Bituminous Surface Treatment Research Articles

Effect of Simultaneous Application of Glass Fiber Reinforcement and Polymer-Modified Asphalt Emulsion on DBST’s Resistance to Aggregate Loss Using Laboratory Investigation

Double bituminous surface treatment (DBST) has been a widely utilized pavement maintenance material due to its capability to restore the surface roughness of existing pavement and provide a layer of protection against weathering, aging, and moisture. However, DBST is highly prone to aggregate loss at an early stage, which is a very common problem experienced by surface treatment. Therefore, to lessen the aggregate loss and prolong the service life of DBST, fiber additive can be incorporated to strengthen the adhesion between the asphalt emulsion and aggregates. This study investigated the performance of glass fiber-reinforced polymer-modified DBST against aggregate loss by conducting laboratory tests using typical DBST as the benchmark of the test results. Four laboratory tests were chosen to represent different loading applications on the surface of the pavement: the bitumen bond strength (BBS) test, the sweep test, the Hamburg wheel-track test (HWT test), and a one-third-scale model mobile load simulator (MMLS3) model. Furthermore, the curing time of the asphalt emulsion was considered in the BBS test and sweep test. Based on all results from the conducted laboratory tests, polymer-modified DBST with glass fiber reinforcement presented an increased resistance to aggregate loss compared with typical DBST. Moreover, it was found that a longer curing time of the asphalt emulsion, whether it was typical or modified, strengthened the surface treatment’s resistance to aggregate loss.

Performance Evaluation on the Application of MAST and RCC on a Cambodian Rural Road: A Case Study

Cambodia’s transportation sector has exhibited tremendous growth in the past decades together with its economic advancement. However, these improvements are only focused on the national and provincial roads, leaving the rural roads underdeveloped. A large percentage of the rural roads in Cambodia are unpaved while those paved roads are in deteriorated condition, making these rural roads prone to structural failure when subjected to heavy truck traffic and massive rainfall. Therefore, an innovative pavement material shall be used in the construction and rehabilitation of Cambodian rural roads. In this study, a composite pavement testbed consisting of a roller compacted cement (RCC) base layer and a modified double bituminous surface treatment (DBST), namely multi-layered bituminous surface treatment (MAST), was constructed in Cambodia and its performance was evaluated. To have a point of comparison, the testbed was divided into three sections with varying combinations of surface and base layer: (1) MAST surface with an RCC base, (2) MAST surface with an aggregate base, and (3) DBST surface with an aggregate base. Initially, a visual inspection was conducted to investigate the surface condition of the testbed. To assess the structural capacity, a light-falling weight deflectometer device was used. Meanwhile, the surface roughness was evaluated through the sand patch test. Lastly, the pass-by test was performed to quantify the noise level of the pavement. Based on the results, the proposed composite pavement performed significantly superior to the typical pavement in Cambodia, which is the third section. In summary, the composite pavement with MAST as the surface layer and RCC as the base layer was observed to be suitable for heavy truck traffic loading and the environmental conditions of Cambodia.

Investigation of Cold Recycling of Bituminous Surface Treatment with Foam Bitumen

The course of turned of bituminous pavement layers into hot mix asphalt (HMA) layers has been increasing day by day all over the world. Bituminous surface treatment that contains consirable amount of aggregate and bitumen, is an important source of recycling that offers a great amount of pavement materials intead of virgin material usage on pavement consruction. In the study, it was aimed to investigate the usability of bituminous surface layer treatment in the base layers of the HMA roads by mixing with foam bitumen and active filler materials in order to eliminate the potential performance degradation that will be encountered when it is recycled due to the low bitumen percentage compared to hot mix asphalt and the wear of the aggregate due to climatic conditions and traffic loads over time. The study conducted that intends to technically evaluate the cold recycling of bituminous surface treatment of roads with foam bitumen and active filler materials; for 70/100 bitumen grade, 5 different bitumen mixes were prepared and ideal bitumen percentage was investigated for this bitumen grade. The effect of bitumen percentage on mixture performance was evaluated with 50/70-100/150-160/220 bitumen grades and mixtures were prepared in single bitumen ratio (2.5%). It was investigated that active fillers will give suitable results for foam bituminous mixtures by preparing mixtures for three different active fillers; cement, hydrated lime and fly ash. To evaluate all these productions, ITS, unconfined compressive strenght, triaxial resilient modulus and asphalt permanent deformation tests were performed. The results obtained showed that production made using 2% foam bitumen and 1% was found suitable for moisture sensitivity and structural stability. Recycling of bituminous surface treatment using foam bitumen and cement is an environmentally and economically beneficial method by reducing both waste and raw material consumption.

Application of Adaptive Neuro–Fuzzy Inference System for Forecasting Pavement Roughness in Laos

Laos Pavement Management System (PMS) manages 7700 km of National Roads (NRs) and estimates their Maintenance and Rehabilitation (MR) needs based on assessing pavement roughness conditions. This research aims to develop two International Roughness Index (IRI) models for Double Bituminous Surface Treatment (DBST) and Asphalt Concrete (AC) pavement sections using Adaptive Neuro-Fuzzy Inference System (ANFIS). A historical database of 14 years was employed for predicting the IRI as a function of pavement age and Cumulative Equivalent Single-Axle Load (CESAL). The optimum ANFIS structure comprises a hybrid learning algorithm with six fuzzy rules of generalized bell curve membership functions (Gbellmf) for the DBST model and nine fuzzy rules of two-sided Gaussian membership functions (Gauss2mf) for the AC model. Both models used the constant membership function for the output variable (IRI). The statistical evaluation results revealed that both ANFIS models (DBST and AC) have a good prediction capacity with high values of coefficient of determination (R2 0.93 and 0.88) and low values of Mean Absolute Error (MAE 0.28 and 0.27) and Root Mean Squared Percentage Error (RMSPE 7.03 and 9.98). In addition, results revealed that ANFIS models yielded higher prediction accuracy than Multiple Linear Regression (MLR) models previously developed under the same conditions.

MODELING OF PAVEMENT ROUGHNESS UTILIZING ARTIFICIAL NEURAL NETWORK APPROACH FOR LAOS NATIONAL ROAD NETWORK

The International Roughness Index (IRI) has become the reference scale for assessing pavement roughness in many highway agencies worldwide. This research aims to develop two Artificial Neural Network (ANN) models for Double Bituminous Surface Treatment (DBST) and Asphalt Concrete (AC) pavement sections using Laos Pavement Management System (PMS) database for National Road Network (NRN). The final database consisted of 269 and 122 observations covering 1850 km of DBST NRN and 718 km of AC NRN, respectively. The proposed models predict IRI as a function of pavement age and Cumulative Equivalent Single-Axle Load (CESAL). The obtained data were randomly divided into training (70%), validation (15%), and testing (15%) datasets. The statistical evaluation results of the training dataset reveal that both ANN models (DBST and AC) have good prediction ability with high values of coefficient of determination (R2 = 0.96 and 0.94) and low values of Mean Absolute Error (MAE = 0.23 and 0.19) and Mean Squared Percentage Error (RMSPE = 7.03 and 9.98). Eventually, the goodness of fit of the proposed ANN models was compared with the Multiple Linear Regression (MLR) models previously developed under the same conditions. The results show that ANN models yielded higher prediction accuracy than MLR models.

MONITORING PERFORMANCE OF LATERITE BASE TRIAL SECTION: A CASE OF ADDIS ABABA, ETHIOPIA

This paper is aimed to present an overview of the provision of a demonstration/research trials with particular reference to pavement performance of a laterite base under a double bituminous surface treatment (DBST) as part of a long-term pavement performance (LTPP) monitoring in Ethiopia. The research components were aimed at increasing the use of locally available materials and solving specific problems related to the performance of some roads constructed with thin asphalt seals. In Ethiopia, most roads are built using crushed rock for road base. The project aim was to demonstrate that whether laterite can be used for base course, assess and evaluate the effect of sealed and unsealed shoulder in cut and fill sections. Out of the various field data measurements carried out in each monitoring period (wet and dry season) the paper reviews the in-situ dynamic cone penetrometer (DCP) test results and visual condition assessment observations. It is demonstrated that for such low volume roads laterite base trial sections are performing well, however DCP test results in these sections reveals that the crushed base control sections perform slightly better than the laterite base trial sections and the sections in cut are stronger than in fill while the shoulder sealing doesn’t provide consistent effect on the layer strengths.

