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Transverse cracking is a major distress in asphalt pavements in north-western Oklahoma. Assessment of probable causes of such distresses is helpful to the design of new pavements and maintenance and rehabilitation of existing pavements. In this study, probable causes of transverse cracking were identified using field investigation and a parametric study using AASHTOWare Pavement ME Design. Specifically, non-destructive and destructive tests were performed on two flexible pavement sections, namely US 270 and US 287 in Oklahoma. Also, soil samples and asphalt cores were collected for laboratory testing. The Ground Penetrating Radar results revealed that the disturbance zone was confined within the pavement structure and cracks were generated at the surface and propagated downward at both sites. The Dynamic Cone Penetration and Falling Weight Deflectometer test results indicated that both pavement sections were structurally adequate to support the current level of traffic for 10 years or more, with proper maintenance. The cracking resistance of the asphalt cores collected from both pavement sections was ranked as poor based on the Illinois Flexibility Index Test. The field and laboratory investigations indicated that stiffer and brittle asphalt mixes at both sites resulting from aging during the long service life were primarily responsible for the transverse cracking observed in the field. Also, a large number of thermal cycles with significant difference between low and high temperature, observed from the weather data, was a likely contributing factor. In addition to field and laboratory investigations, a parametric study was conducted using the AASHTOWare Pavement ME Design. The influence of the changes in pavement structural components, material properties and the average hourly temperature on transverse cracking was examined. Binder grade and pavement thickness were found to be the most influential factors. A hybrid approach involving field and laboratory testing and a parametric study using the AASHTOWare Pavement ME Design was found to be a useful tool for assessment of probable causes of transverse cracking in asphalt pavements.

Potential benefits in applying polypropylene fiber to stabilize expansive soils and cement treated bases is already been reported in previous studies. So a critical need exists to incorporate the use of fiber into the Texas Department of Transportation’s (TxDOT’s) Guidelines for Modification and Stabilization of Soils and Base for Use in Pavement Structures. The present paper discusses the results collected from the first experimental test section on FM897 in the TxDOT Paris District. Three 500-ft (152.4m) test sections were constructed with 2 percent cement on FM897 in February 2020 in the north bound lane loaded truck direction which includes a new sandstone base, full depth reclamation (FDR), and control. However, only the new sandstone base and FDR sections were built with fiber. In this project, two types of fibers were used —(a) fibrillated fiber Fibermesh300, and (b) macro-synthetic fiber Enduro 600. The surface and base layers from the new sandstone base section were removed and used for the edge widening area of the FDR and control sections. Based on the laboratory tests, the optimum fiber contents were found to be 0.6 percent and 0.4 percent for a new sandstone base and FDR, respectively. The laboratory Unconfine Compression Strength (UCS) results showed significant improvements (

Due to their high permeability and high strength, pervious concrete piles (PCPs) can improve ground bearing capacity. However, clogging of pervious concrete in practice is a potential disadvantage. To investigate the clogging mechanism of PCPs due to sand piping, a series of laboratory simulation tests is conducted on a developed hydraulic conductivity test system. This testing demonstrates the effects of pervious concrete porosity, grading of fine movable particles, mix ratio of skeleton particles to movable particles, relative density of soil, and distance between PCPs on PCP clogging. The experimental test results show that the hydraulic conductivity of PCP decreases for approximately 70 min and then becomes relatively stable. In addition, it is observed that PCP clogging rarely occurs in cases of low pervious concrete porosity, small movable sand particle size, high sand relative density, and large pile distance. The results also show that measurement of electrical conductivity can be an alternative method of hydraulic conductivity measurement. Based on the test results, preliminary clogging models are proposed.

