Recent Developments in Evaluation of Pavements and Paving Materials

Recent studies have shown that the sessile drop approach is a reliable method to measure contact angles on asphalt pavement materials. The measured contact angles, in turn, are utilized for computing the surface energy properties of asphalt binders and aggregates. Based on the surface energy and bonding strength characteristics of the materials, appropriate aggregates can be selected to construct pavements that are resistant to moisture damage. In this approach, surface roughness could be an important factor that could affect the contact angle measurements on aggregates. The main objective of the present study is to determine the differences in contact angle measurements on a limestone aggregate at different levels of surface roughness. Initially, contact angle measurements were conducted on selected points on the unpolished surface of the limestone specimen. Later, the same specimen was subjected to different stages of polishing using silicon carbide grits. At each stage, the contact angle measurements were repeated, as well as surface roughness was measured using a 2D profilometer. It was observed that there was a change in the contact angle measurements as the roughness of the surface decreased with polishing.

The quantification of discrete aggregate particle characteristics should allow for an increased understanding of how these influence the performance of pavement materials in general. Two advanced techniques, the three dimensional (3-D) laser scanning and scanning electron microscopy (SEM) are considered for the characterization of discrete particles of aggregates and sands respectively. This paper highlights examples of the use of both 3-D laser scanning and SEM techniques with the main objective of illustrating the application in the characterization of unbound materials. The results of image analysis from SEM and 3-D laser scanning device provided information in quantifying and identifying the differences between aggregate particles which may influence the overall performance of unbound pavement materials.

The newly developed skid resistance measurement system, ViaFriction, was employed to measure the skid resistance under different slip conditions such as the anti-lock braking system (ABS). The ViaFriction test system is equipped with four temperature sensors, which can acquire the temperature of the water, atmosphere, road surface, andtire. In this paper, tests at a driving speed of 60 km/h and 20% slip rate are performed under various temperature conditions. Through correlation and regression analyses, the influences of different temperatures on the skid resistance are studied. The influences from the air temperature and water temperature on the skid resistance measurement of road surfaces are decisive.

Polymers are currently added to asphalt to increase characteristics that essentially improve the life of the asphalt. One polymer commonly added to asphalt is Styrene-butadiene-styrene (SBS). This polymer is common due to its elastic properties that increase viscosity, elastic response, and complex modulus. Although this is known, the current PG grading system may not adequately show the attributes of polymer modified asphalt. Historically, additional tests, known as PG Plus tests, have been performed on polymer modified asphalt (PMB) to ensure the asphalt has been modified to the end user specification. The new multiple stress creep and recovery (MSCR) test has been proposed to eliminate the proliferation of plus specifications throughout the states. The current performance grading specification, AASHTO M320, and the elastic recovery test were compared to the new MSCR grading specification, AASHTO MP-19, to ascertain a more appropriate grading system. This will be studied by taking in-house polymer modified binders that were developed and verified to have achieved full interlocking by use of fluorescence microscopy and measuring the mechanical properties of the in-house polymer modified binders to obtain the continuous grade of the binders. The addition of polymers increased the rheological properties and high grades of the base binder, as well as increasing the traffic grades of the proposed MP 19 specification. Although, the low PG grade was not changed, the continuous grading system showed that addition of polymer did, in fact, change the low-temperature properties of the binder.

In Korea 97.6% of a total length in national highway system is paved. Particularly, most of national highway has been paved as asphalt pavement. Surface treatments are recommended to use in distressed asphalt pavements in national highway due to cost-effective, extension of pavement life, and improvement of surface performance such as friction and noise. By applying a cost-effective surface treatment at the right time, the pavement is restored almost to its original condition. Most of government agencies state that surface treatments are the most effective use of limited budgetary dollars to maintain roadway serviceability. Recently, polymer-modified emulsion is being used to improve the stability of surface treatment mixes. However, it is sensitive to curing time and content. In this study, influences of curing time and content on two types of polymer-modified emulsion used for microsurfacing and slurry seal mixes are evaluated using a load wheel tester (LWT) that is a traffic simulating device. It exhibits the approximate compacting effort of 1 million vehicle passes in less than 25 minutes when loaded with 125 lb (56.7kg) of lead shot weight in the laboratory. Based on the LWT test results, the compactability and stability of microsurfacing and slurry seal mixes using polymer-modified emulsions significantly increase as curing time increases. Two polymer-modified emulsions used in microsurfacing and slurry seal mixes show superior performance compared to a conventional emulsion. It can be postulated that polymer-modified emulsions would be more flexible with less bleeding.

