infrastructure performance.

Within this sphere, airport pavements, especially runways, play a fundamental role in ensuring safety and operational efficiency, encompassing challenges not only in the expansion of sector facilities but mainly in maintaining pavement quality levels, involving management mechanisms from design to operation, with quality control indices considerably higher compared to those attributed to the highway modal [³,⁴,⁵, ⁶], states that one of the management mechanisms comprises interventions performed on the infrastructure, such as pavement maintenance and rehabilitation, with the purpose of elevating the functional and structural condition. However, these interventions generate high quantities of waste from pavement structure milling and asphalt mixture rejection, resulting in an environmental liability [⁷, ⁸].

Considering the occurrence of climate events, the need for increasingly resilient infrastructures becomes evident [⁹], as well as the establishment of sustainable methodologies and techniques, in addition to the search for innovative solutions with lower environmental impact that present structural and functional performance equal to or superior to conventional practices established in the paving industry [¹⁰].

However, the current paving industry still contributes a significant percentage of Greenhouse Gas (GHG) emissions, which implies generation at levels well above established targets, considering that Brazil has committed to reducing its emissions by 37% by 2025 and 43% by 2030, to meet the Paris Agreement in limiting critical warming to 1.5°C above pre-industrial levels [¹¹]. Among the goals to be achieved for this purpose are improvements in transportation infrastructures according to Ordinance No. 622 of the Ministry of Transportation, which establishes guidelines for resource allocation in concession contracts aimed at developing resilient infrastructure, mitigating GHG emissions, and energy transition [¹², ¹³], and other methodologies, such as environmental labeling and product declarations in the paving industry [¹⁴, ¹⁵].

From this perspective, the importance of research on pavement recycling can be evidenced, regarding the reuse of reclaimed material in structural and surface layers, use of warm-mix and cold-mix asphalts, use of bio-binders, vegetable oil and waste oil additives, use of plastics in mixtures and other alternative materials, all within the net-zero-carbon perspective [¹⁶,¹⁷,¹⁸,¹⁹,²⁰].

According to research by [²¹, ²²], pavement structure with RAP (Reclaimed Asphalt Pavement) reduces GHG emissions by around 13% and 25% compared to scenarios without RAP. This is possible mainly due to the reduction in demand for virgin binder in mixtures with RAP consequently a reduction in the production process of this binder [²²,²³,²⁴,²⁵]. As a result, there is also a decrease in the use of aggregates, even though the percentage of gas emissions in aggregate extraction and production is quite small, corresponding to about 9% [²⁶]; there is the transportation factor of this material, wich also generates a considerable impact on pollutant emissions.

Therefore, expanding the possibilities of implementing these practices, and considering that the design of pavement structures for highway purposes using RAP is already an established practice [²⁷], the present work evaluated the structural behavior of conventional asphalt concrete airport pavements in service through backcalculation analysis, and redesigned the pavement structures with the surface layer composed of hot-recycled asphalt concrete with incorporation of 100% RAP, replacing conventional aggregates and binders, in order to analyze from a mechanical performance standpoint whether the structure would meet the existing airport traffic at the aerodrome without causing structural damage and performance loss.

2. RECYCLED ASPHALT MIXTURES WITH RAP INCORPORATION

Among the advantages of using recyclable materials as new pavement materials, the reduction in construction costs, conservation of aggregates and binders, preservation of existing pavement geometry, maintenance of drainage conditions, environmental preservation, energy conservation, structural homogenization, structural readjustment, and rapid runway reopening can be highlighted [²⁸].

In analyses of material properties and with monitoring of the performance level of layers produced with RAP insertion, there is evidence that the material presents good behavior when percentages are incorporated in new mix designs, and/or when it composes the new mixture as a whole, with reuse of aggregates and remaining binder [²⁹].

Given its large-scale utilization, RAP has been the main recycled material incorporated in new mixtures and granular layers in the paving industry [¹⁶]. According to [⁹], the country that makes the most use of reclaimed material in asphalt mixtures, using about 80% of all available material, has been Germany, followed by the Netherlands and France, with 75% and 40% respectively.

The fact is that the percentage of RAP incorporation in new mixtures can generate economic and sustainable gains, reduce consumption of virgin materials [³⁰,³¹,³²], and significantly reduce greenhouse gas emissions linked to energy consumption expended in plant production [³³], given its use as a solution for pavement maintenance and rehabilitation [³⁴].

Therefore, there are findings that the mechanical performance of asphalt mixtures with RAP, especially regarding rutting resistance, are similar to and even superior when compared to conventional asphalt mixtures [¹⁶]; however, the percentage of material incorporation does not always result in proportional performance.

Studies conducted with various RAP contents incorporated by mass, ranging from 10% to situations of total material utilization with 100% reclaimed material, demonstrated a similarity in mixture stiffness gain, increase in resilient modulus, dynamic modulus, elastic modulus, tensile strength, and retained tensile strength, as the RAP content in the mixture increased [¹⁰, ¹⁶, ²⁹, ³⁵,³⁶,³⁷,³⁸,³⁹,⁴⁰]. However, when analyzing fatigue life, the trend changes, resulting in susceptibility to premature cracking for mixtures whose contents exceed 45% [¹⁶].

In this context, where recycled mixtures present favorable performance for rutting but low fatigue life if high contents are incorporated, the need for recycling agents that aim to reduce stiffness and improve mixture lubricity may be necessary, as these have a high quantity of maltenes, which act in balancing and modifying the maltene structure of the oxidized binder [⁴¹], in order to ensure better performance in material elastic recovery, as they reduce aged binder viscosity and improve adhesion and cohesion properties [⁴², ⁴³].

What is little defined is standardization regarding the type and percentage of incorporation of this additive in recycled mixtures, since there is variability, whose raw materials range from petroleum derivatives, vegetable oils, waste oils, and bio-binders [⁴⁴, ⁴⁵], and percentages oscillate from analyses that relate to binder type and recycling rate.

Therefore, it is noted that optimizing the use of Recycling Agents (RA) in recycled asphalt mixtures depends on a careful balance between the amount of RAP, the proportion of RA, and the recycling rate [⁴⁶], and that precise adjustments in these parameters can lead to significant improvements in the quality and performance of the recovered binder, thus maximizing the environmental and economic benefits of recycled asphalt mixture applicability, and directly on pavement performance.

2.1. Performance of asphalt pavements submitted to extreme loading

The performance of pavements, specifically asphalt mixtures, is related to resistance to stresses arising from dynamic loading imposed on the structure, in addition to climatic actions [⁴⁷]. To attest to this, and to determine whether mixtures will provide serviceability throughout the pavement’s service life, parameters that describe the mechanical performance of mixtures due to deformations and deteriorations that may occur are analyzed.

Thus, asphalt mixtures are tested with the objective of predicting their behavior when pavements are under service conditions, that is, subject to extreme loads and diverse meteorological conditions, and also to perform Life Cycle Analysis (LCA) [⁴⁸].

In this context of evaluating the mechanical properties and LCA of mixtures, aspects related to rutting resistance and fatigue life have been the most considered, whether when designing the structure or when performing the mix design of the surface layer, seeking to adapt the structure to the stress levels that the pavement will be subjected to.

And considering that design adopts knowledge about pavement mechanics, and this discipline combines knowledge of continuum damage mechanics, widely used in determining the stress and strain state of layers, soil mechanics, employed in characterizing the behavior of soils and granular materials, and fracture mechanics, applied to more reliably estimate the cracking pattern that occurs in the layers [⁴⁹], aiming to provide fundamentals for structural design and pavement performance prediction.

In this logic, not only structural aspects are analyzed, but functional conditions are also predicted at the time of design and mix design study, since control in material selection, mixture type, and gradation has a direct relationship with the mechanical performance of the pavement and with functionality indicators [⁵⁰].

Thus, for better structural evaluation of pavements, methods should be used that consider the stress-strain relationship of pavement layer materials, obtained through laboratory tests and back-calculation analyses, that is, deflection measurements induced in the pavement with application of dynamic loads [⁵¹].

It is important to emphasize that, in a pavement structure, the loading exerted during the passage of a load is transient, and both soils and granular materials of the foundation exhibit behavior whose stress-strain level is nonlinear and influenced by various conditions [⁴⁹]. Asphalt materials, in turn, have properties sensitive to the speed of load application and temperature, so that when subjected to a load cycle, they will experience deformations, which vary only in relation to their relative proportion, according to the nature of the material, its integrity conditions, and the time of load application [⁵²].

In this context, considering that the pavement behaves as an elastic layer system, based on the principles of elasticity of geotechnical materials, there are hypotheses that each layer is homogeneous, elastic, and isotropic, with the surface layer having finite thickness and the subgrade infinite thickness, and regarding the surface condition, there are no shear stresses in the layer, being free of normal stresses outside the load application boundaries [⁵³].

Assuming these hypotheses, [⁵³] states that it is possible to establish the condition that a pavement in use is found, through computational back-calculation tools, fed with input data necessary for calculating deformations, stresses, and deflections in pavements in service, comprised of information about material properties (Poisson’s ratio and elastic modulus), construction method (layer thicknesses), and acting forces (magnitude and load distribution).

However, there are also possibilities to redesign existing structures, in order to propose improvements and reinforcements to the layers, with the objective of extending pavement performance and increasing its current capacity, configuring as an engineering solution, with the asphalt surface layer recycling technique being characterized as an alternative for gaining structural performance, especially structures that are subject to high and seasonal loading levels, which is the case of airport pavements.

2.2. RAP on airport pavements

The control guidelines for materials and execution techniques attributed to airport pavement construction tend to be much more restrictive compared to highway pavement construction. Regarding the use of alternative materials applied to the sector, regulatory agencies present resistance regarding applicability, and this resistance may be associated with the success of conventional material usage, uncertainty regarding the minimization of functional and structural quality indices of the pavement, and mainly due to lack of more in-depth studies.

Thus, considering the advancement in the highway area regarding new pavement materials, some research has also been conducted in the airport area, initially highlighting the possibilities of RAP applicability in the design of new asphalt mixtures for use on runways.