Traditionally, traffic loading characteristics are collected for pavement design and performance prediction purposes using permanent roadside weigh-in-motion (WIM) stations. However, high installation and maintenance costs associated with these permanent WIM stations dictate that their deployment be mostly limited to major highways, such as the interstate network. Quite often however, pavement damage on high volume rural highways with heavy truck proportions is more severe than anticipated, and there is no effective way of quantifying the traffic loading on these highways. Therefore, this study was conducted to evaluate the potential application of portable WIM systems as a means for bringing the WIM technology to these high volume rural highways. A portable WIM unit was deployed in the Texas overweight corridor in Hidalgo County (Pharr District) near the USA-Mexico border on highway FM 1016 for collecting traffic data for a minimum of three weeks in each direction. The collected traffic data were analyzed to generate traffic parameters such as volume, load spectra, and overloading information both in terms of the gross vehicle weight (GVW) and axle weight. The computed traffic parameters were successful in partially explaining some of the existing pavement conditions on this highway. Overall, the study findings indicated that the portable WIM unit can be used as a convenient and cost-effective means for collecting reliable traffic information for design, analysis, and monitoring purposes. However, proper in-situ calibration of the portable WIM unit at each site is imperative prior to any real-time traffic data collection. Keywords: Traffic data, Load spectra, Truck overweight, Weigh-in-motion (WIM), Portable WIM, Texas overweight corridor

This special issue of the International Journal of Geomechanics contains 10 papers that cover numerical and experimental investigations on various aspects of sustainable civil infrastructures. The topics include the self-healing capability of asphalt, cracking and fracture of asphalt pavement and portland cement concrete, soilimprovement techniques (including compaction and vertical drains), and various foundation systems. There are two papers on asphalt. The self-healing of asphalt mixtures can extend the fatigue life of asphalt pavement. Huang et al. developed a method based on fuzzy evaluation and the analytic hierarchy process for evaluating the self-healing capability of asphalt mixtures. The feasibility and effectiveness of the method were validated by a case study. To understand the mechanisms of material failure is essential for the design and construction of sustainable civil infrastructures. Chen et al. proposed a multiscale numerical modeling approach to analyze the distress of asphalt pavement on steel bridge decks and applied the approach to a case study. Their results highlighted the importance of bridge structure and pavement evenness in the distribution of pavement cracks. One paper focuses on concrete fracture and damage. Xu et al. investigated the spallation failure of fiber-reinforced concrete slabs under impact loading. Their numerical simulations showed that fibers can remarkably improve the tensile strength of concrete slabs and effectively limit the initiation and propagation of cracks. Soil improvement is an important element of sustainable civil infrastructures. Three papers are related to soil-improvement techniques, including compaction and vertical drains. Nie et al. presented an integrated theoretical and case study on anomalous data detection for roller-integrated compactionmeasurement. Their results showed that the proposed bidimensional anomalous data-identification method rendered a more accurate correlation, whereas the proposed neighbor-weighted estimation method improved the precision of compaction evaluation. Two papers are related to vertical drains. Azari et al. applied an elastic–viscoplastic model to model soft soil improved with vertical drains and compared their simulation results with field measurements. Their results showed that the distribution of the overconsolidation ratios in the disturbed zone greatly influenced the viscoplastic strain rates, creep strain limits, and consolidation. Parsa-Pajouh et al. evaluated the efficiency of several proposed formulations for plane-strain modeling of vertical drain-assisted consolidation through an integrated numerical and experimental investigation. By comparing the predicted and measured pore pressures in well-controlled laboratory tests, the advantages and disadvantages of these formulations were discussed. The remaining four papers deal with foundation systems. A better understanding of soil–structure interaction can lead to optimized foundation design and construction, which increase the sustainability of many civil infrastructures. Zhou and Dai presented a new strut-and-tie model for the analysis of force distribution among piles, pile caps, and superstructure components, including struts and ties. Through two case studies, they demonstrated the effectiveness and accuracy of their model. Farouk and Farouk examined the effect of a superstructure’s rigidity on the contact stress and differential settlement for plane two-bay frames. They found that the rigidities of walls and slabs have significant effects on the resultant average contact stresses and the maximum settlements under the footings, which affect the differential settlements. They provided new charts and equations for calculating the average contact stress and maximum settlements under the inner and outer footings for plane two-bay frames. Zhang et al. developed a numerical model to investigate the working mechanism of pervious concrete piles. Their model was validated by a case study. Their results showed that pervious concrete piles can reduce foundation settlement caused by their high stiffness and permeability and, hence, are particularly suitable for reinforcing foundations with low bearing capacity and soils with poor permeability. Yang et al. conducted a numerical investigation on the load-displacement behavior of a reinforced strip footing using a double-yield model. The effects of various parameters, such as burial depth, reinforcement length, and arrangement of two reinforcement layers, were studied. Their results showed that the load-displacement behavior of strip footings simulated with the double-yield model is more realistic than that with the Mohr-Coulomb model, and the optimal burial depth and length of reinforcement obtained from their study agreed well with values reported by previous investigators.