It is an important topic on how to effectively manage highway maintenance with limited resources. It becomes even more critical when the demands for highway transportation increase significantly. Traffic channelization design as a technical method to divide traffic flow is a traffic organizing method. It can achieve good results in a very short period with minimum budget, but it may result in wheel path concentrated in the transverse profile of a pavement. To preserve pavement resources, this paper presents the expressway roadway translation method, which is based on asphalt pavement rutting model. It composes three basic design steps: (1) constructing rutting model, (2) designing translation plan, and (3) implementing the translation plan. A case study for Qingyin expressway is presented. The condition survey results indicated that there is good safety and it delays maintenance by 1.5 years. The expressway roadway translation method is sound in theory, clear in design procedure, and simple in operation. It has important theoretical and practical value by offering a completely new way of expressway maintenance management.

In this paper, a procedure for estimation of effective modulus of a multilayered hot-mix asphalt (HMA) pavement using intelligent compaction (IC) is investigated. A complete coverage of the level of compaction of each of the asphalt pavement layers was recorded using the intelligent asphalt compaction inalyzer (IACA) atInterstate highway I-35 in Norman, Oklahoma, USA. The collected IACA data allow determination of the level of compaction (density) at any selected location, for each layer. Considering the IACA estimated density, dynamic modulus of each of the selected locations for an individual pavement layer was measured from laboratory developed master curves. Thereafter, effective modulus of the three-layer pavement system was calculated for all of the selected locations using Odemark's method. The proposed technique was verified by conducting FWD tests at these selected locations. Analyses of the results show that the proposed intelligent compaction technique may be promising in estimating the effective modulus of the pavement layers in a nondestructive manner.

Adopting six sigma theories as the theoretical basis, this paper starts with the improvement of the quality inspection standards and then puts forward the six sigma standard of asphalt pavement construction quality inspection based on the surface segregation and the evaluation methods and steps of six sigma standards of the depth of the surface structure based on normal distribution. Finally, the evaluation index and method of asphalt pavement surface segregation based on six sigma are established.

The underground pipeline excavation in Taiwan has caused significant challenges for road authorities, even resulting in loss of lives and public property. This study reviewed the policies of public utility databases and common duct systems implemented in Taiwan. The questionnaires were designed based on the concept of building information modeling (BIM) and used to interview executives from road authorities, pipeline agencies, and engineering consultants companies to understand the current underground pipeline management in detail. According to the findings, respondents generally agreed that the concept of BIM is beneficial to underground pipeline management. This study provides a basis for improvements in road maintenance and management.

The National Highway pavement management system (PMS) in Korea is currently operated by the Ministry of Land, Infrastructure, and Transport Affairs (MOLIT) for efficient use of the budget through proper pavement maintenance. The PMS database system was developed in Excel spreadsheet for each road's history such as pavement material, maintenance method, and pavement conditions. In this study, we design a new PMS database system using GIS technology for national highways to overcome the restrictions of the existing PMS. The new designed PMS database system can provide pavement-related information more effectively than the previous PMS system. Also, it can secure the reliability of the pavement material for performing research and evaluating the exact pavement conditions.

This study performed crash accident analysis both before and after diamond grinding (DG) on a recent project section. After the completion of DG, the average crash occurrence was reduced by 15%, and there was an average international roughness index (IRI) reduction of approximately 40% immediately after treatment. Eleven projects were evaluated to derive a statewide trend on various surface characteristics of pavements due to DG, with the oldest section studied approximately 8 years after treatment. Immediately after DG, the average skid number increased by about 30%. Similarly, there was an average IRI reduction of approximately 40% immediately after the DG. Depending on the existing pavement conditions, the range of IRI reduction varies from 17 to 57%.

The mix proportion and mechanical property of polyethylene terephthalate (PET) concrete was studied by orthogonal test and mix proportion design. Different limestone, basalt aggregate and mineral was used to mix with melted PET to produce PET concrete. The effect of mineral materials, PET, and mineral/aggregate ratio (PETWA/AG), sand ratio, PET/mineral ratio (PET/MA), and materials of coarse aggregate on PET concrete mechanical property were analyzed. The results showed that the most important factor was PETWA/AG and then sand ratio and PET/MA. Basalt was better than limestone as coarse aggregate in PET concrete. From high to low compression strength sequence of PET concrete mixed with different mineral was fly ash with 5% talc, only mixed fly ash or Portland cement (PC), mixed fly ash with 5% asphalt, without any mineral. The best mix proportion of PET concrete was PETWA/AG=1/3, sand ratio=35%, and PET/fly ash=2~1.

Wedge splitting test is employed to study the effects of different specimen sizes and different crack depth ratios of roller compacted concrete on double-K fracture model parameters. Results show that with an increase in initial crack depth ratio α, the unstable fracture toughness K^un_IC increases while the initial fracture toughness Kⁱⁿⁱ_IC decreases. In the range of 0.4~0.6, α has a continuous effect on Kⁱⁿⁱ_IC. However, the effect on K^un_IC reduces with the increase of α value. For specimen size, when the height of the specimen, h, is smaller than 300 mm, the effect of specimen size on K^un_IC is significant, but it decreases when h is larger than 300 mm and smaller than 500 mm.