Physical properties of multi-layer seal surfacing in Turkey

Hot Mix Asphalt mixtures are often used as the top layer of pavement structures to build roads worldwide. Hot Mix Asphalt (HMA) mixtures combine bitumen and aggregate to produce roads. This paper aims to determine the optimum bitumen content (OBC) and investigate combining glass fiber in HMA with replacing a partial glass fiber of fine aggregate by Marshall Stability. The Hot Mix Asphalt was produced by mixing aggregate with 4% to 6% bitumen to obtain OBC to use in Hot Mix Asphalt Modified with glass fiber. Meanwhile, HMA modification was produced by mixing aggregate and OBC bitumen with 1% to 6% replacement glass fiber as a partial fine aggregate to improve the properties of Hot Mix Asphalt (HMA). Marshall Stability test, Aggregate Impact Value (AIV), Aggregate Crushing Value (ACV), Penetration Point, and Softening Point test was conducted. The effects of glass fiber in terms of stability, flow, stiffness, void in the total mix and void-filled bitumen in Marshall stability are investigated and compared with the control sample. The Optimum Bitumen Content (OBC) using Marshall Stability was chosen at 4.7% as OBC due highest stability value and passed in requirement standard JKR 2008. After analysis, the stability obtained for HMA Modified showed that adding 1%, 2%, and 3% glass fibers contributed to the highest stability values and passed the standards of parameters required by JKR 2008. Therefore, this paper can be concluded that the presence of glass fibers can significantly improve the performance of Hot Mix Asphalt (HMA).

The performance of asphalt-treated mixtures used in low-volume roads was evaluated, and their environmental benefits were assessed. Laboratory tests, including permeability, modified Lottman, Hamburg-type loaded wheel tracking, flow number, semicircular bend, dissipated creep strain energy, and dynamic modulus tests, were performed to examine the physical and mechanical properties of the asphalt-treated mixtures. Mechanistic–Empirical Pavement Design Guide (MEPDG) software was used to compare the performance of low-volume pavement sections with asphalt-treated mixtures to that of a conventional hot-mix asphalt (HMA) mixture. Life-cycle assessment was also conducted to quantify the environmental impacts of using asphalt-treated mixtures in lieu of conventional HMA mixtures in the construction of low-volume roads. Test results demonstrated that asphalt-treated mixtures containing limestone and reclaimed asphalt pavement exhibited similar properties to those of well-performing conventional HMA mixtures. MEPDG analysis showed that pavement sections with asphalt-treated mixtures exhibited similar performance to those with conventional low-volume HMA mixtures. Life-cycle assessment indicated that using asphalt-treated mixtures in low-volume roads could result in reductions of up to 29% in carbon dioxide emissions, 29% in energy consumption, 39% in water consumption, and 42% in hazardous waste generation.

Premium connections are commonly employed in wells subjected to high temperature and high pressure (HTHP) conditions. The key parameter in evaluating the sealing capability of premium connections is the contact condition between the sealing surface. This paper presents a method based on phased array ultrasound testing (PAUT) technique to examine the metal-to-metal contact states of the seal surface in premium conditions, and presents experimental work on contact status of the seal surface in premium tubing connections using PAUT, testing impacts of torque, seal surface defects and thread compounds dosage. The experimental findings demonstrate an inverse relationship between the observed ultrasonic reflection amplitude and the applied torque on the premium. Additionally, there is a robust exponential correlation manifested between the ultrasonic reflection amplitude and the torque exerted on the premium. The ultrasonic reflection amplitude at the defect of the seal surface increases. Under equivalent make-up torque conditions, the ultrasonic reflection amplitude on the sealing surface of premium connections escalates as the dosage of thread compounds diminishes, and the importance of precise control of the amount of thread compound used was confirmed. These data demonstrate that PAUT provides a reliable detection technique for performance assessment on premium connections, both in quality control and field inspection.

Utility of polyparaphenylene terephtalamide fiber in hot mix asphalt as a fiber

The Minnesota Department of Transportation (Mn/DOT) built the Minnesota Road Research Project MnROAD between 1990-1993. The 2.5-mile low volume road and the 3.5-mile mainline consists of a 2-lane roadway that originally contained gravel, hot mix asphalt, and concrete test cells designed for both low volume roads and interstate traffic. The mainline interstate cells are trafficked by public interstate traffic and the low volume road has a Mn/DOT 5-axle tractor-semi-trailer to simulated conditions of rural roads in two load configurations, resulting in the same equivalent axle loads or ESALS. MnROAD is located in a wet freeze zone that has affected both its base and subgrade materials with seasonal frost movements. This movement has slowly deteriorated each test cells ride over time. MnROAD has monitored the frost movements using frost pins and has measured the ride (international ride index – IRI) using high-speed profilers over for the life of the project. This paper investigates the loss of ride from both environmental and traffic loadings and how they have combined to cause the deterioration of ride over the last 10 years at MnROAD. The findings suggest that our current process to develop a mechanistic empirical design is currently missing the fact that seasonal differental frost movements play an important role in pavement performance in northern climates and need to be taken into account.