Recent developments of innovative technologies and materials have offered many exciting opportunities for engineers to design and build more sustainable civil infrastructures. Innovation may come in the form of, e.g., better material performance, lower production costs, improved construction and monitoring techniques, reduced health, and environmental impacts. The use of new materials or technologies in an infrastructure project requires a rethink of the existing design philosophy and construction processes. Collaboration between all parties involved (owner, design consultant, contractor, and local authority) is also necessary. Pilot field, laboratory, or numerical studies are often, though not always, undertaken to evaluate the performance of the new technique prior to full-scale applications. This special issue covers a wide range of contemporary issues in the field of geotechnical, pavement, and bridge engineering. The aim of the special issue is to share ideas, knowledge, and experience on the recent developments of innovative materials and technologies for sustainable civil infrastructures. This special issue includes 12 papers that have been subject to the same rigorous peer review process as regular articles in this Journal. There is one paper in this special issue on the sustainable development of bridge infrastructures. Mehrabi discusses advances in evaluation, health monitoring, and rehabilitation of cable-stayed bridges. In addition, the author presents a unified approach for inservice evaluation and cable replacement design of cable-stayed bridges. The author introduces its first application to the Luling Bridge in Louisiana. The cable replacement design accommodates an extraordinary construction sequence to address constraints on space and traffic flow. Temporary cables minimize stress variation and allow for the live load without restriction. The new cable system allows individual strand installation and tensioning, and is expected to facilitate future inspections and replacement. The bridge evaluation process and cable replacement design is unique and successful, which is useful for sustainable development of all cable-stayed bridges. There are three papers in this special issue that discuss the use of innovative techniques to reduce the risk of damage to key infrastructure. The first paper by Huang et al. discusses the use of a global positioning system (GPS) to monitor the Shuping landslide in the Three Gorges Reservoir in China. More than 10 years of ground surface movement data are presented. The triggering factors for surface movement are correlated with fluctuations of reservoir water levels and rainfall records. This important case history shows that long-term and near-real-time monitoring is invaluable for the understanding of landslide movements and their hydrological triggers. On a similar note, in the second paper, Yang discusses the use of remote sensing techniques (satellite images and aerial photos) to determine the probability of road interruption due to landslides for different rainfall return periods. Rainfall-induced landslides are common in Taiwan and often result in road closures. Yang develops a validated landslide prediction model using logistic regression for a rural township in Taiwan. The study area is mainly hilly and mountainous and covers five main roads and 13 villages. The model provides the local authority a useful means to prioritize road maintenance works and to select emergency evacuation routes with lower probabilities of landslide occurrence. High-speed railway (HSR) bridges are important infrastructure in many countries. To ensure their safe operations during the construction of new underpass bridges, in the third paper He et al. describe a risk assessment method and an automated early warning system and their application for a project in Tianjin City, China, where a new bridge was constructed to cross the Beijing-Tianjin Intercity Railway. During construction of the underpass structure, settlement and deformation of the HSR bridges were closely monitored and compared with the predetermined threshold values. This successful case history demonstrates the importance of risk control for the protection of existing key infrastructure. There are three papers in this special issue that discuss different aspects of innovative pavementmaterials andmanagement. The first paper, by Wang et al., develops a fast treatment of winter distresses by using a 1-cm-thick prefabricated rollable pavement based on a textile-reinforced concrete. They find that this innovative prefabricated rollable pavement has high mechanical resistance and positive texture characteristics. With this technique, winter distresses can be repaired and the roadway can be opened for traffic within only a few hours. This technique has the potential to prolong roadway life and enhance sustainability. In the second paper, Steyn et al. investigate the required properties of foamed concrete for possible implementation as an alternative to engineered material arresting system on airports. As part of the investigation, plate load tests, unconfined compressive strength tests, stiffness tests, and density evaluations are carried out on the foamed concrete, using a range of plate sizes that represent different contact areas of tires for vehicles entering an arrestor bed. They find that foamed concrete can be used as an arresting material because the compressive strength and energy absorption of foamed concretemet the requirements. Foamed concretewith densities of 600 and 800 kg=m allow formore settlement, while the stress-deformation relationship is very similar to that ofmaterial currently used in arrestor beds. The third paper, by Chang and Lin, explores the building information modeling to be used in Taiwan as a basis for developing the concept of road information modeling (RIM) for underground pipeline management. Residents in urban areas rely on a complex and dense network of underground pipelines. Underground infrastructure presents unique challenges for