Therefore, the through AC 150/5370-10H [⁵⁴] brings some restrictions regarding RAP use, recognizing the material’s applicability only in binder courses and/or shoulders with a maximum incorporation percentage of 30%, and attributing its use under these conditions to structures whose loading is less than 60,000 lb, whereas for demands above the established value it requires a better study of mixture performance conditioning the agency’s approval, and with assurance of executive control in which the layer thickness is compacted within a limit of 300 mm.

Given the known performance of asphalt mixtures with RAP in highway pavements, it is noted that the structure presents good rutting behavior and a fatigue life inversely proportional to the incorporated content; in this regard, the concern is notable that the stiffness gain could impact operational safety, generating susceptibility to jet blast events due to the presence of FOD (Foreign Object Damage).

Therefore, among the research conducted, [⁵⁵] evaluated the use of reclaimed material from the surface layer in the composition of a new asphalt mixture, incorporating 5% to 10% RAP for use in airports in Australia, where it was confirmed that, although RAP contents were low, there were performance gains regarding rutting [⁵⁶], on the other hand, evaluated the use of RAP in a binder course with an incorporated percentage of approximately 60% with the addition of a recycling agent to improve mixture workability, and the results obtained showed good mechanical performance and low deformability.

Due to the intrinsic properties of hot-mix asphalt with RAP, such as higher stiffness, low deformability, and high energy storage capacity, it is notable that the structural capacity of these pavements, estimated by the ACR-PCR methodology, tends to present more attractive initial values, due to higher moduli.

The ACR-PCR methodology detailed in AC 150 5335-5D [⁵⁷] is designed to evaluate airport pavement strength under the elastic-linear principle. It uses crucial data for damage predictability, such as the operating aircraft mix that reflects on the number of coverages and the impact of various landing gear configurations, and the pavement structural package, which analyzes the stiffness moduli of layers, obtained by back-calculation from deflection basin measurements (layer deformation).

However, through these considerations, it is possible to achieve the discretization of structural damage analysis points [⁵⁸], and this allows obtaining the pavement’s CDF (Cumulative Damage Factor) in a more rational manner, enabling a pragmatic analysis of the demand imposed on the pavement structure.

Furthermore, a detailed analysis must consider the subgrade soil strength to correlate the loading level with the behavior of upper layers, so that there is load distribution until the loading reaches reduced magnitude at the foundation soil [⁴²]. This will impact on CDF less than 1, a fact that when CDF reaches unit value at any Offset position, it is considered that the total structural consumption of the pavement has occurred through accumulated damage. In this way, it is possible to identify critical damage points and consequently greater assertiveness in pavement structure management.

Moreover, it should be emphasized that PCR does not constitute an intrinsic property of the pavement, and thus, a result different from that mathematically calculated can be accepted [⁵⁹].

3. METODOLOGHY

By establishing the condition and service life of a pavement structure, the methodology was understood through back-calculation of the runways at three aerodromes, followed by redesigning the pavement structures with hot-recycled asphalt concrete layers incorporating 100% RAP, and sealed with a polymer sealant layer, in order to then assess the estimated load capacity of these pavements by the PCR (Pavement Classification Ratio), according to the flowchart in Figure 1.

Figure 1
Research flowchart.

According to the flowchart, data acquisition from the PPDs of the three aerodromes involved determining the materials of the layers using direct methods such as GPR (Ground Penetrating Radar), DCP (Dynamic Cone Penetration), SPT (Standard Penetration Test), and manholes, as well as retroanalysis of the structure using FWD equipment – Falling Weight Deflectometer equipment to measure the deflections existing in the pavement structure, and BAKFAA software to obtain the actual modules, and redesigning in FAARFIELD software, considering the same number of passages covering the mix of aircraft existing at the aerodromes, changing only the coating layer, replacing it with recycled asphalt concrete (CA) recycled and sealed with a polymer sealant layer, whose values for the recycled asphalt concrete with RAP were found by [¹⁰].

3.1. Aerodromes and airport pavements data

The aerodromes in the study are small, not conceded, under public administration by a specific regulatory agency for regional airports in the country, and under the supervision of state agencies in the geographical region to which the aerodrome belongs. Both aerodromes have a single runway structure with asphalt concrete pavement, whose designation of runway heads, runway length and width, and structural capacity of the pavement estimated by the PCR are detailed in Table 1.

Table 1
Aerodrome and runway data.

AERODROME A-OPERATION IFR DAYTIME
RWY	Length RWY (m)	Widht RWY (m)	PCR calculated
09-27	1,515	30	440/F/B/X/T
AERODROME B-OPERATION VFR
RWY	Length RWY (m)	Widht RWY (m)	PCR calculated
04-22	1,500	30	210/F/B/X/T
AERODROME C-OPERATION IFR
RWY	Length RWY (m)	Widht RWY (m)	PCR calculated
09-27	2,110	45	380/F/B/X/T

It should be emphasized that the aerodromes in question operate with distinct aircraft mixes and varying numbers of takeoffs between them due to their capacities also being distinct. Therefore, to quantify the operating aircraft mix at each aerodrome, a query was conducted in the metadata of the National Civil Aviation Agency [⁶⁰] which provides a series of open data on operations performed at Brazilian airports, and for analysis, data on airline companies responsible for operations, year and month of operations, origin airport, number of takeoffs, available seats, paying passengers, and complimentary passengers were considered.

And for information processing, operations by airport for the year of analysis were filtered in the database, and the average number of seats per flight was calculated by dividing the seats variable by the takeoffs variable. Subsequently, the aircraft that operated at the airport in the year of analysis were defined through a survey of aircraft fleets used by airlines; and finally, knowing the average number of seats per takeoff, the airlines’ aircraft and their respective capacities, it was possible through correlation to estimate the aircraft mix for the studied airports, as evidenced in Table 2.

Table 2
Mix of aircraft operating at aerodromes.

AERODROME A
Aircrafts	Take-offs	Annual growth rate
Cessna 208B	107	3%
AERODROME B
Aircrafts	Take-offs	Annual growth rate
ATR 72-600	324	3%
AERODROME C
Aircrafts	Take-offs	Annual growth rate
Embraer E-195	124	3%
Boeing 737-800	121	3%
Airbus 319	9	3%
Airbus 320	8	3%
Airbus 320 neo	1	3%

It should be noted that an annual growth rate of 3% was set for all aerodromes. This figure depends on extrinsic factors that are not covered by the study, but it was considered necessary for the calculations and back analysis of pavement structures.

4. RESULTS AND DISCUSSIONS

4.1. Back-calculation analysis process for runways

The back-calculation process followed the AC 150 5320-6G [⁶¹], which provides the possibility of calculating the load-bearing capacity of pavement layers that are in service through non-destructive analyses, using information from pavement deflection basins, layer thicknesses, and the type of constituent material of each layer.

The process used to conduct the back-calculation performs analyses opposite to those considered in a pavement design project; instead of determining the thickness of each pavement layer based on assumed layer strengths, the reverse calculation involves solving for pavement layer strengths based on assumed uniform thicknesses, such that layer strength is referred to in terms of Young’s modulus or elastic modulus.

The estimated moduli represent the elastic response of the pavement and subgrade to the applied loading, which mobilizes “reversible” displacements at the structure’s surface, and the total deflection of the structure is the sum of the individual contributions of each material constituting the pavement/subgrade system.

Therefore, back-calculation of layer material moduli of pavements is advantageous for structural evaluation, since it provides information on the mechanical properties of the structure under “in situ” conditions, commonly used as input data for analyzing the maintenance and/or restoration of acceptable pavement characteristics for its best performance throughout its service life.

Therefore, the back-calculation process followed the same methodology for the three aerodromes in the study, where structural evaluation of the pavement was performed through FWD testing, with the deflectometry readings obtained by applying a seating load of 41 kN and a test load of 80 kN on all structures evaluated on the Airside.

The analysis was performed every 20 meters along the entire runway length, on both the right edge and left edge, 3 meters from the centerline, this distance being known as the most heavily loaded area, resulting from the landing gear configuration of operating aircraft.

After conducting the test, data processing for back-calculation proceeded with basin normalization, performed through correction of the load applied in the test, and with correction of deflection basins to the standard temperature of 25°C, using the formulation developed by [⁶²], demonstrated in equation 1.

(1) $$d_{25}=\frac{d_p}{[\{\frac{h_{CA}}{1000}\times (T-25)\}+1]}$$

Where:

d25: deflection adjusted for temperature of 25°C (10^-2 mm);

dp: deflection on runway (10^-2 mm);

hCA: surface layer thickness (cm); e,

T: surface temperature measured during the test (°C).

However, the BAKFAA software does not consider calculations for correction of deflection basins to a standard temperature, and knowing that asphalt surface layers are sensitive to temperature variations, which can cause variability in the results found for their performance characteristics, corrections were performed only on basins with large temperature variations, that is, those in which temperatures between 16°C and 21°C above the reference temperature of 25°C were measured, and for measurements D0, D1, and D2 which represent readings of elastic compression of asphalt concrete [⁶³, ⁶⁴].

After performing the corrections and having the usual data for backcalculation, sections of the runway pavement that have similar mechanical behavior were defined, a fact explained because an airport pavement structure has varying load-bearing capacity requirements along the runway length, due to the different stages of aircraft operation and aircraft ACR.

Therefore, based on the presumption that there would be runway points that would present distinct load-bearing capacities, the cumulative difference method according to AC 150/5370 – 11B [⁶⁵] was adopted as a mechanism for defining homogeneous segments.

The cumulative difference method for the study was based on the analysis of maximum deflections (D0 measured at the first geophone) to then analyze the accumulated values of the difference between evaluation points. Since deflection measurements are discrete, that is, they are known only at stake positions, it was necessary to adapt the deflection data so that they were treated as continuous along the entire runway length. For this purpose, the concept of average deflection was created, with the average deflection between stakes i^-1 and i demonstrated in equations 2 and 3.

