Road Materials and New Innovations in Pavement Engineering

The void bulk modulus reduction of porous asphalt mixtures was evaluated using the Gassmann's equation to describe the relationship between the various bulk moduli and the percentage of air voids in porous asphalt mixtures along with the theory of linear elastic material with voids. A continuum interpretation of the porosity of the material was presented and used in the paper. The void bulk modulus was considered to represent the air voids reduction of the porous asphalt mixtures. The data showed a larger reduction in the void bulk modulus for the dry state when compared to the saturation state. The void bulk modulus under the dry state decreased by 8.4% with the 25% reduction in the initial air voids. However, the void bulk modulus decreased by 7.8% under the saturation state.

Digital image processing technique is used to quantify the impact of aggregate gradation and compaction method on air voids distribution and aggregate orientation and distribution. The air voids distribution was found to be sensitive to water permeability than traditional volume indexes. A more orizontal orientation was found for the aggregate particles compacted in the Superpave gyratory compactor. On the other hand, aggregate particles appear to have more of a random distribution in vibratory compactor samples. Aggregate distribution was found to be sensitive to the aggregate gradation and type of compaction. Base on digital image process technique, analyze the microstructure of hot mix asphalt, and present a series of microstructure parameters including the air voids distribution, aggregate distribution and major axis angle distribution. The result illustrate that the microstructure indexes can evaluate the internal structure difference of hot mix asphalt.

In this paper, two types of polymer modifiers and an asphalt binder were used to prepare compound modified asphalt binders sealant for bridge expansion joints. The fine aggregates of a single gradation along with three corresponding types of asphalt-aggregate ratios were selected to prepare compound modified asphalt mixtures for the surface asphalt layer of the bridge expansion joint. Similarly, the coarse aggregates of a single gradation along with another three types of asphalt-aggregate ratios were selected to prepare compound modified asphalt mixtures for the base asphalt layer of the bridge expansion joint. This study evaluated the water stability of the mixtures for un-aged, and short-term and long-term oven aged conditions using the immersion Marshall test and the Freeze-thaw Split test. Additionally, the adhesion between the aggregate and the compound modified asphalt was evaluated before and after oven-aging. The water stability of the six compound modified asphalt mixtures for road surface and substrate were compared. The test results indicate that, before and after aging, the best compound modified asphalt mixtures for surface and base asphalt layers exhibited an adhesion index of 5 and retained stability and freeze-thaw strength ratios (TSR) above 90%. Furthermore, TSR of the un-aged asphalt mixtures was the highest when compared to the TSR at the other aging conditions. After short-term aging, a decrease in TSR was generally observed, however a slight increase in TSR was observed after long-term aging.

It is well-known that bituminous materials age during exposure to sunlight, heat and oxygen. This ageing process causes both the properties of the bitumen and the behavior in a typical asphalt mixture to change. Depending on the level of ageing, the bitumen or asphalt may become unsuitable for its intended application. Various methods exist for the analysis and characterization of ageing of bitumens. In this paper a potential alternative method that has not received much attention yet as an ageing characterization method is discussed. The Atomic Force Microscope (AFM) is a device that is used on a daily basis by scientists working specifically in the nanotechnology field. The AFM allows various properties of a sample to be investigated, including the surface morphology. Researchers have investigated the AFM as a method for evaluating properties of bituminous binders. During previous work the author has evaluated the effect of artificial laboratory ageing on the surface morphology of a specific binder. In this paper the general ageing process is summarized and the AFM technique for characterizing the surface morphology of bitumen samples, both neat and treated with TiO₂, are discussed. Data from various laboratory aged and field aged samples are presented.

Asphalt pavement, which is relatively easy to burn in comparison to cement concrete pavement, is not often used in road tunnel. By adding flame retardant (FR) additives, asphalt pavement would be made less flammable. In this paper, the effect of three different combinations of flame retardant additives on an asphalt binder flaming was evaluated using the oxygen index test method. Additionally, the effects of additives on the asphalt binder were evaluated in terms of penetration, softening point and ductility. Recommendations for the type and contents of additives were provided based on, both, the test results and some economic considerations.