The rapid development of heavy industry in Vietnam leads to the establishments of steel industry. Steel slag, a by-product of steelwork industry, under Vietnamese’s law, was considered as a deleterious solid waste which needed to be processed and landfilled. However, this has changed recently, and steel slag is now seen as a normal or non-deleterious solid waste, and has been studied for reuse in the construction industry. In this study, steel slag was used, as a replacement for mineral aggregate, in hot mix asphalt. Two hot mix asphalt mixtures with an equivalent nominal aggregate size of 12.5 (C12.5) and 19 mm (C19) were produced using steel slag. In addition, one conventional hot mix asphalt mixture of C19 was produced using mineral aggregate for comparison purpose. Investigation in laboratory condition and trial sections was carried out on Marshall tests, surface roughness, skid resistance, and modulus of the pavement before and after applying a new surface course of hot mix asphalt. The study showed that all steel slag asphalt mixtures passed the Marshall stability and flow test requirements. The skid resistance of steel slag hot mix asphalt mixtures for the surface course satisfied the Vietnamese specification for asphalt. Moreover, the pavement sections with the surface course of steel slag hot mix asphalt showed a considerable higher modulus than that of the conventional one. Only the roughness of the surface course paved with C19 did not pass the requirement of the specification.

The use of resources is increasing due to continuous increase in world population and rapid industrialization, while natural resources are being exhausted day by day. Usage of waste materials or by-products in highway construction has substantial environmental and economic benefits. In this study, the usage of cullet and waste glass bottle dust as mineral filler material in hot mix asphalt as an alternate to traditional crushed stone dust was investigated. Optimum bitumen content was determined by the Marshall mix design method by using six different bitumen contents (4.0%, 4.5%, 5.0%, 5.5%, 6.0%, and 6.5%). With the optimum bitumen content, three different mineral filler types (cullet, glass bottle waste, and stone dust) and six different filler ratios (4%, 5%, 6%, 7%, 8%, and 9%) were used to prepare asphalt mixture samples. Samples were performed using the Marshall stability test, and the results were compared. It is concluded that cullet and glass bottle waste can be used in asphalt mixtures as a mineral filler alternate to crushed stone dust if the economic and environmental factors favor it.

Mechanical characterization of asphalt tear-off roofing shingles in Hot Mix Asphalt

Obtaining adequate density is a major requirement in the construction of hot mix asphalt (HMA) pavements. Density is very much related to the air voids. As air voids increase, the density decreases. This study determined the maximum in-place air void for impermeable HMA pavements. A total of 497 core samples were obtained from 57 different ongoing HMA construction projects immediately after rolling. Nine different mix types utilised in this study were fine dense-graded 9.5 mm, 12.5 mm, 19.0 mm and 25.0 mm nominal maximum aggregate size (NMAS) mixes, coarse dense-graded 9.5 mm, 12.5 mm and 19.0 mm NMAS mixes, and Stone Matrix Asphalt (SMA) 9.5 mm and 25.0 mm NMAS mixes. Bulk specific gravity of each core sample was determined using both American Association of State Highways and Transportation Officials (AASHTO) T 166 and vacuum sealing methods, and permeability was determined using American Society for Testing and Materials (ASTM) PS129-01. This study found that in-place air void content was the most significant factor affecting permeability. The in-place air voids for dense-graded HMA pavements should not exceed 7%.

With the growing need for sustainable and long-lasting paving materials, researchers have turned to innovative additives to improve the performance of bitumen and asphalt mixtures. Conventional bitumen often fails under heavy traffic loads and harsh climatic conditions, necessitating modification. This study aimed to improve the performance of bitumen and hot mix asphalt (HMA) by co-modifying them with a 4% styrene-butadiene-styrene (SBS) polymer and varying ratios of novolac resin. The results offered that the optimum ratio was 2% Novolac with 4% SBS. The physical and mechanical properties were evaluated through penetration tests, softening point, penetration index, dynamic shear rheometer (DSR), Marshall Stability tests, indirect tensile strength (ITS), tensile strength ratio (TSR), and wheel tracking. The modified mixture offered an improvement in penetration index from -1.89 to +1.3, a 38.7% increase in stability, a 40.9% increase in indirect tensile strength (ITS), and a 66.2% increase in moisture resistance. In comparison, the depth of permanent deformation was reduced by 58%. These results indicate significant improvements in stability, moisture, and deformation resistance, making it a promising option for developing more efficient asphalt mixtures. It also aligns with sustainable construction goals by reducing the need for frequent maintenance and extending pavement life.

