Pavement Performance Monitoring, Modeling, and Management

Because highways are the most common and the most advanced means of transport compared to other transportation systems in Turkey, alternative techniques and materials are constantly being investigated to develop innovative solutions for the construction of highway embankments and other types of earth structures. It is obvious that in highway projects, excavation, loading, and transportation costs of the material are the most important factors for the total cost, and improvement in subgrade soils would have significant economical side effects. In this research, extensive laboratory experiments have been performed to investigate the use of polypropylene fibers with the scope of two different low plasticity clay soils obtained from Sile (Istanbul city region) and Kitre (Bayburt city region) districts of Turkey. Various soils and polypropylene fiber mixtures were prepared in the laboratory and the engineering properties of these mixtures were observed. The compaction characteristics and the unconfined compressive strength of samples were investigated. This paper illustrates the findings from the laboratory study with particular emphasis on the use of mentioned additive that provide economic benefits, as well as reduced environmental impact.

For soils originating from semi-arid terrains that develop pozzolanic reactivity with additives, the duration of load increment may not reflect the true nature of consolidation behavior when tested with the conventional approach of testing with the loading duration of 24 h. Thus, to assess the consolidation properties of Al-Ghat soil with lime, it is proposed to keep the duration of loading as minimum as possible and it is varied as 0.5, 1, 2, 4, 8, and 24 h. It is observed that the addition of lime significantly affects the compressibility behavior of Al-Ghat soil. Further, at any pressure increment, the final equilibrium void ratio values increase with the increase in duration of loading. The difference in change in void ratio reduces as duration of load increment increases upon lime treatment. When the duration of loading increment is increased from 30 min to 24 h, relatively more curing time is allowed for the pozzolanic reactions to occur, which significantly reduces the resultant difference in decrease in void ratio.

In this study, a numerical solution adopting an elastic visco-plastic model with nonlinear creep function incorporated in the consolidation equations has been developed to investigate the time-dependent behavior of soft soil deposits improved with vertical drains and preloading. The employed elastic visco-plastic model is based on the framework of the modified Cam-Clay model capturing soil creep during excess pore water pressure dissipation. In addition, nonlinear variations of creep strain rate with stress and time and permeability variations during the consolidation process are considered. The developed numerical model is validated against Ska-Edeby test fill with the available long-term settlement and excess pore water pressure monitoring results for the soft clay deposit improved with vertical drains assisted preloading. Practicing engineers can adopt the developed code and guidelines to predict the long-term performance of embankments on soft soil improved using preloading.

In this paper, the Eurocode 2 (EC2) approach for strength and stiffness prediction of concrete is adapted to soil-cement laboratory formulations for jet grouting (JG) and cutter soil mixing (CSM) technologies. In particularly, the EC2 approach performance using laboratory test data at early stages (e.g., 3, 7 or 14 days) is compared with the conventional 28 days' time of cure. As expected, the achieved results show a decrease in EC2 approach performance when test data at early stages are used. However, a slight difference is also observed in EC2 approach performance when test data at 14 days or 28 days are used. This observation allows us to balance the model prediction accuracy and time consuming in the final project and construction work costs.

The utilization of fly-ash stabilizers, fly ash from fluidized combustion and other solid products of combustion, and desulphurization arising during the production of electricity have a good potential for use in the roadbed structures of pavement structures. With a lower density and high shear strength, fly ash reduces the ground subsidence and pressure on supporting constructions during the construction of roadbed structures. In the coming years, an increased focus on the use of these materials can be expected with regard to the continuation of the road infrastructure construction. One of the possible factors blocking the use of some types of fly ashes is their relatively little resistance to repeated contact with water and resulting volume changes. Their water sensitivity is well known. Given thenegative properties of fly ash, which occur mainly in repeated contact with water, it was decided to pay attention to the testing of the resistance of these mixes to the combined effect of freezing and water within the experimental activity. Fly-ash stabilized mixes were designed with the use of ashes from two combustion technologies with different contents of binder and also including the influence of selected chemical additives and binders such as lime hydrated or mineral admixtures such as chemomechanically activated dolomitic lime.