The rheological properties of bitumen are improved by addition of small quantities of polymers. A review of different polymers such as Styrene-Butadiene-Styrene (SBS) Styrene-Butadiene-Rubber (SBR), Ethylene Vinyl Acetate (EVA) and Poly Phosphoric Acid (PPA) with emphasis on SBS and its microstructure is presented in this paper. The polymers are divided into two groups: elastomers and plastomers. SBS, an elastomer, has shown greater potential compared to other modifiers when blended with bitumen and improves the mechanical properties and rheological behavior of conventional bitumen. SBS is made up of styrene and butadiene monomer units. It was found that maltene interacts preferentially with the polybutadiene unit of SBS, whereas asphaltene interacts predominantly with the polystyrene unit. SBR is another elastomer which also has polystyrene and polybutadiene units with a different structural make up. EVA is a plastomer which when blended with bitumen has improved the rheological properties and stability, provided the asphalt has asphaltene content below a critical level. PPA is a liquid mineral polymer. Addition of PPA to asphalt contributes to more interactions within the asphaltenes network, thus increasing the elastic behavior. A study was also conducted to determine the influence of asphaltenes and maltenes on the rheological properties of polymer modified binders.

Unlike the AASHTO 1993 pavement design guide, the new Mechanistic Empirical Pavement Design Guide (MEPDG) is heavily dependent on asphalt mixture variables such as air void content, percentage binder, binder performance Grade (PG) at level 3 analyses. Therefore, it is important that pavement designers and engineers have sufficient knowledge of how a particular input parameter affects the MEPDG output or pavement performance during the service life. In this study, a one-to-one sensitivity of pavement performances such as rutting, cracking and International Roughness Index (IRI) to three mix variables namely, air void, asphalt content and binder PG are studied. It is shown that PG grade affects asphalt concrete (AC) rutting significantly. Alligator cracking is sensitive to air voids and binder content. Longitudinal cracking and IRI is not sensitive to these three mix design variables.

Triaxial repeated load permanent deformation tests of two asphalt mixtures were conducted to investigate the flow characteristics of asphalt mixture under high temperature and heavy load. Then, a continuous function between permanent strains versus loading cycles was derived, and flow number was calculated by some algebraic manipulations of the second derivative of the proposed function. It is indicated that permanent strain increase with test temperature and stress, and permanent strain of mixture with larger maximum nominal aggregate size is smaller. The proposed function can well describe the whole three stages of permanent deformation for asphalt mixture. The calculated flow number is also different with mixture gradations and decreases with the stress and temperature. But the decrease range becomes smaller at higher stress levels and temperatures, especially at the extreme condition, and the difference among asphalt mixtures is inconspicuous. At this moment, permanent deformation resistance of different mixtures could not be distinguished by the flow number.

Natural rock asphalt is one of the locally produced modifiers currently used in some asphalt mixes in China. In this study, the laboratory performance of an asphalt mix that was modified with different dosages of Chinese rock asphalt was evaluated. Various laboratory tests including multiple creep test, freezing-thawing split test, split test at low temperature, and dynamic modulus were conducted to characterize the material properties of the modified rock-asphalt mix and are discussed in this paper. Overall, the results indicated substantial improvement in both the high temperature and moisture-resistance performance of the mix at the optimum dosage of the rock-asphalt.

Hansen solubility parameters of aged asphalts and rejuvenators were determined by dissolving method with twenty seven solvents, whose Hansen solubility parameters were known. The computation program was used to perform sphere simulation for the soluble points, in which the center was the Hansen solubility parameter of sample. About 80% of the simulation results were consistent with the experimental data. The Hansen solubility parameters differences between rejuvenator A₂ and three aged asphalts were small, which indicated compatibilities of them were good. The compatibilities between rejuvenator D and three aged asphalts were bad.

The expansion of the swelling clays when subjected to moisture increase can be simulated to a hidden cancer. Growth of tiny molecules composed of silica tetrahedral and alumina octahedral can reach a stage that causes harm to light structures. The cost of annual maintenance is estimated into billions of dollars worldwide. Extensive research was conducted to stabilize this problematic soil using chemical methods. Stabilization of swelling clays using lime or cement is a well known efficient chemical approach. Research works on optimum lime or cement content is established for many types of clay. The use of lime is more popular than cement due to its lower cost. However, the cement is found to be better in reducing the expansion and improving the soil strength. In order to optimize the improvement with a yet tolerable cost it is intended to investigate treating the clay using a combination of cement and lime. The previous research works carried out by other researchers indicated that the optimum stabilization lime content is expected between 3.5 to 5% of the dry weight of the soil. A research study conducted on Al-Gatt clay shale focused on comparing the effect of adding a 4% lime content (The optimum content for lime only) with a lesser amount (2% by weight) consisting of cement and lime additives (1% lime and 1% cement). Stabilization of Al-Ghatt clay shale by using 4% lime reduced the swell percent by 3.3% in average. The use of 2% additive of cement and lime reduced the swell percent by 4.7% in average. The strength properties and bearing values were compared for the case of lime only and lime-cement additive. X-Ray Diffraction (XRD) tests were carried out for pure clay shale, clay shale with 4% lime additive and clay shale with 2% cement-lime additive. The effect on mineralogy is observed through the position and intensity of the peaks of common clay minerals. It is concluded that cement can be introduced with lime to achieve a better improvement with a reduced cost.

A large laboratory research project founded, by the European Community and involving Academies and Industry has been carried out to fill the gap between the empirical design rules of soil treatment by lime and the mechanistic design approach used for transportation infrastructures. This required a multidisciplinary approach both at macro/micro-scales, using common geomechanical test methods, microscope observations and micro scale tests. These tests were performed on samples of a silty soil that had been treated with respectively 1.5, 3 and 4.5 % calcic quicklime. The curing conditions were chosen as main parameters for the testing program, viz. time (up to 730 days) and temperature (20, 36 and 50 °C). Due to a lack of space, only results with samples cured at 20°C are presented in this paper. All evolutions of the mechanical parameters were coupled to the micro-scale test results. The aim of this analysis was to gain a better insight in the relation between strength macro-scale parameters and micro-scale reactions such as the development of CSH and CAH during pozzolanic reactions.

Data Mining (DM) techniques is a useful tool to explore complex relations between data with implicit information. It is than a potential tool to apply when a huge data is available and also to discover knowledgement. In this case DM techniques were applied to predict geomechanical properties of laboratory formulations of soil-cement mixtures used in Jet Grouting (JG) geotechnical works for the improvement of ground, mainly soft soils. These properties (uniaxial compressive strength (q_u) and Elastic Young Modulus (E₀)) are essential to design geotechnical structures against ultimate limit state (ULS) and the serviceability limit state (SLS). In this paper, three DM models, i.e. Artificial Neural Networks (ANN), Support Vector Machines (SVM) and Functional Networks (FN), are applied for q_u and E₀ predictions and the results compared with Eurocode 2 predictive formula. In order to understand how DM models work, a sensitive analysis procedure was applied to quantify the effect of the key parameters. Furthermore, several experiments were held, by applying of DM techniques in order to estimate E₀ normalized by q_u over time. The obtained results give a new contribution to understand the behavior of JG material that improves the construction control process of JG columns and reduces the costs of laboratory formulations.

An important priority for the Sarawak State of Malaysia is of providing road networks to enhance connectivity and economic development throughout the State. However, the more populated coastal areas along the South China Sea are covered by peat and other soft soil deposits. Construction of roads in such areas requires extensive ground improvement by preloading that is time consuming and at times also expensive. Electro-osmotic consolidation is a well known ground improvement technique for improvement of fine grained soft soils where a direct current introduced into the soil induces electro-osmotic flow of water from the anode to the cathode. Experiments were carried out in the laboratory to study the feasibility of electro-osmotic consolidation of an organic soil sample from North Sarawak. Commercially available prefabricated electric vertical drains were used as electrodes. This paper presents the experimental set-up, geotechnical characterization of the soil sample and the results of the tests conducted with incremental voltage gradient. Voltage and current were measured to assess the power consumption. The water content decreased and the shear strength increased significantly after 8 days of electrokinetic treatment. The results indicated a good potential for the application of electro-osmotic consolidation in organic soils.

Rigid pile composite foundation is often used as an effective ground treatment method in the construction of highways. The PCC (cast-in-place thin-wall concrete piles) composite foundation is more and more frequently used in highway ground treatment. The research conducted on this type of foundation is very little. This paper highlights the use of PCC in Yan-Tong highway. The design, construction and quality test of this method are introduced. Test results show that the pile quality is good and its bearing capacity is relatively high.

Because of the complexity of pile-soil interaction under the effect of horizontal load, the calculation theory and method for horizontal bearing pile are not perfect, so further study shall be conducted. Based on the basic field test of long elastic pile in a port project, the construction effect of cement injection pile has been evaluated according to the testing results in this paper. ABAQUS has been used for three-dimensional simulation calculation of the single pile in the testing area; smeared cracking model has been used for simulating the endurance of concrete; embedded element has been used to simulate the reinforcement bar in concrete. The inner force distribution in every elevation of pile has been calculated, and then compared with testing value and the results suggest that the precision of numerical calculation can meet the engineering requirements.

Bridge-bump often occurred at transitional section between bridge and subgrade in the highway. In this paper, the gravity abutment was treated with Wedged-shaped Flexible Geocell Slab [WFGS] .The treatment effects of WFGS were analyzed by MSC-MARC, which was one of general nonlinear finite element analysis software. The vertical displacement [VD] changes of the top subgrade and Geocell layers, which had uneven foundation subsidence [FS], were simulated using finite element analysis [FEA]. Thus, the layout positions of test equipment were obtained. Then, large scale model experiment and simulated settling curves of post-construction were carried out to study the adaptability of WFGS. By observing deformations of embankment top and measuring vertical displacements of Geocell layer, especially differential settlement between embank and abutment, WFGS was shown effectively for bridge-bump treatment. With WFGS, the differential settlement was less than 1.5cm when the FS was less than 12cm. However, effects of Geocell were not good enough when FS was more than 15cm, the rigid approach slab should be used together in this situation.

In order to locate damages in structures, Damage Location Vector method is introduced. This method treats structures as linear in the pre and post damage states by calculating a set of vectors. These vectors, designated as Damage Locating Vectors (DLVs), have the property of inducing stress fields whose magnitude is zero in the damaged elements (small in the presence of truncations and approximations). The DLVs are associated with sensor coordinates and are computed as the null space of the change in flexibility from the undamaged to the damaged state. In order to verify the effectiveness of the method, an experiment is carried out for single or multiple element damage scenarios. It is demonstrated that the method is effective when the damage extent reaches a certain level.

According to the oversize patching area on broke slab corners, a reasonable upper limit value was proposed through statistic analysis and equivalent annual cost (EAC) analysis on the data in pavement maintenance management system of Xiangtan-Leiyang Expressway. This upper limit value can be used as determination criteria between patching with asphalt concrete and full slab full depth replacement. It can play a vital role in restricting the appearance of oversize patching areas, and thus decrease the waste of maintenance funds.

Most construction projects involve earth removal operations. Careful management of truck fleets to perform these operations is considered crucial by earthwork contractors in Taiwan. This paper presents a hybrid mechanism to optimize the management of the truck fleets of earthwork contractors. We use discrete event simulation models to represent earthmoving operations, and these models are used to simulate schedules for dispatching truck fleets. We then apply genetic algorithms to select the optimal schedules with the least amount of operational time. A theoretical example proves that the proposed mechanism can determine near-optimal solutions efficiently. Finally, we develop a user-friendly interface so that earthwork transportation companies can use the proposed mechanism easily and effectively.

This study uses a value engineering analysis of second round collector road construction in Taipei harbor as means of investigating the feasibility of conducting value engineering (VE). A total of 24 factors, cited in related literature, were considered and the Fuzzy Delphi Method (FDM) was used to choose 10 evaluation factors. The Fuzzy Analytic Hierarchy Process (FAHP) was then adopted to analyze the overall assessment structure. The analytical methodology used in this research has potential use for public authority. In another words, the combination of FDM and FAHP is effective in showing value engineering assessment.

In order to solve the traffic congestion problems around Nantou area, the roadway network should be completely reviewed, especially for the National Highway 3's interchange system. The key assess is the Zucih bridge located at the edge of the Nantou city with the station 228K+500 on the National Freeway 3. Well constructed interchange system will definitely improve the traffic congestion problem in Nantou City. After that the Nantou County will possess the advantages for developing the industrious field. The purpose of this study is to conduct a quantifiable and non-quantifiable benefit-cost analysis of the construction project in order to evaluate the economic benefits of the location and route of the Nantou interchange. To do this, benefit-cost ratio(B/C) and net present value(NPV) will be used as quantifiable indicators, while for non-quantifiable indicators (such as land value, property value, and commerce benefits) more concrete figures will be used when possible in order to fully understand the economic benefits of this project. Further steps were taken to analyze the feasibility of the proposed construction. The findings of our research are to be used to contribute to the project's construction team.

The implementation of landslide probability analysis was undertaken in order to evaluate the impact of landsliding on closures of major mountain road networks in Guoshin Township in central Taiwan. To achieve this objective, an event-based landslide probability analysis method was adopted to establish a landslide prediction model using a set of training data from the landslides triggered by Typhoon Mindulle in July 2004. Landslide causative factors and triggering factors were selected in a logistic regression scheme so that the criteria for successfully distinguishing landslides from non-landslides were established. Landslide occurrence probability was mapped in the whole study area as well as along the road route. Locations of high potential for landslide occurrence were thus highlighted along the road route and were proposed for road closure during typhoon events. At last, the proposed locations for road closure were validated by historical road closures caused by subsequent typhoons after Typhoon Mindulle. Validation results show that the proposed model could be used in predicting road closures due to storm-induced landslides.