The placement of an asphalt overlay is the most common method to rehabilitate existing concrete pavements. Reflective cracking, however, has been a serious problem with asphalt overlays for a long time. To prevent reflective cracking, it is critical to evaluate existing concrete pavements and identify the joints/cracks with poor load-transfer efficiency (LTE) before placing an asphalt overlay. The most common equipment for this evaluation is a falling weight deflectometer (FWD). However, FWD testing is conducted only at discrete points and is time consuming. It is desirable to use the rolling dynamic deflectometer (RDD) that can continuously characterize each slab and all joints and cracks (e.g., LTE). The RDD was developed in the 1990s at the Center for Transportation Research in Austin, Texas. The RDD is one of the few operational rolling deflection systems that provide continuous data to make project level decisions on rehabilitating concrete pavements. In contrast to the FWD, no RDD data analysis software is available. This paper discusses RDD data interpretation and its application on evaluating existing concrete pavement for asphalt overlays. First of all, some basics of RDD deflection data interpretation are discussed. Several common patterns within the RDD data are identified, and associated interpretation and limited verification are presented in this paper. The RDD deflection data measured before an asphalt overlay on Interstate Highway-20, Texas, and the observed asphalt overlay performance (in terms of reflective cracking) are then presented, and the relationship between RDD deflection and reflective cracking rate is further investigated. Finally, guidelines for evaluating existing concrete pavements using RDD are proposed.

A stretch of State Highway (SH) 6 in Texas has been experiencing poor ride quality problems caused by continuous pavement swelling and heaving. Because of this, the Texas Department of Transportation (TxDOT) Waco District annually spent hundreds of thousands of dollars to overlay the pavement to keep it smooth. This study is motivated to identify the root causes and solutions to the critical problem. During the forensic study, a systematic approach is employed, which includes nondestructive and destructive tests. On the basis of the overall test results, it is revealed that the problem was initiated within the lower portion of the pavement structure (i.e., subgrade) rather than in the upper pavement structure (i.e., asphalt concrete and flexible base). It was further found that the major factors contributing to the subgrade problem include (1) swelling soils, (2) water penetrating into the expansive clay soils, (3) high organics content in the soil, (4) loss of strength of the lime stabilized laye...

Density criterion for base materials is the most common practice in quality control and quality assurance for pavement construction. However, cases in which the base material has met the density requirement but turned out to be the cause of a premature failure exist. It means meeting the density requirements would not prevent the premature failures from occurring. Field studies indicated that these base materials are found to be either too weak to provide sufficient base support or too brittle, which causes cracks in base layers which in turn leads to secondary damage in other pavement layers. This paper documents the pavement layer moduli obtained from eight forensic investigations spanning 10 years. Falling-weight deflectometer and dynamic cone penetration tests were conducted to determine the layer moduli on sections that were either too weak or too brittle. In some cases, laboratory tests were performed to evaluate the base materials’ reactions to the stabilizers (lime or cement) and base susceptibili...