This research explored the performances of different bond-breaking layers installed atop the cement-stabilized bases to offer parameters for structure analysis of pavements with bond-breaking layers and to optimize the selection of bond-breaking layers for the practical road engineering projects. This research tested the bonding stresses and the frictional forces at slab-base interface of pavements under different bond-breaking conditions, as well as the anti-erosion performance of base. This was done through the anti-erosion tests in laboratory and the field tests for mechanical performance of slab-base interface treated with different bond-breaking layers of the Yunfu-Luoding highway project of Guangdong Province. Bond-breaking media applied in this research include the 1 cm emulsified asphalt slurry seal (EASS), geotextile and emulsion wax curing agent (EWCA). The findings from the field tests for bonding stress between slab-base layers indicated that EWCA did better than EASS in reducing friction or bonding stress between slab-base layers. Also, the findings from the anti-erosion tests indicated that under the same other conditions, the specimen covered with geotextile did better than specimen covered with EASS and far better than specimen bond-breaking layer in resisting water erosion. The performance of slab-base interface with different bond-breaking media derived from this research offers scientific reference to pavement design and construction control in the practical road engineering projects.

For a fast treatment of winter distresses, which minimizes the adverse influence of the treatment work on traffic safety and traffic flow, a prefabricated, rollable pavement was developed that is based on a textile-reinforced concrete with short fiber. A high tensile strength and ductility can be expected. Through an oriented design and structuring of the surface, the skid resistance, drainability, and resistance to removal of aggregates can be optimized. This paper provides a basis study on this innovative road surface. With this technique, winter distresses can be removed within a few hours. The new road surface can be opened to traffic as soon as possible. Therefore, it has the potential to contribute to durable road structures and sustainability of road engineering.

Dowel bar retrofit (DBR) is an effective concrete pavement preservation technique to restore the load transfer efficiency at joints of the jointed plain concrete pavement. So far, more than 5 million dowel bars have been installed in the United States. Although the majority of DBR projects were successful, some have had issues, including early failures. Recently, it has been proposed that polyester grout may perform better than conventional DBR grout materials. Polyester grout is a grout using polymerized resin as a binder instead of fast setting concrete backfill material. Compared to conventional grout materials containing high alumina or magnesium phosphate materials, the polyester grout has more flexibility, better adhesion with the existing pavement, and a low viscosity for better consolidation. This paper presents the results of evaluation of performance of US 50 DBR project constructed with polyester grout in 2010 for the California Department of Transportation. In 2012, a team of researchers and engineers conducted visual inspections and nondestructive tests. Core extractions were also performed at a later date based on the visual inspection and non-destructive test results. In the laboratory, the tests included shear bonding strength tests as well as dowel bar pull out tests. The results in both the laboratory and field showed that the polyester grout has worked very well to date.

A preliminary study of rut treatments dealing with the implementation and evaluation stages, focused on cost-effectiveness assessment and function validity by comparing various rut preventive maintenance treatments included microsurfacing, ultra-thin overlay, hot in-place recycling and thin hot mix overlay. The Jiangsu provincial highway network status and major distress were studied based on the statistical analysis of the performance data and maintenance history which was collected from the pavement management system (PMS). The determination method of extended service life (ESL) index of the different preventive maintenance treatments was recommended according to the rut depth used as the control performance indicator. Combined with the ESL value, the benefit-cost ratio (BCR) value using the life-cycle cost analysis (LCCA) method was calculated with different treatment practices, and their effectiveness was compared. The results indicated microsurfacing has the highest cost effectiveness, ultra-thin overlay and hot in-place recycling (HIR) have similar cost-effectiveness levels, wheres thin hot-mix overlay has the lowest BCR value compared to other treatments. The findings support the PMS updating for maximizing both project and network level benefits, combineing the preventive maintenance management system in the near future.