In this paper, various bidding methods including Open, Invitational, and Negotiated bidding were comparatively evaluated based on the associated construction costs, transaction costs, bid price, and service quality. Although open bidding was found to be beneficial in terms of reducing construction costs, it is associated with high transaction costs that can be minimized through internet usage Invitational bidding should be based on a pre-qualification criterion while negotiated bidding should be applied where market conditions are assumed to be competitively perfect. The results also indicated that the bid appraising method based on the lowest evaluated bid price and high quality service must be used in construction and technical projects, respectively. In general, the study results showed that the current Chinese bidding laws and regulations for construction projects need to be improved.

Consider that floating cars and fixed coil detectors have complementary advantages and the merit of Support Vector Machines technology, this paper uses Support Vector Machines technology at first to fuse two kinds of data, and make freeway incidents detecting. Secondly, combining with the characteristics of support vector, the freeway incident detection algorithm based on reduced training set and support vector machines is designed to use fuzzy cut set theory. The method reduces not only training samples but also training time and improves the practical application ability of incident detection algorithm based on maintaining the detection rate and false alarming rate.

Quality, cost, and accessibility of public transportation is a problematic issue in many developing countries. This paper summarizes the main aspects associated with implementation of the Bus Rapid Transit (BRT) systems in Colombia as a means of efficient public transportation in several cities of the country, including three (Bogotá D.C., Cali, and Barranquilla) of the four most populated cities (with population of over 1 million people). Implementation of the BRT systems benefited the cities in terms of: (i) improved operational conditions and administrative organization of the public transportation system, (ii) reduction in environmental pollution, (iii) enhancements in quality of life, and support of economical development, and (iv) improvement in safety. Despite these positive results, additional aspects identified in this paper to improve the Colombian BRT systems include: (i) further integration of the different transportation systems, (ii) implementation of advanced technologies for monitoring, assessing, and continuously adjusting the system, and (iii) modified relationship between land use and the transportation system.

This paper proposes a new kind of traffic noise analysis method based on the extensive traffic noise data obtained from Huidong county, Guangdong province of China. Plane traffic noise maps are made by a traditional method and compared with the real noise distribution. The results indicate that they do not match in the old city zone. In addition; integrated with factors such as acoustic characteristics, streets' shape, and building heights; CadnaA software was employed to determine the plane traffic noise distribution. Field investigations revealed the reasons why some zones in the city were not usual. Finally, conclusions and suggestions were made to reduce the deflections of noise distribution to make proper linear relationship between simulated noise data and in-situ noise data in the old city zone.

Nanomaterials have been generally applied in all fields all over the world, because of their distinctive physical and chemical characteristics. In order to improve the properties of asphalt and asphalt mixtures, the selection of nanometer materials for modifying the base asphalt was processed. Furthermore, a series of asphalt experiments were performed to analyze the basic performance of these asphalt with varying nanometer material contents. The tests included penetration, ductility, softening point, viscosity and atomic force microscope (AFM). Property comparison between modified asphalt and base asphalt was undertaken. Additionally, AFM images of modified asphalt at the optimum nanomaterials content were presented, which indicated that 2% carbon nano powders modified asphalt has an excellent uniformity structure in the base asphalt compared with microstructures of the other nanomaterials modified asphalt. Besides, mechanical performance tests of asphalt mixtures were carried out, and showed that the properties of nanomaterial modified asphalt were superior to those of the base asphalt.

Based on numerous research studies, superior properties such as stability, bonding, resistance, durability, etc have been observed with substances whose sizes are measured in nano-scale due to their high specific surface area; which maximizes active interaction between the nanoparticles and their environment. In this study, the high temperature rheological properties of a nanocomposite modified PG58 asphalt were evaluated in the laboratory. Compared to a conditioned base asphalt-binder, there was significant improvement in both the high temperature properties and the performance grade of the nanocomposite modified asphalt. These changes in the high temperature properties were primarily associated with the changes in the asphalt-binder morphology due to the presence of the nanocomposite and depended directly on the quality of the nanocomposite, concentration of the nanotubes, and its distribution in the asphalt-binder.