A forensic study was conducted to investigate the premature cracking distress on an ongoing construction project on State Highway (SH) 24. Transverse cracks occurred at approximately every 9–15 m (30–50 ft) along the 9.6 km (5.9 mi) project. The field tests involved both destructive tests, including trenching and coring, and nondestructive tests, including falling weight deflectometer (FWD) and ground-penetrating radar (GPR) tests. The laboratory tests mainly included cement-treated base material and asphalt mixture material series tests. By integrating all the test results, it was concluded that the premature cracking was originating from the cement-treated base (CTB). Although CTB is not a new concept in pavement construction, stabilization of base materials is a complex process, which, if not handled properly, may lead to premature failures. The two primary factors that contributed to the premature failure are (1) an excessive amount of cement in the CTB, and (2) a high moisture content when the CTB wa...

To prevent premature failures of rehabilitated concrete pavements, transportation authorities need tools to characterize the prerehab pavement condition of its load carrying capacity, and to determine the resistance of the overlay material to underlying crack/joint movements. Two quantitative methods, the rolling dynamic deflectometer (RDD) and overlay tester (OT), along with field performance data were employed in rehabilitation studies involving reflective cracks. The RDD is able to continuously assess vertical differential movements at joints/cracks that represent the potential for reflective cracks on existing pavements. The OT has the ability to determine the resistance of the overlay material to underlying crack/joint movements. The RDD W1−W3 deflections were used to determine areas that have a high potential for reflective cracking due to poor load transfer across joints and cracks. This paper documents results from the RDD and OT on the following five rehabilitation projects: (1) SH225; (2) US96; ...

As part of a national pool funded study 208 on pavement subgrade performance, 12 full-scale test sections (four soil types and three moisture contents) were constructed and tested under the heavy vehicle simulator (HVS) loading. This paper presents the HVS results on two of the four soils tested: AASHTO Class A-2-4 and A-4 soils, respectively. From the results, it was found that the pavement subgrade performance is a function of soil type, moisture content, and applied stress condition. Additionally, this paper also evaluated the current mechanistic-empirical pavement design guide (MEPDG) subgrade rutting (permanent strain) model through comparing with the actual measurements under the HVS loading. It was found that the MEPDG subgrade permanent strain model needs further improvement, and that a single performance model may not be universally applicable to different subgrade soil types. Consequently, a new permanent strain model for each soil type was developed in this paper, based on the HVS results, and that yielded better predictions. With further validation and field calibration, the proposed models offer promising potential to accurately predict rutting behavior of these two soils.

The nondestructive mapping of anomalies and voids under roadway pavements is critical to highway authorities because of the potential loss of support that would lead to safety hazards. 400 MHz ground-coupled penetrating radar (GCPR) was used in this study to characterize the subsurface conditions of three roadway pavements (SH359, IH40, and U.S. 290). The extents of the anomalies in horizontal and vertical directions were visible in GCPR images. Coring, boring, and lab testing were performed to verify the settlement and source of the moisture on SH359. The source of the moisture was from the leaking water pipe, as indicated by the high chloride and chlorite contents. A 1.8-m deep void ( 3.8 m3 in volume) under IH40 and a 1.8 m×4.6 m×3.7 m ( 30.6 m3 in volume) void under U.S. 290’s reinforced concrete pavements were successfully identified by GCPR and verified by field boring and coring. Fortunately, the voids near the drainpipes were detected by GCPR in time. Otherwise, the void would have increased in ...

A section of jointed concrete pavement on U.S. 75, which was built from 1982 to 1985, in the Paris District of the Texas Department of Transportation (TxDOT) experienced severe pumping and settlement, even though two types of treatment (full depth repair and polyurethane foam injection) were performed. An extensive field investigation was conducted using ground penetrating radar, falling weight deflectometer, dynamic cone penetrometer, and coring to identify the causes of the continued pumping and settlement problems, and develop an optimal repair strategy. The pavement evaluation included tie bar condition, load transfer efficiency (LTE) at transverse and longitudinal construction joints, and base support conditions. Some of the tie bars failed in shear due to corrosion, which resulted in substantially low LTEs (

An investigation was conducted to determine the root cause of the premature pavement failure. The premature pavement failure occurred in the form of rutting and alligator cracking. Although the affected portion was repaired by removing and replacing the top 75-mm asphalt concrete (AC), the repaired AC experienced recurring rutting and alligator cracking in a few weeks. Through extensive field and lab testing, it was found that the weak base is the root cause of the premature failure and the brittleness of the AC is secondary. However, both the base and AC were built according to plan and met the current material and field density requirements. It was concluded that density alone for construction quality control is not sufficient, as it was not able to protect against premature failures from occurring. Although there are many different ways to minimize premature failures, an immediate action is to include proof rolling in construction quality control. Proof rolling has been used with success to ensure proper compaction and to locate unstable areas, as the stability is greatly influenced by the degree of densification achieved during compaction.

Spalls and wide cracks represent functional and structural distresses in portland cement concrete pavement. Traditionally, these distresses were repaired by partial depth repair (PDR). The performance of PDR varies substantially. Two types of polymeric patch materials, Material-A and Material-B, were used to repair spalls and cracks. Material-A was used to repair spalls in continuously reinforced concrete pavement. It provided quite satisfactory performance for more than 6 years. Material-B was used to repair cracks in jointed concrete pavement. Its performance was satisfactory when applied to stable slabs. Compared with full-depth repair (FDR), PDRs utilizing polymeric patch materials is much more cost effective, and PDR takes much less time than FDR. It was found that chip-and-patch method would work as well as saw-and-patch method as long as the repair limits include all the delaminated areas.

Where faulting takes place due to the absence of dowel bars and inadequate subbase support in jointed concrete pavement (JCP), dowel bar retrofit (DBR) is used to improve load transfer efficiency (LTE) and to prevent further faulting of slabs at transverse joints. Even though DBR generally improves LTEs and overall performance of JCPs, not all DBR projects have been successful. Faulting reoccurred within 2 years after DBR treatment on US59 in Texas. An investigation from the cores taken in the project revealed excessive voids under a dowel bar due to poor consolidation of the grouting material. A laboratory investigation was performed to determine the most critical factors for adequate consolidation of grouting materials in DBR. Typical rapid-setting grout materials widely used in DBR were selected and full-scale specimens were made for evaluations. Four testing variables for consolidation performance were investigated: time of placement after mixing, vibration time, slot width, and maximum aggregate size. Maximum aggregate size and slot width were not critical factors for consolidation performance of grout. The most significant factor was vibration time. Twenty s of vibration is recommended. Placement time was also an important factor, with grout materials placed after initial set performing poorly. Delayed placement of grout materials without vibration led to the most voids under the dowel bars.