Development of Roughness Prediction Models for Laos National Road Network

The International Roughness Index (IRI) has been accepted globally as an essential indicator for assessing pavement condition. The Laos Road Management System (RMS) utilizes a default Highway Development and Management (HDM-4) IRI prediction model. However, developed IRI values have shown the need to calibrate the IRI prediction model. Data records are not fully available for Laos yet, making it difficult to calibrate IRI for the local conditions. This paper aims to develop an IRI prediction model for the National Road Network (NRN) based on the available Laos RMS database. The Multiple Linear Regression (MLR) analysis technique was applied to develop two new IRI prediction models for Double Bituminous Surface Treatment (DBST) and Asphalt Concrete (AC) pavement sections. The final database consisted of 83 sections with 269 observations over a 1850 km length of DBST NRN and 29 sections with 122 observations over a 718 km length of AC NRN. The proposed models predict IRI as a function of pavement age and Cumulative Equivalent Single-Axle Load (CESAL). The model’s parameter analysis confirmed their significance, and R2 values were 0.89 and 0.84 for DBST and AC models, respectively. It can be concluded that the developed models can serve as a useful tool for engineers maintaining paved NRN.

Avaliação da drenabilidade de pavimentos asfálticos em Barra do Garças, Mato Grosso, Brasil

No que se refere às condições de segurança dos pavimentos, a drenabilidade merece atenção pois expressa a facilidade ou a dificuldade da ocorrência do fenômeno de hidroplanagem. Na presente pesquisa buscou-se estudar a drenabilidade de pavimentos urbanos avaliando a capacidade drenante de uma superfície pavimentada com concreto betuminoso usinado a quente (CBUQ) e outra em tratamento superficial duplo com capa selante (TSD), com um drenômetro construído seguindo as orientações de Lima e Dalla Riva (2014). Com os dados de vazão média para cada estação avaliados juntamente com os dados do ensaio de mancha de areia obtidos por Domingues (2018), foi possível obter uma equação que relaciona os resultados de drenabilidade com a textura do pavimento. Ao correlacionar essa equação ajustada, com os intervalos definidos por Pasquet (1968 apud CUBAR; DALLA ROZA, 2015), a Rua Coronel Elias Galvão recapeada com CBUQ, apresentou uma textura superficial média, indicada para vias com velocidade no intervalo de 80 a 120 km/h e o revestimento com TSD da Rua Presidente Kennedy foi classificado como muito grosseiro ou muito aberto, indicado para casos especiais que consistem em áreas com alto risco de hidroplanagem. Apesar de não apresentarem valores de drenabilidade (macrotextura) ideais segundo o Departamento Nacional de Infraestrutura de Transportes (DNIT), as condições das pistas avaliadas não oferecem risco à segurança do usuário, uma vez que são destinadas ao tráfego urbano.

Assessment of the Potential for Salt Damage to Asphalt Surfacings when Chloride-Treated Unpaved Roads Are Upgraded to a Sealed Standard

Experience gained during research into chemical dust control/fines preservation has indicated that the reduced maintenance on, and reduced gravel loss from, treated roads justifies the use of these chemical treatments as a cost-effective road maintenance and management strategy. Treatments also serve as a means of preserving layer thickness and integrity in stage construction if upgrading the road to a paved standard is planned. However, the potential for damage to primed bases and bituminous surfacings placed on chloride-treated layers as a result of salt crystallization underneath the surface during hot, dry conditions in arid and semi-arid climates has to be considered. A laboratory test method was therefore developed to gauge the potential for this type of damage. Calcium chloride, a commonly used dust palliative, was used in the experiment. The test, which simulated a worst-case scenario, followed by two field experiments that were evaluated for 36 months, indicated that salt damage to base materials, whether primed or unprimed, and to bituminous surface treatments or thin asphalt concrete layers is unlikely to occur on roads previously treated with calcium chloride. Care should be taken in the choice of surfacing if the electrical conductivity of the top 25 mm of treated material on the road exceeds 0.15 S/m prior to priming the base and placing the surfacing. This limit can be relaxed if laboratory testing, as described in this paper, indicates that salt damage is unlikely.

Economics of upgrading gravel roads to Otta seal surface

ABSTRACTMaintenance of low volume roads especially gravel roads is costly, and millions of funding annually are spent for aggregate replacement alone. Otta seal, compared to other bituminous surface treatments (BSTs) for low volume roads that require high-quality materials and specialized expertise, can be constructed using cheaper local aggregates and accessible equipment. However, only three states have reported Otta seal constructions and performance in the US. In this study, an economic analysis was conducted to compare the cost of maintaining a gravel road to the cost of upgrading an existing gravel road to a double Otta seal surface. This analysis was conducted at three levels: deterministic life-cycle cost analysis (LCCA), a stochastic Monte Carlo simulation-based LCCA, and a traffic based economic analysis. A generic one-mile rural road in Midwest was considered as a case study location. Although, according to the analysis conducted in this paper, an upgrade to Otta seal investment might be justified by maintenance savings, resorting to only such justification cannot warrant investment in most cases. The upgrade from gravel road to Otta seal, or any other BSTs, might be justified in terms of enhancing safety for road users and also encouraging economic development beneficial to local areas.

Deterministic and stochastic life-cycle cost analysis for Otta seal surface treatment on low volume roads

The US has a considerable length of unpaved secondary roads experiencing relatively low daily traffic volume. To maintain such roads, the US county secondary road departments spend millions of funds annually for aggregate replacement alone. Meanwhile, Otta seal has been reported as a low-cost bituminous surface treatment (BST) and dust mitigation technique. In consideration of its limited use in the US, Otta seal could be compared with chip seal, which is a commonly used BST in the US, from an economic viability perspective. In this study, through using the Minnesota case, a life-cycle cost analysis was conducted at two levels: (I) deterministic life-cycle cost analysis and (II) stochastic life-cycle cost analysis. Based on the analysis results, it was concluded that the Otta seal could potentially be an economic viable BST, and public agencies could use it to reduce maintenance cost of low-volume roads, especially when gaining access to uniformly graded aggregate, which is commonly not feasible for chip seal.

Study of Mechanisms that Generate Traffic Noise in the Tire–Pavement Interface for Low-Volume Roads in Brazil

Traffic noise has a negative influence on society, and minimum acoustic comfort standards must be maintained for individuals to be able to perform their daily activities. When traffic speeds exceed 40 km/h, the predominant noise source is tire–pavement interaction. This study assessed noise generated in the tire–pavement interface at different traffic speeds (40, 60, and 80 km/h), for different types of asphalt coatings applied in low-volume roads in the state of Sergipe, Brazil. Coatings included conventional asphalt mix and polymer-modified hot-mix asphalt concrete, cold-mix asphalt, and double bituminous surface treatment. An increase in noise was directly proportional to increased traffic speed and also varied with changing parameters such as voids, surface texture, and roughness. Because of the upper microtexture, a double bituminous surface treatment can be used as a good solution for quiet pavements in low-volume roads.

Estudo dos mecanismos de geração de ruído de tráfego na interface pneu-pavimento

Traffic noise is a problem that affects the society. However, they have to establish the triggers values for mini-mum standards of acoustic comfort to the people. The major factor to generate traffic noise is the tire/pavement interaction for speeds higher than 40 km/h. This work presents some evaluations of noise on the tire/pavement interface for different traffic speeds (40, 60 and 80 km/h), for several types of asphalt wearing courses applied in the State of Sergipe-Brazil (conventional asphalt mix and polymer-modified hot mix asphalt, slurry seal and double bituminous surface treatment). It was observed that the noise growth is proportional to the speed increase. The noise also varies with changing parameters such as voids, surface texture and roughness. It was proposed a prediction model to quantify the noise at the tire/pavement interaction from the speed and surface characteristics of asphalt wearing courses. The designers have now additional tools to indicate alternative pavements to critical urban roads, contributing to increase the society acoustic com-fort, knowing as quit pavements.

Otta Seal Surfacing

Natural gravel materials have traditionally been used for upgrading roads from earth to gravel or for regraveling existing gravel roads. However, serious concerns have arisen regarding the continuous use of vast amounts of gravel—a nonrenewable, finite resource—which not only is being rapidly depleted in many countries but also is unsustainable in the medium to long term. This problem has prompted road engineers to consider the use of low-cost bituminous surface treatments on these gravel roads as an alternative to regravelling. One type of surfacing that can provide an economic and practical alternative to traditional surfacings, such as the chip seal, is the Otta seal. Unfortunately, lack of information regarding this relatively new type of bituminous surfacing has suppressed its more widespread use despite its excellent performance in a number of countries. In view of this problem, state-of-the-art information on the provision of the Otta seal surfacing as an economic and practical alternative to the more traditional bituminous surface treatments is presented. The origin, properties, and design and construction of the Otta seal are outlined, and its implementation impacts and the various factors that contribute to its sustainability are discussed. Brief information is presented on the global use of the Otta seal.

Use of Sweep Test for Emulsion and Hot Asphalt Chip Seals: Laboratory and Field Evaluation

Abstract Currently, the scope of the standard test method for sweep test of bituminous emulsion surface treatment samples (ASTM D7000) is limited to emulsion-based chip seals only. To this end, the objective of this study is to evaluate the sensitivity of the sweep test for both emulsions and hot asphalts, with respect to aggregate mineralogical types, aggregate precoating, aggregate moisture content, asphaltic materials type, and application rates of asphaltic materials. For the field evaluation, fifteen chip seal test sections were prepared with three asphaltic materials and five aggregates in a 9-acre parking lot. Two years after construction, each of the 15 sections were visually inspected for aggregate loss and bleeding. Each section was given a distress rating. The % aggregate loss from the sweep test was then compared with the field distress rating. Both laboratory and field tests indicate that overall, expanded shale lightweight aggregate is better than any crushed stone, whereas clay lightweight performed the worst among the six aggregates tested in this study. Precoated expanded shale lightweight aggregates performed better than uncoated shale lightweight aggregates, with respect to % aggregate loss. Between the two hot asphalts, PAC-15 performed better than AC20-5TR. In the case of hot asphalt, the % aggregate loss increases as moisture content increases in oven dry, air dry, and saturated surface dry aggregates. However, for emulsion, air dry aggregates performed the best. For both emulsion and hot asphalt, an increase in asphaltic materials application rate reduces the % aggregate loss significantly. Distress rankings in all 15 sections, except for one PAC-15 section, matched sweep test rankings. Overall, the results indicate that the sweep test using both emulsion and hot asphalt can be an effective tool for evaluation of performance of chip seals.

The Impact of Pavement Type and Roughness on Paint Marking Retroreflectivity

This article addresses the impact of asphalt type and roughness on paint pavement marking retroreflectivity. Marking retroreflectivity and pavement roughness data were collected on two-lane highways in North Carolina. A t test was used to analyze the data. It was found that the mean values of the retroreflectivity measurements for the plant mixed pavements are significantly higher than those for the bituminous surface treatment (BST; chip seal) pavements. The mean left-wheel international roughness index (IRI) values and right-wheel IRI values for plant mixed pavements are lower than for the BST pavement. The conclusion is that marking crews should consider applying higher-quality paint markings (thicker paint and more glass beads) on BST pavements to achieve the same service life as the markings on plant mixed pavements. This would provide drivers with a more consistent and uniform marking retroreflectivity and the agency or municipality with a more consistent marking schedule.