In view of the use of the impact compaction technology in old cement concrete pavement (CCP) reconstruction, ANSYS was used to establish the 3D finite element model (FEM). We combined the actual engineering pavement bending deflection detection and description of the inhibitory effect of reflection cracks in asphalt concrete to describe the reliability of impact compaction technology. The results showed that with the increased number of impact rolling times, lateral cracks appeared first at the lateral boundary of the slab and the bottom of the middle of the slab; then the cracks extended to the top and extended laterally and throughout whole slab finally. With the increase of impact and rolling times, longitudinal cracks appeared first at the top of the longitudinal boundary of the slab, increased with the extension of central lateral cracks in the middle, staggered formed map cracks with lateral cracks, which could be used to inhibit the production of load-type and temperature-type reflection cracks of asphalt concrete overlay. After impact and rolling, the deflection of the test section increased, and the ratio of deflection was 61.2%~94.3%.

Cracking is the most important distress of the steel bridge deck pavement. The distribution of the crack was found to be different in different types of bridges. To assess the bridge structure effect in the crack analysis of the steel deck pavement, a multiscale structure analysis was proposed and performed on the basis of a case study. First, the whole bridge model was analyzed to find the critical segment under critical load combination. The results showed that the critical segment is at the one-fourth span of the bridge. Second, the critical segment model was established using the mixed finiteelement method (FEM), and the critical local plate can be determined. Thirdly, using the submodel technique, the orthotropic steel plate with pavement was modeled and analyzed. The cracking distribution law of the steel deck pavement can be induced by the tensile stress distribution law on the top of the pavement. The results of multiscale structure analysis were then compared to the traditional steel plate model to evaluate the bridge structure effect. Last, some conclusions and suggestions are given for the pavement preservation.

In 2011, a severe flooding event affected the entire state of Queensland in Australia. This resulted in pavement damage to many thousands of kilometers of state and regional council controlled roads. The pavements of the most affected roads consisted of granular layers with multiple sprayed seals constructed over weak, highly reactive natural subgrades. The natural subgrades often exhibited high swelling potential that, coupled with poor road geometry and drainage, often led to large seasonal fluctuation in moisture content of the subgrade. Techniques, such as foamed bitumen stabilization and cement modification of the existing pavement layers, have often been adopted. A range of stabilizing agents, such as foamed bitumen and an array of cementitious stabilizing agents, has been utilized under different circumstances to achieve the best project outcome. Field and laboratory investigations were undertaken to assess the post-flood condition of the road network, as well as to determine the suitability and reactivity of each stabilizing agent to the wide range of base aggregate sources found throughout the network. This paper presents the findings from field and laboratory investigations undertaken on the flood-affected pavements of four regional roads near Ipswich in South East Queensland. These investigations were undertaken to characterize existing pavement materials and to evaluate the performance of existing granular materials stabilized with foamed bitumen or modified with cementitious stabilizing agents. To evaluate the mixes of granular materials and stabilizing agents, the results from tests conducted on samples of existing imported granular materials stabilized or modified with foamed bitumen or cementitious binders were compared against a set of Australian developed mix design criteria. Furthermore, this paper summarizes the advantages and disadvantages of both the cementitious modification and foamed bitumen stabilization techniques and summarises the manners in which these layers were modeled.

In the United States, bottom and fly ashes from waste-to-energy (WTE) plants are typically mixed together before the disposal into landfills to meet the U.S. Environmental Protection Agency (EPA) requirements. Conversely, in many Asian and European countries, the WTE fly ash is not mixed with bottom ash but rather handled as a special waste. In this instance, the bottom ash is often recycled and used as a material in pavement and other similar products. Reuse of the WTE ashes in Portland cement concrete (PCC) and hot-mix asphalt (HMA) may offer a significant contribution to reduce cost for waste disposal, natural resources conservation, and developing sustainable construction. An important factor hindering the acceptance of WTE ashes as construction materials, however, is their uncertain physical and chemical properties. In this study, fundamental properties of the WTE bottom and fly ashes were studied by conducting physical, microstructural, and chemical tests using a scanning electron microscope (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD).