Analyzing the stripping potential of warm mix asphalt using imaging technique

In asphalt mixtures, stripping occurs when the bond between the asphalt and the aggregate is broken due to the intrusion of water within the asphalt aggregate interface. Warm mix asphalt (WMA) is a technology that allows significant reduction in mixing and compaction temperatures of conventional hot mix asphalt. However, WMA is susceptible to moisture damage due to its lower production temperature. This can cause adhesive failure, hence stripping of asphalt binder from the aggregates. In this study, direct tensile strength (DTS) and indirect tensile strength (ITS) tests were applied to fracture the mixture specimen. Imaging technique was applied on the fractured faces of asphalt mixture to quantify the adhesive failure susceptibility due to the destructive effects of moisture. The results showed that adhesive failure increased with the number of freeze and thaw cycles and mixtures prepared with PG-76 binder exhibited lower adhesive failure compared to PG-64 binder. From fractured ITS samples, most of broken aggregates were found located in the vicinity where the indirect tensile load was applied. On the other hand, high adhesive failure was obtained at the center portion where maximum tensile stresses were developed. The image analysis method employed in this work has proven to be very effective to analyze the deterioration of asphalt mixtures subjected to moisture conditioning

Effects of adhesion failure on moisture damage of warm mix asphalt containing cecabase additive

Campuran asfalt bersuhu sederhana (WMA) adalah teknologi yang membolehkan pengurangan ketara suhu pencampuran dan pemadatan campuran asfalt panas lazim.Teknologi ini boleh menjimatkan kos, meningkatkan kebolehkerjaan, mengurangkan kesan pengeluaran gas rumah hijau dan mesra alam. Walau bagaimanapun, WMA mudah terdedah kepada kerosakan lembapan sebagai akibat suhu pengeluaran yang lebih rendah. Hal yang demikian menyebabkan kegagalan rekatan, dan seterusnya pelucutan pengikat asfalt daripada agregat. Dalam kajian ini, bahan tambah campuran suam Cecabase digunakan untuk menurunkan suhu pengeluaran dan meningkatkan keboleh-rekatan asfalt dengan agregat. Pengikat jenis PG-64 dan PG-76 digunakan untuk menyediakan spesimen ujian. Bertindak sebagai surfaktan apabila dicampurkan dengan pengikat asfalt, Cecabase menggalakkan rekatan pada antara muka pengikat asfalt dan agregat. Keputusan ujian makmal secara keseluruhannya menunjukkan bahawa penambahan Cecabase tidak memberi kesan yang ketara ke atas reologi bahan pengikat dan kandungan pengikat optimum. Pendekatan baru melalui analisis imej digunakan untuk mengklasifikasikan kerentanan kegagalan rekatan dalam campuran asfalt sebagai akibat kerosakan lembapan. Hasil kajian menunjukkan kegagalan rekatan meningkat dengan bilangan kitaran beku dan cair dan campuran yang mengandungi pengikat PG-76 mempamerkan kegagalan rekatan yang lebih rendah berbanding pengikat PG-64. Ujian tegangan langsung substrat pengikat-agregat dan ujian tarik-keluar dijalankan untuk menilai kegagalan rekatan. Warm Mix Asphalt (WMA) is a technology that allows significant reduction in mixing and compaction temperatures of conventional hot mix asphalt. It is a cost effective technology that can improve mixture workability, reduces greenhouse gas emissions, and is environmental friendly. However, WMA is susceptible to moisture damage due to its lower production temperature. This can cause adhesion failure, hence stripping of asphalt binder from the aggregates. In this research, Cecabase warm mix additive was used to lower the production temperature and enhance the asphalt binder adhesion properties with aggregate. Two binders, PG-64 and PG-76, were used to prepare the test specimens. As a surfactant and when blended with asphalt binder, Cecabase promotes adhesion at the binder-aggregate interface. Therefore, the overall laboratory test results showed that addition of Cecabase had no significant effects on binder rheology and optimum binder content. A novel approach using image analysis was used to measure the asphalt mixture adhesion failure susceptibility due to moisture damage. The results showed that adhesion failure increased with the number of freeze and thaw cycles and mixtures prepared with PG-76 binder exhibited lower adhesion failure compared to PG-64 binder. To assess the adhesion failure, binder-aggregate substrate direct tensile and pull-off tension tests were carried out. An accelerated laboratory vacuum saturator (ALVS) moisture conditioning was fabricated to condition the binder-aggregate specimens