Development of Roughness Prediction Models for Low-Volume Road Networks in Northeast Brazil

Roughness evaluation is the most effective way to diagnose pavement condition for design and decision making. The index most commonly used worldwide to indirectly describe the surface condition of asphalt pavements is the international roughness index (IRI). However, few studies have tried to predict the pavement performance of low-volume roads (LVRs) on the basis of the IRI, especially for LVRs in tropical regions. In an attempt to remedy that lack of knowledge, this paper presents IRI-based prediction models developed for asphalt pavement LVR networks in northeast Brazil. The following independent variables were considered to affect the IRI: Thornthwaite's aridity index, which describes local climate; the modified structural number, representing pavement bearing capacity; and the cumulative number of equivalent single-axle loads, representing the traffic applied to the pavements. A multiple regression analysis was carried out, and the results showed that the IRI increases exponentially over time. The analysis of the model parameters confirmed their significance, and the R-square values were 0.87 and 0.94, respectively, for low-volume roads with hot asphalt mixes and bituminous surface treatments. The hot-mix asphalt model was compared with that of the Highway Development and Management Model and with other models developed in research also sponsored by the World Bank. Because of regional differences (especially climate and materials), the models proposed in this paper provide a better estimation of roughness progression in LVRs of the northeast of Brazil.

Direct Measurement of the Impact of Heavy Loads on Thin Membrane Pavements

This paper presents the results of a field study of the loads imposed by heavy oilfield cranes (with hydraulic suspensions and super single tires) on thin membrane asphalt pavements in Alberta, Canada. Three 150-m test road sections (thin asphalt wearing course, bituminous surface treatment, and granular surface) were built and instrumented for strain at the bottom of the asphalt layer, surface deflection, and subgrade pressures. Temperature and moisture profiles were also measured. Field testing involved controlled speed experiments of standard axle configurations and heavy-axle (12,000-kg) vehicles with and without hydraulic suspensions. Focusing on the hot-mix asphalt section, this paper presents a description of the test road design, instrumentation, and testing plan, followed by some results and findings from two seasons (spring and fall 2005) of testing. Vertical stress in the subgrade, longitudinal interfacial strain, and surface deflection are compared for three vehicle types used in the test. Results from tests show that subgrade stress and interfacial strain are very similar for the standard axle configuration during spring compared with those of the cranes without the dolly during the fall season. It could be argued that on the basis of the pavement response, the cranes could operate during the winter season without the dolly (and thereby increase road safety by removing a long combination vehicle from the traffic stream) without causing substantial long-term deterioration.

Sensitivity of ASTM D7000 Sweep Test to Emulsion Application Rate and Aggregate Gradation

Presented in this paper are the effects of emulsion application rate and aggregate gradation on the performance of chip seal samples prepared and tested according to the ASTM D7000 Standard Test Method for Sweep Test of Bituminous Emulsion Surface Treatment Samples (sweep test). Aggregate loss of the samples was used as a performance indicator for chip seals. Limestone and granite aggregates were tested, and each aggregate type was tested with two gradations. Tests were carried out with three emulsion types: CRS-2, HFRS-2L, and HFRS-2. Each emulsion was tested at three application rates. Samples were tested at two different curing times, 2 h and 6 h. Statistical analysis of the chip loss results revealed that the current sweep test was not sensitive to emulsion application rate in the range tested. Results showed that gradation was a statistically significant factor. Coarse-graded aggregates resulted in high aggregate loss compared with fine-graded aggregates. From the overall results of the study, it is concluded that the current sweep test protocol is not suitable for use as a chip seal design tool because of its insensitivity to emulsion application rate. The test, however, is very sensitive to the combination of emulsion type, aggregate mineralogy, and gradation. It is recommended that the procedure be changed to use aggregate gradations representative of field aggregate. It is also recommended that the sweep test, with minor modifications, be used for evaluating compatibility between emulsions and aggregates and for estimating curing times required.

Pavement Preservation Funding and Performance in Washington State

The Washington State Department of Transportation (WSDOT) maintains more than 18,000 lane miles of state highway pavement, consisting of three pavement surface types: hot-mix asphalt, bituminous surface treatment (or chip seal), and portland cement concrete pavement. WSDOT has by legislative direction in state law maintained a specific budget item within the agency's capital budget for pavement preservation. Although these funds have not kept pace with inflation and are subject to other transportation spending priorities, such as maintenance, traffic operations, safety, congestion relief, and environmental retrofit, the end result is encouraging. But challenges loom. That point is illustrated by examination of what funds were spent by biennium and pavement type. This is followed by an overview of the current condition and performance of the state-managed pavements and where there are growing needs. A combined view of expenditures and performance suggests that the WSDOT process works reasonably well.