(2) $${\overline{D}}_1=D_1$$

(3) $${\overline{D}}_1=\frac{D_{i-1}+D_i}{2};i\ge 2$$

Subsequently, the longitudinal deflection area along the PPD extension can be calculated using equations 4 and 5.;

(4) $$A_i=\overline{D_i}\mathrm{\Delta }{l}_i$$

(5) $$A_T={\displaystyle {\sum }_{i=1}^N{A}_i}$$

Where Aⁱ is the longitudinal deflection area between stake i^-1 and stake i, A ^T is the longitudinal deflection area accumulated along the entire Runway, and Δ li is the distance between stake i^-1 and stake i. With this, it was possible to determine the accumulated values of the differences (Zⁱ) using equation 6;

(6) $$Z_i={\displaystyle {\sum }_{k=1}^i{A}_K}-\left(\frac{A_T}{L_C}\right)P_i$$

Where Pⁱ is the position of the stake, and L^c is the total length of the Runway.

After performing the calculations, the data were obtained and a graph was plotted of the cumulative difference values by position on the runway, as shown in Figure 2. And observing the plotted profile, some inflection points can be noted along the runway length, which indicate the 0ccurrence of a discontinuity in the mechanical properties of the runway layer materials, which was defined as the transitions of homogeneous segments.

Figure 2
Profile outline in homogeneous segments of the runway.

Still in the back-calculation process, it was necessary to know the stratigraphy of the runway structure of the study aerodromes, obtaining the thicknesses of existing layers. Therefore, to determine the average value of layer thicknesses in each homogeneous segment, the GPR tool was used, and inspection windows were opened at the runway edges, with the use of DCP to consolidate information about the thicknesses found. The data obtained in the test are detailed in Figure 3.

Figure 3
Thicknesses of pavement layers measured by GPR.

When analyzing the graph in Figure 3, it was verified that the raw data for determining layer thickness presented certain dispersion, evidenced by the formation of peaks associated with atypical values, which needed to be eliminated through statistical treatment.

Thus, for outlier exclusion, the boxplot methodology was adopted to determine the representative quartile and calculate the average thicknesses of each homogeneous segment. Such a definition regarding the use of boxplot methodology is justified by the ease in classifying discrepant values through quartile analysis, considering as coherent the thickness values located between the first and third quartile of the diagram, and disregarding those that exceeded the limits, called outliers.

After performing the statistical treatment, new thicknesses were calculated for the pavement layers, considering a 95% confidence level in a normal distribution. Table 3 presents information regarding the pavement layer thicknesses of aerodromes A, B, and C, obtained after statistical treatment of the data and calculation of average values.

Table 3
Thickness and modulus data assigned to the structural layers of the runways.

AERODROME A
RIGHT LANE-RWY								LEFT LANE-RWY
SEGMENT	LAYER	MATERIALS	SEED MODULUS (MPa)		POISSON’S	THICKNESS (mm)	TOTAL THICKNESS (mm)	THICKNESS (mm)	TOTAL THICKNESS (mm)
SH-01	Coating	HMA (CAP 50-70)	3,500		0.30	107	372	97	424
	Base	Well graded gravel	500		0.35	104		139
	Sub-base	Dry macadam	200		0.35	161		188
	Subgrade	Laterite clay soil	140		0.40	–		–
SH-02	Coating	HMA (CAP 50-70)	3,500		0.30	86	405	82	449
	Base	Well graded gravel	500		0.35	101		140
	Sub-base	Dry macadam	200		0.35	218		227
	Subgrade	Laterite clay soil	140		0.40	-		–
SH-03	Coating	HMA (CAP 50-70)	3,500		0.30	73	362	66	454
	Base	Well graded gravel	500		0.35	147		205
	Sub-base	Dry macadam	200		0.35	142		183
	Subgrade	Laterite clay soil	140		0.40	–		–
AERODROME B
RIGHT LANE-RWY								LEFT LANE-RWY
SEGMENT	LAYER	MATERIALS	SEED MODULUS (MPa)		POISSON’S	THICKNESS (mm)	TOTAL THICKNESS (mm)	THICKNESS (mm)	TOTAL THICKNESS (mm)
SH-01	Coating	HMA (CAP 50-70)	3,500		0.30	43	505	50	552
	Base	Well graded gravel	500		0.35	274		258
	Sub-base	Dry macadam	200		0.35	188		244
	Subgrade	Laterite clay soil	150		0.40	–		–
SH-02	Coating	HMA (CAP 50-70)	3,500		0.30	43	524	48	532
	Base	Well graded gravel	500		0.35	275		260
	Sub-base	Dry macadam	200		0.35	206		224
	Subgrade	Laterite clay soil	150		0.40	–		–
SH-03	Coating	HMA (CAP 50-70)	3,500		0.30	42	469	45	544
	Base	Well graded gravel	500		0.35	279		267
	Sub-base	Dry macadam	200		0.35	148		232
	Subgrade	Laterite clay soil	150		0.40	–		–
SH-04	Coating	HMA (CAP 50-70)	3,500		0.30	40	425	42	509
	Base	Well graded gravel	500		0.35	270		269
	Sub-base	Dry macadam	200		0.35	115		198
	Subgrade	Laterite clay soil	140		0.40	–		-
AERODROME C
RIGHT LANE-RWY								LEFT LANE-RWY
SEGMENT	LAYER	MATERIALS	SEED MODULUS (MPa)	POISSON’S		THICKNESS (mm)	TOTAL THICKNESS (mm)	THICKNESS (mm)	TOTAL THICKNESS (mm)
SH-01	Coating	HMA (CAP 50-70)	3,500	0.30		71	487	68	516
	Base	Well graded gravel	500	0.35		186		195
	Sub-base	Plain gravel	250	0.35		230		253
	Subgrade	Laterite clay soil	150	0.40		–		–
SH-02	Coating	HMA (CAP 50-70)	3,500	0.30		66	536	60	576
	Base	Well graded gravel	500	0.35		188		207
	Sub-base	Plain gravel	250	0.35		282		309
	Subgrade	Laterite clay soil	150	0.40		–		–
SH-03	Coating	HMA (CAP 50-70)	3,500	0.30		76	490	69	512
	Base	Well graded gravel	500	0.35		168		189
	Sub-base	Plain gravel	250	0.35		246		254
	Subgrade	Laterite clay soil	150	0.40		–		–
SH-04	Coating	HMA (CAP 50-70)	3,500	0.30		70	514	78	524
	Base	Well graded gravel	500	0.35		183		161
	Sub-base	Plain gravel	250	0.35		261		285
	Subgrade	Laterite clay soil	150	0.40		–		–

4.2. Evaluation of the structural capacity of the existing pavement estimated by PCR

Following the process of understanding the pavement structure of the runways at the aerodromes in this study and obtaining thickness data, material sampling was also conducted, followed by physical characterization to identify the type of component material in the pavement layers and their behavioral characteristics.

During this stage, rotary core drilling equipment was used to extract samples, which are typically used in visual assessment of pavement structure. DCP (Dynamic Cone Penetration) was used to determine the degree of compaction of each material layer and its association with apparent density, and test pits were opened at the runway edges to extract material samples for laboratory analysis.

The laboratory analysis consisted of complete material characterization, detailed in Table 3. The subgrade soils were classified following the MCT (Miniature, Compact, Tropical) methodology and categorized as lateritic clayey soil. For granular materials, compaction tests, grain size distribution, and Atterberg limits were performed. For aerodromes A, B, and C, the base layer component material was classified as well-graded crushed stone, while for the subbase layer at aerodromes A and B, the presence of dry-bound macadam was observed, and at aerodrome C, a simple graded crushed stone was found. For the asphalt concrete surface, bitumen extraction, grain size distribution, and Los Angeles abrasion tests were conducted. RT testing was not possible due to the thin layer thickness of approximately 5 cm. The classification resulted in hot-mix dense asphalt concrete with CAP 50/70 binder type.

Based on the material characterization, modulus and Poisson’s ratio values were assigned according to existing literature data for materials within the same classification, since modulus testing was not performed due to the insufficient quantity of extracted material samples. The back-calculated modulus and Poisson’s ratio values are detailed in Table 3. Having determined the homogeneous segmentation of the runways, the component materials of the structures, their moduli, the thickness of each layer composing the runway pavement structures, and the field-measured deflections that were corrected for temperature, the back-calculation process was conducted to obtain the actual modulus values of the layers. The results of the back-calculated module for each pavement layer of the three runways are detailed in Table 4.

Table 4
PCR for back-calculated structures with HMA (CAP 50-70).

AERODROME A
RIGHT LANE-RWY					LEFT LANE-RWY
SEGMENT	LAYER	MATERIALS	BACKANALYZED MODULUS (MPa)	SEGMENT PCR	BACKANALYZED MODULUS (MPa)	SEGMENT PCR
SH-01	Coating	HMA (CAP 50-70)	5,121	600/F/B/X/T	5,518	540/F/A/X/T
	Base	Well graded gravel	999		1,035
	Sub-base	Dry macadam	373		322
	Subgrade	Laterite clay soil	150		158
SH-02	Coating	HMA (CAP 50-70)	5,100	400/F/A/X/T	5,913	480/F/A/X/T
	Base	Well graded gravel	919		828
	Sub-base	Dry macadam	288		229
	Subgrade	Laterite clay soil	151		155
SH-03	Coating	HMA (CAP 50-70)	4,384	350/F/A/X/T	5,263	440/F/A/X/T
	Base	Well graded gravel	283		201
	Sub-base	Dry macadam	95		99
	Subgrade	Laterite clay soil	217*		243*
Runway PCR			440/F/B/X/T
AERODROME B
RIGHT LANE-RWY					LEFT LANE-RWY
SEGMENT	LAYER	MATERIALS	BACKANALYZED MODULUS (MPa)	SEGMENt PCR	BACKANALYZED MODULUS (MPa)	SEGMENT PCR
SH-01	Coating	HMA (CAP 50-70)	3,357	370/F/B/X/T	3,061	380/F/B/X/T
	Base	Well graded gravel	259		232
	Sub-base	Dry macadam	141		124
	Subgrade	Laterite clay soil	135		128
SH-02	Coating	HMA (CAP 50-70)	3,474	470/F/B/X/T	3,344	380/F/B/X/T
	Base	Well graded gravel	354		282
	Sub-base	Dry macadam	207		170
	Subgrade	Laterite clay soil	142		126
SH-03	Coating	HMA (CAP 50-70)	2,799	330/F/B/X/T	2,926	350/F/B/X/T
	Base	Well graded gravel	303		277
	Sub-base	Dry macadam	178		142
	Subgrade	Laterite clay soil	128		112
SH-04	Coating	HMA (CAP 50-70)	2,830	210/F/B/X/T	2,319	230/F/C/X/T
	Base	Well graded gravel	229		164
	Sub-base	Dry macadam	116		115
	Subgrade	Laterite clay soil	107		88
Runway PCR			210/F/B/X/T
AERODROME C
RIGHT LANE-RWY					LEFT LANE-RWY
SEGMENT	LAYER	MATERIALS	BACKANALYZED MODULUS (MPa)	SEGMENT PCR	BACKANALYZED MODULUS (MPa)	SEGMENT PCR
SH-01	Coating	HMA (CAP 50-70)	4,382	460/F/A/X/T	4,234	460/F/A/X/T
	Base	Well graded gravel	237		214
	Sub-base	Plain gravel	137		151
	Subgrade	Laterite clay soil	163		142
SH-02	Coating	HMA (CAP 50-70)	4,041	560/F/A/X/T	5,064	600/F/B/X/T
	Base	Well graded gravel	296		238
	Sub-base	Plain gravel	116		147
	Subgrade	Laterite clay soil	273*		294*
SH-03	Coating	HMA (CAP 50-70)	3,686	380/F/B/X/T	4,543	390/F/B/X/T
	Base	Well graded gravel	236		251
	Sub-base	Plain gravel	148		145
	Subgrade	Laterite clay soil	123		115
SH-04	Coating	HMA (CAP 50-70)	4,305	460/F/A/X/T	4,013	550/F/A/X/T
	Base	Well graded gravel	214		281
	Sub-base	Plain gravel	151		163
	Subgrade	Laterite clay soil	142		219*
Runway PCR			380/F/B/X/T

Analyzing Table 4, it can be observed that after the back-calculation process, segments SH-01 and SH-02 of aerodrome C’s runway exhibited inverted behavior regarding layer hierarchy, where the subgrade soil presented a higher modulus compared to the subbase layer. This condition can be explained by the behavior of lateritic soils, which, despite being composed of fine clayey material, exhibit high concentrations of iron oxides and hydroxides, and aluminum hydroxide as well as clay minerals due to the laterization process. These act as cementing agents, providing the soil with high stability, low plasticity, and excellent mechanical behavior even under saturation conditions.

Analyzing Table 4, it is possible to observe the PCR values calculated for the pavement structures of the three aerodromes in the study. This calculation was performed using FAARFIELD 2.0 software, considering the airport traffic loading detailed in Table 2. For each homogeneous segment, an individual PCR was calculated based on the distinct runway stratifications, and the PCR value of the runway pavement structure was determined as the lowest PCR obtained among the analyzed segments, an adoption made in favor of operational safety. It is worth noting that the numerical values of the PCR refer to the calculation interaction; the letters F or R refer to the surface type, which can be asphalt concrete (flexible) or Portland cement concrete (rigid); the letters A, B, C, and D refer to the subgrade soil strength, which can be high (A), medium (B), low (C), and ultra-low (D); the letters W, X, Y, and Z refer to the tire pressure of the landing gear of the aircraft in the mix, ranging from low (limited to 0.5 MPa) to unlimited with no pressure limit; and the codes T and U refer to the evaluation method, whether it is technical (T) or using aircraft data (U).

4.3. Recycled asphalt mix with RAP incorporation

For the choice of asphalt mixture type, the applicability and analysis criterion adopted was to use a recycled asphalt mixture that would entirely utilize the aggregate material from milling the surface layer of deteriorated pavement structures.

Given the RAP quality, its positive use in new asphalt mixtures, and success in the highway sector [⁴⁰], the analyses used a new surface layer composed of hot-recycled asphalt concrete with 100% RAP.

Because it is a mixture with a high RAP percentage, during the mix design process, it was expected that it would present a high degree of stiffness due to the modification that the remaining binder in the RAP would cause when again subjected to high temperatures and to the homogenization and mixture application process. And considering that resulting from high stiffness, these present low consolidation and rutting indices; however, they tend to have susceptibility to premature fatigue cracking [¹⁰], impacting the integrity and life cycle of the pavement structure.

To minimize oxidation, improve cohesion, and enhance workability, a recycling agent (RA) from shale oil was used. The RA content is directly related to the remaining binder in the RAP and set at 20% of the binder percentage in the reclaimed material [⁶⁶]. This amount is considered enough to provide mixture lubricity and alter the binder, increasing the maltene fraction.

The mix design process followed that recommended by the Superpave methodology, and the physical characterization data of materials and mixture mechanics are detailed in Tables 5–9 and Figure 4, with the materials and mixture being the same studied by [¹⁰].

Table 5
RAP characterization.

RAP CHARACTERIZATION		CHARACTERIZATION OF THE REMAINING AGGREGATE
PARAMETERS	RAP	PARAMETERS	BIG	KID	FÍLLER
Actual specific mass (g/cm3)	2.57	True density (g/cm3)	2.751	2.764	2.692
Apparent specific mass (g/cm3)	2.28	Apparent specific mass (g/cm3)	2.725	2.631	–
Absorption (%)	1.43	Absorption (%)	0.52	0.605	–
Gmm (g/cm3)	1.35	Impact wear Marshall (%) 16.04
Muffle furnace (%)	5.78	Form index 0.645

Table 6
Remaining binder characterization.

CHARACTERIZATION OF THE REMAINING CAP
TEST	METHOD		CAP REMAINING
Penetration (mm)	ASTM D 5		29.4 mm
Softening point (°C)	ASTM D 36		64.1 °C
Flash Point (°C)	ASTM D 92		194.6 °C
Rotational viscosity Brookfield (cP)	ASTM D 4402/15	135°C	600 cP
		150°C	528 cP
		177°C	417 cP
Density (g/cm3)	ASTM D 70		1.14 g/cm3
Ductility (cm)	ASTM D 113		18.6 cm

Table 7
Recycling agent characterization.

CHARACTERIZATION OF THE RECYCLING AGENT
TEST	METHOD		AR-5
Flash Point (°C)	ASTM D 92		318.6 °C
Rotational viscosity Brookfield (cP)	ASTM D 4402 M	60°C	409.78 cP
Density (g/cm3)	ASTM D 70	20ºC	1.18 g/cm3

Table 8
Volumetric parameters of the mixture.

MIXTURE	RESIDUAL BINDER CONTENT (%)	AR CONTENT (%)	Gmb (g/cm3)	Gmm (g/cm3)	VV (%)	VMA (%)	RBV (%)
HMA-R100	0	20	2.332	2.454	4.2	16.25	75.38

Table 9
Mixture asphalt characterization.

MIXTURE	RT (MPa)	WEAR (%)	RRT HIGH SEVERITY	RRT LOW SEVERITY	MODULUS RESILIENT (MPa)
HMA-R100	2.3134	9.11	92.70%	98.50%	11,441.33

Figure 4
Particle size distribution of the mixture.

RAP characterization was carried out regarding its natural state and regarding the waste component materials separately, as listed in Table 5. Black aggregate characterization was performed, and subsequently that of the gray aggregate resulting from the extraction of the oxidized binder by the ignition burn method in a muffle furnace. It should be emphasized that the characterization of the aggregate without binder residue was performed with a view to knowing the existing filler material portion and the residual adhesion and cohesion capacity, to evaluate whether there would be a need for possible gradation corrections and additions of new binders.

RAP characterization, as listed in Table 5, allowed observation of satisfactory indices regarding abrasiveness, aggregate shape, bulk specific gravity, and true grain density, as they fall within the limits recommended by manuals and literature. Regarding RAP aggregate absorption, it presented slightly lower than usual for material retained and passing the 4.36 mm sieve, and for the filler, it was not possible to evaluate, because it has binder and solvent residues incorporated in the material; adhesiveness was not performed for the aggregate in isolation, having been evaluated through deleterious water damage in the asphalt mixture.

The remaining binder characterization process was comprised of conventional tests that seek to obtain parameters such as viscosity, thermal susceptibility, softening point, ductility, and density, as listed in Table 6. And obtaining this oxidized binder occurred through extraction with chlorinated solvent (trichloroethylene) following the centrifugation methodology with rotarex equipment in compliance with NBR 16208 [⁶⁷], with a subsequent recovery stage by the rota-evaporation method prescribed in ASTM D 5404 [⁶⁸].

Analyzing Table 6, it can be observed that the recovered binder, being oxidized, was already expected to present properties distinct from the original ones, highlighting superiority in density parameters, lower penetration rates, having a similarity with CAP 50/70 type binders that have undergone long-term aging [⁶⁹].

Verifying the resulting data from the remaining binder characterization, it is noted from the softening point test that the material presents a more viscous behavior, which is confirmed in the rotational viscosity evaluation, whose obtained values correspond to rates more than 70% higher than a virgin CAP 50/70 type material [²⁷]. Ductility, on the other hand, presented lower than that of a virgin CAP 50/70 type binder due to the material being more rigid because of contamination by chemical solvents and fine material believed to be present in the recovered binder.

Regarding the recycling agent characterization, an agent from the AR-5 class was used, based on shale oil, specifically for applicability in hot-mix asphalt. Analyzing Table 7, it can be observed that the results met the requirements prescribed in Resolution No. 897/22 National Agency of Petroleum, Natural Gas and Biofuels [⁷⁰], and fell within the limits established according to test standards, with flash point and density higher than that of the oxidized binder, having a low viscosity for the 60°C range, ideal for providing better mixture lubricity.

Regarding the asphalt mixture performance, according to the data presented in Figure 4, it is possible to observe from the particle size distribution curve of the HMA-R100 mixture that it fell within gradation No. 01 in compliance with AC 150 5370-10H [⁵⁴], and with the criteria of the Superpave methodology according to AASHTO M 323 standard [⁷¹].

It should also be emphasized that for the designed mixture, despite the existence of the remaining binder portion in the material, RAP was classified as a black aggregate within the recycled mixture, and although particle size correction was not performed, due to total utilization of the material, the mixture curve met the methodology control points and fell within a specific airport gradation. As a consequence of the aggregate having a certain amount of remaining binder, the optimum content corresponded to the residual content present in the reclaimed material, plus the incorporation of the recycling agent in the amount of 20% of the residual binder content, which according to mixture characterization testing, resulted in satisfactory mechanical performance, whose indices of the main analyses are detailed in Tables 8 and 9.

From the data in Table 8, it is possible to note that the mixture presented volumetric parameters within normality for hot-mix asphalt, whether for voids filled with asphalt ratio greater than 65%, air voids in the range of 4%, and voids in mineral aggregate greater than 11% [⁷², ⁷³]. Due to the large amount of mastic in the mixture, and because the aggregate is enveloped by a thin film of oxidized binder and the particle size distribution of the mixture is completely composed of black aggregate, it was observed that when the material was heated, the tendency to agglomerate and generate a cohesive matrix was continuous, which resulted in ease in the compaction and densification process.

Such verification of the mixture densification process is reaffirmed by the data from the indirect tensile strength test presented in Table 9, where the damage caused by the deleterious effect of water on recycled mixtures was much lower than described in manuals and standards [³⁸, ⁷⁴], with damage of 7.3% for high severity and 1.5% for low severity, while up to 20% damage is permitted.

Regarding raveling, the mixture presented raveling considered somewhat higher than conventional mixtures, due to its presenting a portion of high stiffness. Such stiffness was visualized during execution of the indirect tensile strength test, whose obtained value was much higher than what is found in hot-mix asphalt with virgin materials, which typically present ITS slightly greater than 0.65 MPa [²⁷, ⁷²]. While recycled asphalt mixtures present the tendency for higher indirect tensile strength values in proportionality to the reclaimed material incorporation content [²⁸, ²⁹]. This was visualized by the peak strength measured in the ITS and almost no residual strength, leading to the complete disintegration of the specimen after the test.

From the results obtained in the indirect tensile strength test, the resilient modulus test was performed applying a seating stress of 25% of the average ITS obtained in the mixture, whose average resilient modulus value found was greater than 11,000 MPa, a high modulus when compared to conventional mixtures that tend to present values around 1,600 MPa [⁴⁶]. Such behavior was expected because asphalt mixtures with the incorporation of inert material present stiffness gain, have low deformability, which provides higher average moduli.

Consequently, very stiff mixtures tend to have low fatigue life when subjected to loading stresses. For the airport sector, such premature cracking can be characterized as a risk to the sector and especially to operational safety, making it necessary to seek complementary engineering solutions, aiming at the applicability of the technique.

4.4. Redesigning the structure with recycled asphalt concrete surface with RAP

To evaluate the structural capacity gain of the runways of aerodromes A, B, and C, the pavement structure redesign of the aforementioned study runways was sought, replacing the existing surface layer with a hot-mix asphalt concrete surface layer with RAP incorporation, that is, with the HMA R-100 mixture, which contains 100% RAP by mass in its composition.

For estimation of the new PCR in the runway structures with HMA-R100 surface layer, the same loading conditions of existing airport traffic at each aerodrome were adopted, respecting the same number of coverages and the same percentage of operations growth, as described in Table 2, in addition to data on structural layer thicknesses and back-calculated moduli of component materials of granular layers evidenced in Tables 3 and 4.

With a view to adopting the standard procedure for determining the characteristic runway PCR, PCR calculation was performed for each segment obtained in the back-calculation process, considering the layer thicknesses measured in each homogeneous segment, and replacing the conventional asphalt concrete layer with an HMA-R100 mixture surface layer, as detailed in Table 10. The resulting PCRs presented higher than previously calculated values, representing a considerable load-bearing capacity gain.

Table 10
PCR for structure with HMA-R100.

AERODROME A
RIGHT LANE-RWY					LEFT LANE-RWY
SEGMENT	LAYER	MATERIALS	BACKANALYZED MODULUS (MPa)	SEGMENT PCR	BACKANALYZED MODULUS (MPa)	SEGMENT PCR
SH-01	Coating	HMA R-100	11,441	670/F/B/X/T	11,441	730/F/A/X/T
	Base	Well graded gravel	999		1035
	Sub-base	Dry macadam	373		322
	Subgrade	Laterite clay soil	150		158
SH-02	Coating	HMA R-100	11,441	570/F/A/X/T	11,441	650/F/A/X/T
	Base	Well graded gravel	919		828
	Sub-base	Dry macadam	288		229
	Subgrade	Laterite clay soil	151		155
SH-03	Coating	HMA R-100	11,441	430/F/A/X/T	11,441	490/F/A/X/T
	Base	Well graded gravel	283		201
	Sub-base	Dry macadam	95		99
	Subgrade	Laterite clay soil	217*		243*
Runway PCR			670/F/B/X/T
AERODROME B
RIGHT LANE-RWY					LEFT LANE-RWY
SEGMENT	LAYER	MATERIALS	BACKANALYZED MODULUS (MPa)	SEGMENT PCR	BACKANALYZED MODULUS (MPa)	SEGMENT PCR
SH-01	Coating	HMA R-100	11,441	410/F/B/X/T	11,441	420/F/B/X/T
	Base	Well graded gravel	259		232
	Sub-base	Dry macadam	141		124
	Subgrade	Laterite clay soil	135		128
SH-02	Coating	HMA R-100	11,441	510/F/B/X/T	11,441	420/F/B/X/T
	Base	Well graded gravel	354		282
	Sub-base	Dry macadam	207		170
	Subgrade	Laterite clay soil	142		126
SH-03	Coating	HMA R-100	11,441	370/F/B/X/T	11,441	390/F/B/X/T
	Base	Well graded gravel	303		277
	Sub-base	Dry macadam	178		142
	Subgrade	Laterite clay soil	128		112
SH-04	Coating	HMA R-100	11,441	240/F/B/X/T	11,441	260/F/C/X/T
	Base	Well graded gravel	229		164
	Sub-base	Dry macadam	116		115
	Subgrade	Laterite clay soil	107		88
Runway PCR			260/F/C/X/T
AERODROME C
RIGHT LANE-RWY					LEFT LANE-RWY
SEGMENT	LAYER	MATERIALS	BACKANALYZED MODULUS (MPa)	SEGMENT PCR	BACKANALYZED MODULUS (MPa)	SEGMENT PCR
SH-01	Coating	HMA R-100	11,441	540/F/A/X/T	11,441	550/F/A/X/T
	Base	Well graded gravel	237		214
	Sub-base	Plain gravel	137		151
	Subgrade	Laterite clay soil	163		142
SH-02	Coating	HMA R-100	11,441	800/F/A/X/T	11,441	810/F/A/X/T
	Base	Well graded gravel	296		238
	Sub-base	Plain gravel	116		147
	Subgrade	Laterite clay soil	273*		294*
SH-03	Coating	HMA R-100	11,441	470/F/B/X/T	11,441	450/F/B/X/T
	Base	Well graded gravel	236		251
	Sub-base	Plain gravel	148		145
	Subgrade	Laterite clay soil	123		115
SH-04	Coating	HMA R-100	11,441	550/F/A/X/T	11,441	800/F/A/X/T
	Base	Well graded gravel	214		281
	Sub-base	Plain gravel	151		163
	Subgrade	Laterite clay soil	142		219*
Runway PCR			450/F/B/X/T

Analyzing the results, it can be considered that the structural bearing capacity gain occurred due to increased surface layer moduli when replacing the conventional asphalt concrete mixture with a hot-recycled asphalt concrete mixture with the incorporation of high RAP content.

Such justification for the significant gain can be explained by the simple fact that the surface layer, among the others existing in the runway structure, is the layer that is subject to wear at a greater potential due to direct incidence of stresses from the tire pressure of aircraft landing gear, and to wear.

Therefore, given the situation of the same loading, and with asphalt concrete having higher moduli, regarding localized deformations, these tend to be lower due to material stiffness, which would result in the presumption of longer service life for the structure and consequently a functional gain with lower incidences of longitudinal roughness.

However, the performance relationship of structures designed with high-modulus asphalt mixtures is not linear, because although mixtures with higher stiffness result in good rutting behavior, they tend to present reduced fatigue life, that is, premature cracking [¹⁰, ²⁹, ³⁸]. This can be confirmed in the study by [¹⁰], in which, evaluating three types of asphalt mixtures with different RAP percentages in the composition, including the HMAR-100 mixture, they concluded that the higher the reclaimed material content, the lower the structure’s fatigue life would be, considering the same loading conditions.

And in the airport sector, fatigue cracking associated with excess stiffness is a high-potential encumbrance to operations, because due to the stress levels incident on the structure being high, it is necessary that the component material of the pavement layer has the capacity to deform and recover without generating premature material failure. Because premature failure (cracking) associated with stress incidence and absence of elastic recovery of the material can result in detachment of fragments that would put the operation at risk, due to the possible appearance of FOD.

This is the reason that the [⁵³], through circular AC 150/5370-10H, suggests that recycled asphalt mixtures with RAP be applied in binder courses and not in wearing courses, due to the risk of raveling and jet blast events.

However, analyzing the HMA-R100 mixture data in Table 9, it presented raveling of 9.1%, which is following the average raveling in dense asphalt concretes hot-mixed with virgin and conventional materials. Although the Cantabro abrasion test is standardized for analysis of porous asphalt mixtures, such that they present raveling less than 25%, it is possible to perform the test for dense mixtures presenting as good result values less than 10% [⁷⁵]. This indicates that the mixture presents good adhesion and cohesion, confirmed by the retained tensile strength results through moisture damage in the present analysis, whose damages were less than 8% for high severity and less than 2% for low severity.

Therefore, from information on layer thicknesses, characterization of component materials of granular layers and back-calculated resilient moduli of runway pavements of the studied aerodromes, listed in Tables 3 and 4, data processing was performed, which culminated in the generation of typical pavement structures for each runway, with HMA-R100 surface layer and overlay of a thin polymeric seal coat layer, as shown in Figure 5.

Figure 5
Pavement typical sections.

The technique of applying a seal coat over the HMA-R100 asphalt concrete wearing course arises with the premise of sealing the surface layer and ensuring that there is no eventual raveling or detachment of aggregates from the pavement surface when it is under operation.