A forensic study was conducted to investigate the premature pavement failure of heaving and cracking on the north bound lane of SH6 and to determine (1) the causes of the heaving and cracking; (2) the severity and extent of the problem; and (3) a prevention strategy. Ground penetration radar (GPR), falling weight deflectometer (FWD), dynamic cone penetrometer (DCP), and soil boring and laboratory tests were conducted. Soil maps provided by the Natural Resource Conservation Service (NRCS) and the electrical resistivity tomography (ERT) were utilized to locate areas that may have similar problems for the ongoing project. It was concluded that the heaving was caused by high organic content in soils. The low pH of the lime treated subgrade layer indicated that the lime stabilization was ineffective. This was due to the high concentration of organic matter. FWD and DCP results indicated that the heaved/cracked areas are losing structural load support. Approximately 84% of the bumps/dips detected by the profiler were also detected by the GPR. Based on the GPR results, it was estimated that about 1.2 miles of the roadway may have potential heaving in the future. Although it is not a standard practice to determine the organic content of soil for new construction, it is critical to determine the organic matter through soil boring and laboratory testing in the suspicious areas. It was found that the soil maps provided by the NRCS yielded a reasonable estimate, and can be used as a screening tool. All five locations (O1 to O5) identified by ERT were verified by boring and laboratory tests to have high organic content (1.9 – 3.3%). Boring results indicated that ERT was able to map the soil strata and could differentiate between sandy and clay soil types. Although ERT was able to identify the anomalies with high organic contents, and the results were confirmed by boring and laboratory testing, additional work is needed to refine the procedure.

As agencies continue looking for cost-effective methods to rehabilitate deteriorated jointed concrete pavement (JCP), rubblization using a resonant breaker has been experimented by the Shanghai Municipal Roadway Authority (SMRA). It was demonstrated that rubblization using a resonant breaker offers a viable option for the SMRA because the rubblized pavement sections have been performing very well with no visible distress. Based on field observation for a typical hot mix asphalt concrete (HMAC) overlay on a nonrubblized JCP, it was found the treatment normally would have reflective cracking for the same overlay thickness in the first three years. Besides the cost advantage over the reconstruction, a resonant breaker also had yielded the minimum disturbance during the rubblization. It was observed that it was very effective to use water during compaction on a rubblized JCP surface to improve compaction efficiency and to control dust. Furthermore, there is no need to apply a prime coat before the HMAC overlay, as there was no detrimental effect that could be identified. The average rubblized JCP moduli were found to be 1,323 to 1,375 MPa, which are within the range reported in the literature. It was believed that there were high possibilities to increase rubblized JCP moduli without sacrificing the performance by increasing the particle size, because a reduction of 200 mm of HMAC was observed when rubblized JCP increased from 345 to 3,445 MPa at a subgrade modulus of 138 MPa and traffic of 30 million ESAL. However, further research is needed to optimize the rubblized JCP moduli in an attempt to reduce overlay thickness without creating reflective cracking.

In Texas, many miles of plain jointed concrete pavement (JCP) were constructed without proper load transfer devices such as dowels. After a number of years of service, some JCP sections without dowels showed distresses in the form of faulting at transverse joints. Some of the sections were designed in accordance with the AASHTO 1986 Guide, which required 50–75 mm thicker slabs in exchange for not using dowels. This pavement design did not work, with faulting at transverse joints that cause poor ride. Dowel bar retrofit (DBR) was performed on four projects to restore the pavement condition. Overall, DBR restored load transfer efficiency and resulted in improvement of ride quality. Even where the subbase stiffness is 5–10 times less than the minimum value required for proper performance of JCPs, properly installed DBR effectively restored pavement condition with minimum faulting after decades of service. Therefore, it indicated that DBR is able to minimize the faulting even where there is poor base/subgrade...

After only 2 months in service, the frontage road of US 290 developed a series of depressions that caused a very poor ride. The main cause of the premature failure was attributed to disintegration of the cement treated base (CTB) layer. This was attributed to two primary factors: (1) a very coarse gradation of the aggregate used in the CTB layer which produced a mix that was prone to segregation during placement; and (2) the CTB layer was placed in two lifts, which were not well bonded together. Another contributing factor was the lack of bond between the CTB and the hot mix asphalt (HMA) surface layer. Secondary factors include high air voids in the HMA layer and low HMA layer thickness. The material, when prepared carefully in the lab at the design cement content, passed the strength requirement of 2.07 MPa. But this coarse mix appears to have been difficult to place correctly in the field. The coarsely graded aggregate used on this project appears to be prone to segregation, either during placement or compaction. The ground penetration radar results (with confirmation by core samples) indicated that most of the problems were at the bottom of the upper CTB lift. The CTB was placed in two lifts and very poor condition was found between the two CTB layers. This problem was coupled with a thin, porous, and poorly bonded HMA layer that permitted moisture to enter the CTB layer. Similar failures have also been reported recently on other CTB projects in Houston.