Many road networks are using hot mix asphalt (HMA) to construct pavement layers. The Marshall method is the common procedure used in the design of the HMA and used at the time of the construction of the roadway to quality control. The present work is using ceramic fiber as a reinforcement to improve the characteristics of the HMA. The Marshall properties are examined by several tests such as Marshall stability test, and the flow test. The group of samples was made by utilizing 0.50, 1.0, 1.5, and 2.0 percentages of ceramic fibers by the total weight of the mixture. The results of the experiment showed the maximum Marshall stability occurred at a value of 1% ceramic fiber; the flow value decreased with increasing of fiber content, and the maximum Marshall quotient occurred at a value of 1% ceramic fiber. Also, the air voids, void filled with asphalt, and the void in mineral aggregate increased with increasing ceramic fiber content.

Stakeholders in the construction industry have lately enacted various initiatives to render it more sustainable. In the case of roadway construction, in particular, tremendous efforts are being placed at various levels to achieve 'green roadways' and 'green asphalt pavements'. Along these lines, this paper discusses the benefits of incorporating recycled concrete aggregates (RCA) from construction demolition waste (CDW) in asphalt mixtures. As such, use of CDW cuts down on the consumption of natural aggregates, a valuable and scarce natural resource in the context of Lebanon - the scope of this study. The study specifically evaluates the feasibility of replacing various percentages of the fine aggregates in hot mix asphalt (HMA) with fine RCA. Asphalt mix designs are developed and evaluated for various percentages of fine RCA, followed with mechanical performance tests. Analysis of testing results for Marshall stability and indirect tensile strength tests confirms the feasibility of replacing up to 30% by mass of fine aggregates in HMA with fine RCA.

This paper evaluates the replacement of natural aggregate coarse fraction for recycled concrete aggregate (RCA) in hot mix asphalt (HMA) concrete production, an area in which studies are recent and scarce. Crushed stone coarse aggregates (CSCA) were replaced by RCA with a 30 MPa compressive strength in the following percentages: 0, 25, 50, 75, and 100%, and mixed with asphalt cement (AC) 50-70. Volumetric and mechanical properties resulting from the Marshall mix design method, along with permanent deformation and durability by the moisture-induced damage test (Lottman), were analyzed. The results indicate that, although RCA shows higher absorption, higher Los Angeles abrasion, and lower density than the crushed stone aggregates, the mixtures showed satisfactory results for use as an asphalt concrete surface layer on low-volume roads. Wheel tracking tests presented permanent deformations ranging between 4.4 and 9.3%. It was also perceived as an adhesiveness improvement in the RCA mixture. The resul...

On low-volume roads, where crash frequency is less than on high-volume roads, the role of procedures alternative to and complementing crash investigations becomes substantially more important; safety inspections as a proactive approach to road safety can be very effective for this class of roads. From the results of the European Union research report Identification of Hazard Location and Ranking of Measures to Improve Safety on Local Rural Roads, a safety risk index (SRI) was formulated as a measure of risk that uses the safety inspection as the primary source of information associated with design consistency assessment of the horizontal alignment. Moreover, because of its quantitative evaluation, the SRI can be used to determine benefits and a cost–benefit ratio of different intervention strategies. Then, since there are often situations in which the available budget will not be enough to undertake all the measures in the road network, an SRI-based optimization algorithm was defined for selecting projects to be included in the budget.

Current and past investigations into road accidents have mainly focused on high-volume roads which have experienced a significant number of collisions. However, low-volume roads also record crash data which merit analysis to understand the causes of accidents and find potential countermeasures. This study focuses on unsignalized intersections linking major highways and minor stop-controlled local roads that operate with very low traffic volumes. In this scenario, an over-abundance of zero observations has to be accounted for. To address this issue, zero-inflated Poisson and negative binomial regression models have been calibrated and analyzed to find the geometric and operational factors which contribute most to the crash rate. Random effects have also been considered to account for unobserved heterogeneity inherent in the grouping of intersections within the database. The results indicate that the mixed-effect negative binomial model had the best prediction performance. Developing models for subgroups of crashes, for example, failure-to-yield and other types of crash, resulted in better prediction performance. The major road’s average annual daily traffic and the surface type (i.e., paved or unpaved) of minor road approaches had a significant effect on the frequency of all crash types. The type of intersection (three- or four-legs), the skew angle of intersection, deviation angle of near curves, and operating speed differences also had statistically significant effects on the frequency of crashes that do not include the failure-to-yield.