Because the seal coat is characterized as a surface treatment used in pavement rejuvenation, sealing of surface cracks, increasing friction levels and correcting of small irregularity levels, the material does not present a structural coefficient [⁷⁶]. Therefore, for the present analysis of load-bearing capacity gain by the PCR calculation method, no mechanical performance value was adopted for the seal coat, considering in this situation only the contribution of the HMA-R100 surface layer in replacement of conventional asphalt concrete with CAP 50–70.

5. CONCLUSION

Given the demand for conscious use of natural resources and compliance with goals for mitigating Greenhouse Gas (GHG) emissions, the use of waste from milling the surface layer of deteriorated pavement structures emerges as an economical and sustainable technique in the paving sector. In the highway sector, the use of RAP in the design of new asphalt mixtures is already a reality, due to the longer study time and consequently better acceptance. However, regarding airport pavements, there are still reservations, mainly in relation to operational safety due to the risk of material detachment resulting from stiffening of the resulting mixtures. However, facing environmental challenges, it is necessary to advance investigations so that reliable parameters for RAP use in airport pavements can be found, making these structures resilient in this aspect.

Thus, the present research demonstrated the freasibility and superior mechanical behavior performance in the application of Hot-Recycled Asphalt Concrete with 100% RAP (HMA-R100) as a surface layer in airport pavements. Through backcalculation of the runways of three aerodromes and subsequent redesign, the study demonstrated that asphalt mixtures with RAP incorporation and addition of shale oil-based recycling agent resulted in recycled mixtures whose superior behavior showed higher than the limits of a conventional mixture. The average resilient modulus value of the HMA-R100 mixture found was greater than 11,000 MPa, being significantly high when compared to conventional mixtures, which tend to present values around 1,600 MPa.

Furthermore, the structural redesign results presented a performance gain and PCR increase in all recalculated structures with HMA-R100 surface layer, compared to the backcalculated values of existing structures. This significant increase in bearing capacity is directly attributed to the higher moduli of the recycled surface layer. Although the high stiffness of the HMA-R100 mixture confers good rutting behavior, it can also point to a tendency for low fatigue life and susceptibility to premature cracking. In the airport environment, this premature failure represents a high risk to operational safety due to the potential occurrence of fragment detachment and Foreign Object Damage (FOD), this fact being the main reason for timid RAP use in the sector.

To mitigate the risk of raveling and ensure surface integrity, the possibility of applying a polymeric seal coat over the HMA-R100 layer was raised. This engineering technique aims to seal the surface layer and minimize the risk of aggregate detachment. Tests demonstrated that the HMA-R100 mixture presented acceptable raveling of 9.1% (below the 10% limit for dense mixtures) and low moisture damage (less than 8% for high severity). However, studies still need to be conducted to understand what the bond between the pavement layer and this seal coat layer will be like so that there is no delamination.

Finally, it can be concluded that the study provides some answers regarding the mechanical aspect of mixtures and proposes an investigation into the possibility of using a polymeric seal coat to enable the use of RAP in airport pavements.

6. DATA AVAILABILITY

The dataset supporting the results of this study is not publicly available.

7. BIBLIOGRAPHY

• ^[1] CAVALCANTE, P.H.S., “Avaliação do comportamento estrutural de pavimento aeroportuário com a incorporação de RAP – Reclaimed Asphalt Pavement – como solução para pavimentos asfálticos aeroportuários sustentáveis”, B.Sc. Thesis, Instituto Tecnológico de Aeronáutica, São José dos Campos, 2023.
• ^[2] FERREIRA, A.B., MACHADO, B.V.Z., SALLES, D.C., et al., “Modelagem e regulação de projetos de concessão rodoviária sob a ótica do financiador”, BNDES Setorial, v. 27, n. 54, pp. 7–82, Sep. 2021. http://web.bndes.gov.br/bib/jspui/handle/1408/21524, accessed in July, 2026.
• ^[3] OLIVEIRA, M.S., PELUSI, G.B., BOSCHETTI, R.S., et al., A garantia do controle tecnológico e de qualidade em obras de pavimentação aeroportuária no âmbito da força aérea brasileira, https://www.even3.com.br/xxi-sitraer-2024/, accessed in July, 2026.
  » https://www.even3.com.br/xxi-sitraer-2024
• ^[4] MERIGHI, L.F., OLIVEIRA, M.S., PEREIRA, C.A., et al., Importância do controle de qualidade em obras de pavimentação aeroportuárias https://sitraer2023.joinville.ufsc.br/, accessed in July, 2026.
  » https://sitraer2023.joinville.ufsc.br
• ^[5] AGÊNCIA NACIONAL DE AVIAÇÃO CIVIL, Dados estatísticos do transporte aéreo, 2023. https://www.anac.gov.br/acesso-a-informacao/dados-abertos/areas-de-atuacao/voos-eoperacoes-aereas/dados-estatisticos-do-transporte-aereo, accessed in October, 2025.
  » https://www.anac.gov.br/acesso-a-informacao/dados-abertos/areas-de-atuacao/voos-eoperacoes-aereas/dados-estatisticos-do-transporte-aereo
• ^[6] OLIVEIRA, M.S., PEREIRA, C.A., DE ASSIS FARIAS, P.C., “Applicability of PAVEAIR for airport pavement management: comparison between military and civilian runways”, Journal of Civil Engineering and Architecture, v. 14, n. 7, pp. 360–367, 2020. doi: https://doi.org/10.17265/1934-7359/2020.07.002.
  » https://doi.org/10.17265/1934-7359/2020.07.002
• ^[7] SUZUKI, K., VASCONCELOS, K., KLINSKY, L.M., et al., “Evaluation of recycled asphalt mixtures with different RAP contents and the effect of recycling agent”, Road Materials and Pavement Design, v. 25, pp. 124–136, 2023. doi: https://doi.org/10.1080/14680629.2023.2191739.
  » https://doi.org/10.1080/14680629.2023.2191739
• ^[8] PINHEIRO, G., VASCONCELOS, K., BERNUCCI, L., “Reclaimed asphalt pavement binder extraction and recovery evaluation and their effects on the recycling agent assessment”, Transportation Research Record: Journal of the Transportation Research Board, v. 2676, n. 11, pp. 707–721, 2022. doi: https://doi.org/10.1177/03611981221094567.
  » https://doi.org/10.1177/03611981221094567
• ^[9] OLIVEIRA, J.R.M., SILVA, H.M.R.D., ABREU, L.P.F., et al., “Effect of different production conditions on the quality of hot recycled asphalt mixtures”, Procedia: Social and Behavioral Sciences, v. 53, n. 3, pp. 266–275, 2012. doi: https://doi.org/10.1016/j.sbspro.2012.09.879.
  » https://doi.org/10.1016/j.sbspro.2012.09.879
• ^[10] OLIVEIRA, M.S., FARIAS, M.M., “Hot recycled asphalt mixtures with the incorporation of milled material: analysis of the mechanical performance and economic presumption in the applicability of the technique”, Matéria, v. 27, n. 4, 2022. doi: https://doi.org/10.1590/1517-7076-rmat-2022-0217.
  » https://doi.org/10.1590/1517-7076-rmat-2022-0217
• ^[11] PINSKY, V.C., GOMES, C.M., KRUGLIANSKAS, I., “Metas brasileiras no Acordo de Paris: reflexões sobre o papel das universidades”, Revista de Gestão Ambiental e Sustentabilidade, v. 8, n. 2, pp. 335–362, 2019. doi: https://doi.org/10.5585/geas.v8i2.11229.
  » https://doi.org/10.5585/geas.v8i2.11229
• ^[12] BRASIL, Ministério dos Transportes, “Portaria nº 622 de 28 junho de 2024. Diretrizes para alocação de recursos em contratos de concessão rodoviária federais visando ao desenvolvimento de infraestrutura resiliente”, Diário Oficial da União, 2024. https://www.in.gov.br/en/web/dou/-/portaria-n-622-de-28-de-junho-de-2024-569046197, accessed in November, 2024.
  » https://www.in.gov.br/en/web/dou/-/portaria-n-622-de-28-de-junho-de-2024-569046197
• ^[13] MARIA, C., NASCIMENTO, V., “A influência da vulnerabilidade climática no comportamento de países do G20 em relação ao Acordo de Paris”, Conjuntura Austral, v. 14, n. 65, pp. 61–74, 2023. doi: https://doi.org/10.22456/2178-8839.129165.
  » https://doi.org/10.22456/2178-8839.129165
• ^[14] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS, ABNT NBR ISO 14020 (2025) Declarações e programas ambientais de produtos — Princípios e requisitos gerais, Rio de Janeiro, ABNT, 2025.
• ^[15] RANGELOV, M., DYLLA, H., SIVANESWARAN, N., “Environmental product declarations (EPDs)/product category rules (PCRs) of waste plastics and recycled materials in roads”, In: Giustozzi, F., Nizamuddin, S. (eds), Plastic waste for sustainable asphalt roads, Sawston, Woodhead Publishing, pp. 303–334, 2022. doi: https://doi.org/10.1016/B978-0-323-85789-5.00015-0.
  » https://doi.org/10.1016/B978-0-323-85789-5.00015-0
• ^[16] OLIVEIRA, M.S., FARIAS, M.M., SILVA, J.P.S., “Fatigue analysis of hot recycled asphalt mixtures with RAP incorporation”, Case Studies in Construction Materials, v. 16, pp. e01132, 2022. doi: https://doi.org/10.1016/j.cscm.2022.e01132.
  » https://doi.org/10.1016/j.cscm.2022.e01132
• ^[17] MASCARENHAS, Z.G., PIAO, Z., VASCONCELOS, K.L., et al., “Comparative environmental analysis of pavement structures with recycled asphalt mixtures produced in Brazil and in Switzerland”, SSRN, 2022. doi: https://doi.org/10.2139/ssrn.4189363.
  » https://doi.org/10.2139/ssrn.4189363
• ^[18] MELO NETO, O.D.M.M., SILVA, I.M., LUCENA, L.C.D.F.L., et al., “Viability of recycled asphalt mixtures with soybean oil sludge fatty acid”, Construction & Building Materials, v. 349, pp. 128728, 2022. doi: https://doi.org/10.1016/j.conbuildmat.2022.128728.
  » https://doi.org/10.1016/j.conbuildmat.2022.128728
• ^[19] SAEED, A., TINGLE, J., WILLIAMS JUNIOR, C.E., “Optimized strategies for reducing greenhouse gas emissions during flexible pavement life cycle”, In:International Conference on Transportation and Development, Atlanta, Georgia, 15–18 June 2024. doi: https://doi.org/10.1061/9780784485538.004.
  » https://doi.org/10.1061/9780784485538.004
• ^[20] FERREIRA, J.W.S., MARROQUIN, J.F.R., FELIX, J.F., et al., “The feasibility of recycled micro polyethylene terephthalate (PET) replacing natural sand in hot-mix asphalt”, Construction & Building Materials, v. 330, pp. 127276, 2022. doi: https://doi.org/10.1016/j.conbuildmat.2022.127276.
  » https://doi.org/10.1016/j.conbuildmat.2022.127276
• ^[21] BONOLI, A., DEGLI ESPOSTI, A., MAGRINI, C., “A case study of industrial symbiosis to reduce GHG emissions: performance analysis and LCA of asphalt concretes made with RAP aggregates and steel slags”, Frontiers in Materials, v. 7, pp. 572955, 2020. doi: https://doi.org/10.3389/fmats.2020.572955.
  » https://doi.org/10.3389/fmats.2020.572955
• ^[22] BIZARRO, D.E.G., STEINMANN, Z., NIEUWENHUIJSE, I., et al., “Potential carbon footprint reduction for reclaimed asphalt pavement innovations: LCA methodology, best available technology, and near-future reduction potential”, Sustainability, v. 13, n. 3, pp. 1382, 2021. doi: https://doi.org/10.3390/su13031382.
  » https://doi.org/10.3390/su13031382
• ^[23] VIDAL, R., MOLINER, E., MARTINEZ, G., et al., “Life cycle assessment of hot mix asphalt and zeolite-based warm mix asphalt with reclaimed asphalt pavement”, Resources, Conservation and Recycling, v. 74, pp. 101–114, 2013. doi: https://doi.org/10.1016/j.resconrec.2013.02.018.
  » https://doi.org/10.1016/j.resconrec.2013.02.018
• ^[24] AURANGZEB, Q., AL-QADI, I.L., OZER, H., et al., “Hybrid life cycle assessment for asphalt mixtures with high RAP content”, Resources, Conservation and Recycling, v. 83, pp. 77–86, 2014. doi: https://doi.org/10.1016/j.resconrec.2013.12.004.
  » https://doi.org/10.1016/j.resconrec.2013.12.004
• ^[25] LU, Y., WU, H., LIU, A., et al., “Energy consumption and Greenhouse Gas Emissions of high RAP central plant hot recycling technology using Life Cycle Assessment: Case study”, In: Al-Qadi, I.L., Ozer, H., Harvey, J. (eds) Pavement life-cycle assessment, London, CRC Press, pp. 281–290, 2017. doi: https://doi.org/10.1201/9781315159324.
  » https://doi.org/10.1201/9781315159324
• ^[26] SAEEDZADEH, R., ROMANOSCHI, S.A., AKBARIYEH, N., et al., “Sustainability assessment of recycled asphalt mixtures based on performance in full-scale testing”, Journal of Transportation Engineering. Part B, Pavements, v. 144, n. 2, pp. 04018024, 2018. doi: https://doi.org/10.1061/JPEODX.0000048.
  » https://doi.org/10.1061/JPEODX.0000048
• ^[27] BERNUCCI, L.B., MOTTA, L.M.G., CERATTI, J.A.P., et al., Pavimentação asfáltica: formação básica para engenheiros, 2 ed, Rio de Janeiro, PETROBRAS, 2022.
• ^[28] CENTOFANTE, R., SPECHT, L.P., ALMEIDA JUNIOR, P.O.B., et al., “Avaliação do comportamento de misturas asfálticas recicladas a quente com inserção de material fresado”, Matéria, v. 23, n. 3, pp. 1–19, 2018. doi: https://doi.org/10.1590/s1517-707620180003.0512.
  » https://doi.org/10.1590/s1517-707620180003.0512
• ^[29] SUZUKI, K., “Avaliação do percentual de material fresado em misturas asfálticas recicladas à quente e aplicação em projetos de restauração de pavimentos”, Tese de M.Sc., Escola Politécnica, Universidade de São Paulo, São Paulo, SP, 2019.
• ^[30] NAISHENG, G.U.O., YOU, Z., ZHAO, Y., et al., “Laboratory performance of warm mix asphalt containing recycled asphalt mixtures”, Construction & Building Materials, v. 64, pp. 141–149, 2014. doi: https://doi.org/10.1016/j.conbuildmat.2014.04.002.
  » https://doi.org/10.1016/j.conbuildmat.2014.04.002
• ^[31] SONG, W., HUANG, B., SHU, X., “Influence of warm-mix asphalt technology and rejuvenator on performance of asphalt mixtures containing 50% reclaimed asphalt pavement”, Journal of Cleaner Production, v. 192, pp. 191–198, 2018. doi: https://doi.org/10.1016/j.jclepro.2018.04.269.
  » https://doi.org/10.1016/j.jclepro.2018.04.269
• ^[32] XIANGDAO, H.O.U., XIAO, F., WANG, J., et al, “Identification of asphalt aging characterization by spectrophotometry technique”, Fuel, v. 226, pp. 230–239, 2018. doi: https://doi.org/10.1016/j.fuel.2018.04.030.
  » https://doi.org/10.1016/j.fuel.2018.04.030
• ^[33] ZHAO, S., HUANG, B., SHU, X., et al., “Comparative evaluation of warm mix asphalt containing high percentages of reclaimed asphalt pavement”, Construction & Building Materials, v. 44, pp. 92–100, 2013. doi: https://doi.org/10.1016/j.conbuildmat.2013.03.010.
  » https://doi.org/10.1016/j.conbuildmat.2013.03.010
• ^[34] PRADYUMNA, T.A., MITTAL, A., JAIN, P.K., “Characterization of Reclaimed Asphalt Pavement (RAP) for use in bituminous road construction”, Procedia: Social and Behavioral Sciences, v. 104, pp. 1149–1157, 2013. doi: https://doi.org/10.1016/j.sbspro.2013.11.211.
  » https://doi.org/10.1016/j.sbspro.2013.11.211
• ^[35] VASCONCELOS, K.L., Reciclagem a quente/morna de misturas asfálticas – Desafios e perspectivas, 2020. https://drive.google.com/drive/folders/1aXe1G8LO2hdysjjdvbaCfyZAxbZaYlSn, accessed in June, 2020.