Effects Of Adhesion Failure On Moisture Damage Of Warm Mix Asphalt Containing Cecabase Additive

Warm Mix Asphalt (WMA) is a technology that allows significant reduction in mixing and compaction temperatures of conventional hot mix asphalt. It is a cost effective technology that can improve mixture workability, reduces greenhouse gas emissions, and is environmental friendly. However, WMA is susceptible to moisture damage due to its lower production temperature. This can cause adhesion failure, hence stripping of asphalt binder from the aggregates. In this research, Cecabase warm mix additive was used to lower the production temperature and enhance the asphalt binder adhesion properties with aggregate. Two binders, PG-64 and PG-76, were used to prepare the test specimens. As a surfactant and when blended with asphalt binder, Cecabase promotes adhesion at the binder-aggregate interface. Therefore, the overall laboratory test results showed that addition of Cecabase had no significant effects on binder rheology and optimum binder content. A novel approach using image analysis was used to measure the asphalt mixture adhesion failure susceptibility due to moisture damage. The results showed that adhesion failure increased with the number of freeze and thaw cycles and mixtures prepared with PG-76 binder exhibited lower adhesion failure compared to PG-64 binder. To assess the adhesion failure, binder-aggregate substrate direct tensile and pull-off tension tests were carried out. An accelerated laboratory vacuum saturator (ALVS) moisture conditioning was fabricated to condition the binder-aggregate specimens. The results indicated that short term and long term aged binders when subjected to ALVS, were susceptible to moisture damage. In order to gain fundamental insight, the Surface Free Energy (SFE) of Cecabase-modified binder was evaluated using contact angle Goniometer and dynamic Wilhelmy plate device. The analytical measurements based on SFE results showed that Cecabase improved the spreadibility of asphalt binder over the limestone aggregate particles. In addition, the work of adhesion improved with the addition of Cecabase. The compatibility ratio is an indicator of moisture susceptibility and indicated that the granite aggregates were less resistant to moisture damage compared to limestone aggregates

Evaluating the Surface Free Energy and Moisture Sensitivity of Warm Mix Asphalt Binders Using Dynamic Contact Angle

From the environmental conservation perspective, warm mix asphalt is more preferable compared to hot mix asphalt. This is because warm mix asphalt can be produced and paved in the temperature range 20–40°C lower than its equivalent hot mix asphalt. In terms of cost-effectiveness, warm mix asphalt can significantly improve the mixture workability at a lower temperature and thus reduce greenhouse gas emissions, to be environment friendly. However, the concern, which is challenging to warm mix asphalt, is its susceptibility to moisture damage due to its reduced production temperature. This may cause adhesive failure, which could eventually result in stripping of the asphalt binder from the aggregates. This research highlights the significance of Cecabase warm mix additive to lower the production temperature of warm mix asphalt and improvise the asphalt binder adhesion properties with aggregate. The binders used in the preparation of the test specimen were PG-64 and PG-76. The contact angle values were measured by using the dynamic Wilhelmy plate device. The surface free energy of Cecabase-modified binders was then computed by developing a dedicated algorithm using the C++ program. The analytical measurements such as the spreadability coefficient, work of adhesion, and compatibility ratio were used to analyze the results. The results inferred that the Cecabase improved the spreadability of the asphalt binder over limestone compared to the granite aggregate substrate. Nevertheless, the Cecabase-modified binders improved the work of adhesion. In terms of moisture sensitivity, it is also evident from the compatibility ratio indicator that, unlike granite aggregates, the limestone aggregates were less susceptible to moisture damage

Urban mining for asphalt pavements: A review

The increasing consumption of natural resources for road construction and generation of urban waste materials are two global ecological problems. Urban mining aims to convert waste materials into raw materials for industrial production, and as a result, address both problems simultaneously. This study explores the potential of urban mining for asphalt pavement surface courses. In the first part, as each country/region has its unique challenge with waste materials, a screening method taking the EU and Switzerland as case studies is employed to select waste materials that potentially qualify for asphalt surface courses. The second part presents a review of laboratory studies regarding the performance of asphalt mixtures with selected waste materials. Based on the industrial experience, the third part dis- cusses the technology, specifications and cost considerations of asphalt surface courses with waste materials. Furthermore, the technical maturities for using waste materials are estimated in terms of technology readiness level (TRL). Overall, the paper demonstrates that various categories of waste ma- terials can be potentially used in asphalt surface courses, revealing urban mining opportunities. The selected waste materials may improve the performance of asphalt mixtures with optimization of several factors, such as the fraction size and amounts of waste materials for addition or replacement. The TRL results showed that using crumb rubber (wet process) and steel slag are currently more mature than using other waste materials in asphalt surface course

Effect of waste PET and CR as sand replacement on the durability and acoustical properties of semi dense asphalt (SDA) mixtures

Construction materials research is consistently striving to improve sustainability, in the reduction of virgin materials by use of otherwise landfilled materials of the same purpose. Crumb rubber (CR) from end-of-life tires and polyethylene terephthalate (PET) from post-consumer liquid containers are two of the most commonly circulating forms of waste in the urban environment. This study investigated the replacement of semi-dense asphalt (SDA) sand by untreated mechanically shredded CR and PET, at 2.5 and 5.1% respectively by total mass of aggregates. The mixtures were evaluated by compactability, indirect tensile strength (ITS), fracture energy (FE), water sensitivity by ITS ratio (ITSR%), surface texture and acoustic absorption tests. After compaction, the CR and PET samples experienced an elastic rebound effect, which resulted in the air voids being higher than expected. Also, the PET samples required more compaction energy. The ITS, FE and ITSR% were significantly reduced with CR replacement, while the PET mixture performed similar to the control, especially in FE. The sound absorption was related more to the air voids than the material type, although the absorption coefficients of the SDA was not found to be significant. The CR reduced the texture level of the pavement significantly in comparison to the control, while texture level remained the same for the PET mixture, despite a difference in the porosity. Further studies were performed using a mixture replacing PET by aggregate volume at 5.1%, comparing it to the control SDA in terms of low temperature cracking and permanent deformation at 50 °C. While the compactability of the PET mixture was now similar to that of the control, the resistance to cracking and permanent deformation was lower. Although the PET mixture had some interesting ductility properties, the replacement of sand by CR and PET is not recommended, and the more common use as asphalt mixture modifiers with fairly low addition contents of around 1% is more sound

Modification of asphalt mixtures for cold regions using microencapsulated phase change materials

Phase change materials (PCMs) may be used to regulate the temperature of road surfaces to avoid low-temperature damages when asphalt materials become brittle and prone to cracking. With this in mind, different asphalt mixtures were modified with microencapsulated phase change materials (i.e. tetradecane) to assess their thermal benefits during the phase change process. Likewise, the effect on the mechanical performance of PCMs as a replacement of mineral filler was assessed. Special attention was paid to dry and wet modification processes for incorporating the PCMs into the mixtures. The results showed that PCM modifications are indeed able to slow down cooling and affect temperatures below zero. Approximately, a maximum of 2.5 °C offset was achieved under the tested cooling conditions compared to the unmodified reference specimens. Regarding the mechanical response at 0 °C and 10 °C, the results indicated that the PCM modification significantly reduces the stiffness of the material in comparison with the values obtained for the reference mixture

Effect of waste materials on acoustical properties of semi-dense asphalt mixtures

Among the urban societal burdens rolling noise generation from tire pavement interaction and urban waste stand apart. Many urban waste materials can be used in pavements with comparable mechanical performance. Noise-related pavement characteristics such as porosity, sound absorption and surface texture, were measured for semi-dense low noise pavement mixtures using urban waste materials namely: recycled concrete aggregates, crumb rubber, polyethylene terephthalate and polyethylene. The results show that the use of these materials is a viable sustainable option for low noise pavements, however that may affect the noise reduction properties. With values around 0.2 at 1000 Hz, the sound absorption of all the mixtures is relatively low and the use of mean profile depth (MPD) alone is not enough to characterize the noise reduction properties. Surface texture was altered in different degrees depending on the waste material used. The results presented can aid in policy pertaining to noise abatement and waste reduction

Implementation of Parallel K-Means Algorithm to Estimate Adhesion Failure in Warm Mix Asphalt

Warm Mix Asphalt (WMA) and Hot Mix Asphalt (HMA) are prepared at lower temperatures, making it more susceptible to moisture damage, which eventually leads to stripping due to the adhesion failure. Moreover, the assessment of the adhesion failure depends on the expertise of the investigator’s subjective visual assessment skills. Nowadays, image processing has gained popularity to address the inaccuracy of visual assessment. To attain high accuracy from image processing algorithms, the loss of pixels plays an essential role. In high-quality image samples, processing takes more execution time due to the greater resolution of the image. Therefore, the execution time of the image processing algorithm is also an essential aspect of quality. This manuscript proposes a parallel k means for image processing (PKIP) algorithm using multiprocessing and distributed computing to assess the adhesion failure in WMA and HMA samples subjected to three different moisture sensitivity tests (dry, one, and three freeze-thaw cycles) and fractured by indirect tensile test. For the proposed experiment, the number of clusters was chosen as ten (k = 10) based on k value and cost of k means function was computed to analyse the adhesion failure. The results showed that the PKIP algorithm decreases the execution time up to 30% to 46% if compared with the sequential k means algorithm when implemented using multiprocessing and distributed computing. In terms of results concerning adhesion failure, the WMA specimens subjected to a higher degree of moisture effect showed relatively lower adhesion failure compared to the Hot Mix Asphalt (HMA) samples when subjected to different levels of moisture sensitivity

Effects of adhesion failure on moisture damage of warm mix asphalt containing cecabase additive

Warm Mix Asphalt (WMA) is a technology that allows significant reduction in mixing and compaction temperatures of conventional hot mix asphalt. It is a cost effective technology that can improve mixture workability, reduces greenhouse gas emissions, and is environmental friendly. However, WMA is susceptible to moisture damage due to its lower production temperature. This can cause adhesion failure, hence stripping of asphalt binder from the aggregates. In this research, Cecabase warm mix additive was used to lower the production temperature and enhance the asphalt binder adhesion properties with aggregate. Two binders, PG-64 and PG-76, were used to prepare the test specimens. As a surfactant and when blended with asphalt binder, Cecabase promotes adhesion at the binder-aggregate interface. Therefore, the overall laboratory test results showed that addition of Cecabase had no significant effects on binder rheology and optimum binder content. A novel approach using image analysis was used to measure the asphalt mixture adhesion failure susceptibility due to moisture damage. The results showed that adhesion failure increased with the number of freeze and thaw cycles and mixtures prepared with PG-76 binder exhibited lower adhesion failure compared to PG-64 binder. To assess the adhesion failure, binder-aggregate substrate direct tensile and pull-off tension tests were carried out. An accelerated laboratory vacuum saturator (ALVS) moisture conditioning was fabricated to condition the binder-aggregate specimens. The results indicated that short term and long term aged binders when subjected to ALVS, were susceptible to moisture damage. In order to gain fundamental insight, the Surface Free Energy (SFE) of Cecabase-modified binder was evaluated using contact angle Goniometer and dynamic Wilhelmy plate device. The analytical measurements based on SFE results showed that Cecabase improved the spreadibility of asphalt binder over the limestone aggregate particles. In addition, the work of adhesion improved with the addition of Cecabase. The compatibility ratio is an indicator of moisture susceptibility and indicated that the granite aggregates were less resistant to moisture damage compared to limestone aggregates