  » https://drive.google.com/drive/folders/1aXe1G8LO2hdysjjdvbaCfyZAxbZaYlSn
• ^[36] ZHANG, H., XIE, Q., DING, H., et al., “Effects of physical hardening on low-temperature properties of asphalt binders containing reclaimed asphalt pavement”, Journal of Testing and Evaluation, v. 51, n. 2, pp. 655–672, 2023. doi: https://doi.org/10.1520/JTE20220317.
  » https://doi.org/10.1520/JTE20220317
• ^[37] LUZ, P.M.S.G., SILVA, I.M., MELO NETO, O.D.M., et al., “Analysis of the degree of blending (DoB) of recycled asphalt mixtures with variation in mixing temperature, type, and RAP content”, Construction & Building Materials, v. 431, pp. 136577, 2024. doi: https://doi.org/10.1016/j.conbuildmat.2024.136577.
  » https://doi.org/10.1016/j.conbuildmat.2024.136577
• ^[38] BOHN, K.A.A., SPECHT, L.P., BRONDANI, C., et al., “Avaliação de misturas asfálticas recicladas mornas com uso de ligantes convencional e modificado por polímero”, Transportes, v. 28, n. 1, pp. 18–32, 2020. doi: https://doi.org/10.14295/transportes.v27i4.1740.
  » https://doi.org/10.14295/transportes.v27i4.1740
• ^[39] LUZZI, F.C., SPECHT, L.P., SCHUSTER, S.L., et al., “Adaptação de usina para reciclagem à quente e avaliação laboratorial das misturas asfálticas produzidas”, Revista Ibero-americana de Ciências Ambientais, v. 12, n. 3, pp. 362–382, 2021. doi: https://doi.org/10.6008/CBPC2179-6858.2021.003.0030.
  » https://doi.org/10.6008/CBPC2179-6858.2021.003.0030
• ^[40] MONTEIRO, A.M.C., SILVA, J.P.S., REZENDE, L.R., “Estudo laboratorial de misturas asfálticas recicladas à quente com diferentes teores de asfalto fresado”, Transportes, v. 31, n. 1, pp. 2771, 2023. doi: https://doi.org/10.58922/transportes.v31i1.2771.
  » https://doi.org/10.58922/transportes.v31i1.2771
• ^[41] ZAUMANIS, M., MALLICK, R.B., FRANK, R., “Evaluation of different recycling agents for restoring aged asphalt binder and performance of 100 % recycled asphalt”, Materials and Structures, v. 48, n. 8, pp. 2475–2488, 2015. doi: https://doi.org/10.1617/s11527-014-0332-5.
  » https://doi.org/10.1617/s11527-014-0332-5
• ^[42] ZHANG, W., TANG, J., DONG, Z., et al., “Performance characterization of recycled-asphalt pavement with stabilized rubber–modified asphalt using balanced mix design method”, Journal of Materials in Civil Engineering, v. 32, n. 12, pp. 04020387, Dec. 2020. doi: https://doi.org/10.1061/(ASCE)MT.1943-5533.0003486.
  » https://doi.org/10.1061/(ASCE)MT.1943-5533.0003486
• ^[43] COSTA, D.B., MELO NETO, O.D.M., LUCENA, L.C.D.F.L., et al., “Effects of recycling agents and methods on the fracture and moisture resistance of asphalt mixtures with high RAP contents”, Construction & Building Materials, v. 367, pp. 130312, 2023. doi: https://doi.org/10.1016/j.conbuildmat.2023.130312.
  » https://doi.org/10.1016/j.conbuildmat.2023.130312
• ^[44] COSTA, D.B., MELO NETO, O.M., LUZ, P.M.S.G., et al., “Influence of aging, RAP content, and recycling agent on the performance of asphalt mixtures”, Environmental Science and Pollution Research International, v. 31, n. 1, pp. 1419–1441, 2024. doi: https://doi.org/10.1007/s11356-023-31263-4. PMid:38040884.
  » https://doi.org/10.1007/s11356-023-31263-4
• ^[45] MELO NETO, O.M., SILVA, I.M., LOPES, L.F., “Physical and rheological study of asphalt binders with soybean oil sludge and soybean oil sludge fatty acid”, Waste and Biomass Valorization, v. 14, n. 6, pp. 1945–1967, 2023. doi: https://doi.org/10.1007/s12649-022-01951-2.
  » https://doi.org/10.1007/s12649-022-01951-2
• ^[46] ZUBARAN, M., “Avaliação do comportamento de misturas asfálticas recicladas mornas em laboratório e usina de asfalto”, Tese de M.Sc., Universidade Federal do Rio de Janeiro, Rio de Janeiro, 2014.
• ^[47] OLIVEIRA, M.S., “Análise da fadiga em misturas asfálticas recicladas a quente”, Tese de M.Sc., Departamento de Engenharia Civil e Ambiental, Universidade de Brasília, Brasília, 2020.
• ^[48] DONATO, M.G., GOUVEIA, B.G., MEDEIROS, A.S., et al., “Mechanical analysis of subgrades of road pavements in life cycle assessment”, Civil Engineering Journal-Tehran, v. 8, n. 7, pp. 1492–1506, 2022. doi: https://doi.org/10.28991/CEJ-2022-08-07-012.
  » https://doi.org/10.28991/CEJ-2022-08-07-012
• ^[49] RODRIGUES, R.M., Parte I- Projeto de Pavimentos, São José dos Campos, Instituto Tecnológico de Aeronáutica, 2022.
• ^[50] OLIVEIRA, M.S., PEREIRA, C.A., “Influence of asphalt surface textures on achieving skid resistance levels”, Matéria, v. 30, pp. e20240737, 2025. doi: https://doi.org/10.1590/1517-7076-rmat-2024-0737.
  » https://doi.org/10.1590/1517-7076-rmat-2024-0737
• ^[51] ARAÚJO, J.L., “Características funcionais e mecânicas de misturas asfálticas para revestimento de pavimentos aeroportuários”, Tese de M.Sc., Faculdade de Tecnologia, Departamento de Engenharia Civil, Universidade de Brasília, Brasília, 2009.
• ^[52] RODRIGUES, R.M., Parte II- Ger^encia de Pavimentos, São José dos Campos, Instituto Tecnológico de Aeronáutica, 2022.
• ^[53] DE SALLES, L.S., BALBO, J.T., PEREIRA, D.S., “Avaliação estrutural de pavimento de concreto continuamente armado de curta extensão para corredores de ônibus”, Transportes, v. 23, n. 2, pp. 65–74, 2015. doi: https://doi.org/10.14295/transportes.v23i2.835.
  » https://doi.org/10.14295/transportes.v23i2.835
• ^[54] FEDERAL AVIATION ADMINISTRATION, Advisory Circular 150/5370-10H: Standards for Specifying Construction of Airports, Washington, U.S. Department of Transportation Federal Aviation Administration, 2018.
• ^[55] WHITE, G., “Quantifying the impact of reclaimed asphalt pavement on airport asphalt surfaces”, Construction & Building Materials, v. 197, pp. 757–765, 2018. doi: https://doi.org/10.1016/j.conbuildmat.2018.11.131.
  » https://doi.org/10.1016/j.conbuildmat.2018.11.131
• ^[56] PLUG, C.P., BONDT, A.H., BIJLEVELD, G., et al., Polymer modified bitumen for runways containing 60% recycled asphalt https://www.researchgate.net/publication/359711313, accessed in August, 2025.
  » https://www.researchgate.net/publication/359711313
• ^[57] FEDERAL AVIATION ADMINISTRATION, Advisory Circular 150/5335-5D: Standardized Method of Reporting Airport Pavement Strength – PCR, Washington, U.S. Department of Transportation Federal Aviation Administration, 2022.
• ^[58] ALVES, R.M., PEREIRA, C.A., SCHIAVON, J.A., Comparação entre os Métodos de Classificação de Resistência de Pavimentos Aeroportuários ACN-PCN e ACR-PCR, São José dos Campos, Instituto Tecnológico de Aeronáutica, 2022. https://www.sitraer.ita.br/sitraer2022/Proceedings/proceedings.html, accessed in August, 2025.
  » https://www.sitraer.ita.br/sitraer2022/Proceedings/proceedings.html
• ^[59] AGÊNCIA NACIONAL DE AVIAÇÃO CIVIL, Manual para o Cálculo de PCRdDe Pavimentos Aeroportuários, 2022. https://www.gov.br/anac/pt-br/centrais-de-conteudo/aeroportos-e-aerodromos/manuais-e-cartilhas/manual-de-calculo-de-pcr-de-pavimentos-aeroportuarios/view, accessed in October, 2025.
  » https://www.gov.br/anac/pt-br/centrais-de-conteudo/aeroportos-e-aerodromos/manuais-e-cartilhas/manual-de-calculo-de-pcr-de-pavimentos-aeroportuarios/view
• ^[60] AGÊNCIA NACIONAL DE AVIAÇÃO CIVIL, Instrução Suplementar nº 153.205-001 – Revisão C. Monitoramento da irregularidade longitudinal, atrito e macrotextura do pavimento da pista pouso e decolagem, 2023. https://www.anac.gov.br/assuntos/legislacao/legislacao-1/iac-e-is/is/is-153-205-001, accessed in October, 2024.
  » https://www.anac.gov.br/assuntos/legislacao/legislacao-1/iac-e-is/is/is-153-205-001
• ^[61] FEDERAL AVIATION ADMINISTRATION, Advisory Circular 150/5320-6G: Airport Pavement Design and Evaluation, Washington, U.S. Department of Transportation Federal Aviation Administration, 2021.
• ^[62] BUENO, L.D., “Avaliação deflectométrica e de rigidez: Estudo de caso em três trechos monitorados em Santa Maria/RS”, Tese de M.Sc., Universidade Federal de Santa Maria, Santa Maria, 2016.
• ^[63] BUENO, L.D., PEREIRA, D.S., SPECHT, L.P., et al., “Retroanálise de módulos de resiliência: Aspectos inerentes ao processo iterativo de ajuste de bacias deflectométricas”, Revista de Ciências Exatas Aplicadas e Tecnológicas da UPF, v. 12, pp. 36–50, 2020.
• ^[64] BOETTCHER, A.C., “Avaliação estrutural de pavimentos asfálticos a partir de modelos de elementos finitos estáticos e dinâmicos para simular as medidas das bacias deflectométricas do ensaio FWD”, Tese de M.Sc., Universidade do Estado de Santa Catarina, Joinville, 2023. https://repositorio.udesc.br/handle/UDESC/17282, accessed in July, 2025.
  » https://repositorio.udesc.br/handle/UDESC/17282
• ^[65] FEDERAL AVIATION ADMINISTRATION, Advisory Circular 150/5370-11B: Use of Nondestructive Testing in the Evaluation of Airport Pavements, Washington, U.S. Department of Transportation Federal Aviation Administration, 2011.
• ^[66] SILVA, J.P.S., DE FARIAS, M.M., “Estudo dos efeitos de produtos rejuvenescedores no comportamento físico, químico e reológico de ligante asfáltico envelhecido”, Transportes, v. 28, n. 3, pp. 91–102, 2020. doi: https://doi.org/10.14295/transportes.v28i3.1874.
  » https://doi.org/10.14295/transportes.v28i3.1874
• ^[67] ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS, ABNT NBR 16208 (2023) Misturas asfálticas – Determinação do teor de betume pelo Soxhlet, pelo Rotarex e pelo refluxo duplo, Rio de Janeiro, ABNT, 2013.
• ^[68] AMERICAN SOCIETY FOR TESTING AND MATERIALS, ASTM D5404-24 Standard Practice for Recovery of Asphalt from Solution Using the Rotary Evaporator, West Conshohocken, ASTM, 2024.
• ^[69] CHEN, Z., YU, T., ZHAO, F., et al., “Research on atmospheric components aging behavior of asphalt binders based on multi-scale analysis”, Construction & Building Materials, v. 485, pp. 141948, 2025. doi: https://doi.org/10.1016/j.conbuildmat.2025.141948.
  » https://doi.org/10.1016/j.conbuildmat.2025.141948
• ^[70] AGÊNCIA NACIONAL DE PETRÓLEO, Resolução nº 897, de 18 de novembro de 2022, Brasília, ANP, 2022.
• ^[71] AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS, AASHTO M 323: Standard specification for superpave volumetric mix design, Washington, AASHTO, 2022.
• ^[72] DEPARTAMENTO NACIONAL DE INFRAESTRUTURA DE TRANSPORTES, DNIT 031-ES – Concreto asfáltico. Pavimentação Concreto Asfáltico – Especificação de serviço, Brasília, DNIT, 2024.
• ^[73] DEPARTAMENTO NACIONAL DE INFRAESTRUTURA DE TRANSPORTES, DNIT 449 – PRO: Pavimentação asfáltica – Misturas asfálticas – Parâmetros volumétricos para dosagem de misturas asfálticas – Procedimento, Brasília, DNIT, 2024.
• ^[74] HICKS, R.G., Moisture damage in asphalt concrete, Washington, Transportation Research Board, 1991.
• ^[75] DEPARTAMENTO NACIONAL DE ESTRADAS DE RODAGEM, DNER 383 – ME: Desgaste por abrasão de misturas betuminosas com asfalto polímero – ensaio Cantabro– Método de ensaio, Rio de Janeiro, DNER, 1999.
• ^[76] CERATTI, J.A.P., DE REIS, R.M.M., Manual de microrrevestimento asfaltico a frio, São Paulo, Oficina de Textos, 2011.

Publication Dates

• Publication in this collection
  14 Aug 2026
• Date of issue
  2026

History

• Received
  27 May 2026
• Accepted
  08 July 2026