This paper presents three field projects to illustrate the integrated approach to forensic investigations of roadway pavement failures used widely in Texas. In each case, the combined ground-penetrating radar (GPR) and falling weight deflectometer (FWD) data were extremely useful for identifying contributing factors, such as stripping in the hot mix or localized areas of wet or weak base. Dynamic cone penetration (DCP) is used for validating problems with base and subbase layers. Laboratory tests are often required to complete the investigation, especially if the repair strategy calls for in-place recycling of the existing structure. The extent of stripping and high porosity that caused delamination for Projects 1 and 2 was detected by GPR and verified by core samples. GPR, FWD, DCP, and field soil samples all showed indications that the existing base on Project 1 was wet and the stiffness was only about one-third that of a typical flexible base in Texas. FWD data demonstrate that the pavement structures for Projects 1 and 2 were inadequate, so a rehabilitation strategy was selected that included structural strengthening. In Project 3, GPR, lab density, and permeability tests indicate that the dramatic pavement failures were attributable to moisture entering the base through a poorly compacted asphalt concrete layer and poor longitudinal joints. The base material was found to be highly susceptible to moisture and did not meet the Texas Department of Transportation's compressive strength requirements when subjected to capillary soaking. The repetitive triaxial test results revealed that the stiffness and load-carrying capability became inadequate when the base materials were exposed to moisture. The pavement structure had been totally replaced in 2004.

This paper presents the results of several investigations to identify the underlying causes of longitudinal cracking problems in Portland cement concrete (PCC) pavement. Longitudinal cracking is not intended and detrimental to the long-term performance of PCC pavement. Longitudinal cracking problems in five projects were thoroughly investigated and the findings indicate that longitudinal cracking was caused by: (1) late or shallow saw cutting of longitudinal joints; (2) inadequate base support under the concrete slab; and (3) the use of high coefficient of thermal expansion (CTE) aggregates. When the longitudinal cracks were caused by late or shallow saw cutting of longitudinal joints, cracks developed at a very early stage. However, when there was adequate base support, the longitudinal cracks remained relatively tight even after decades of truck trafficking. Another cause of longitudinal cracking was inadequate base support, and cracking due to this mechanism normally progressed to rather wide cracks. Some cracks were as wide as 57 mm. Evaluations of base support by dynamic cone penetrometer in areas where longitudinal cracks were observed indicate quite weak subbase in both full-depth repaired areas and surrounding areas. This implies that the current requirements for the subbase preparation for the full-depth repair are not adequate. Another cause of longitudinal cracking was due to the use of high CTE aggregate in concrete. Large volume changes in concrete when coarse aggregate with high CTE is used could cause excessive stresses in concrete and result in longitudinal cracking. To prevent longitudinal cracking, attention should be exercised to the selection of concrete materials (concrete with low CTE) and the quality of the construction (timely and sufficient saw cutting and proper selection and compaction of subbase material).

The fundamental mechanisms leading to the development of reflective cracking are differential movements from the supporting pavement structure. In this study, the deflection profiles collected using the rolling dynamic deflectometer (RDD) were used to determine the threshold values for reflective cracking. This provides a quantitative method to determine the severity of the cracks (or joints), which controls the potential for reflective cracking. Three different deflection parameters were considered: (i) sensor 1 deflection (W1), (ii) differential deflection between sensor 1 and sensor 3 (W1-W3), and (iii) multiple of baseline deflection value. The reliability concept was also incorporated such that pavement engineers can select criteria (based on predefined confidence levels) to identify locations where reflective cracking is likely to take place. Threshold values were determined from a 4 year study conducted along US Interstate Highway 20 (IH-20), and case studies from overlay projects along State Highway 73 (SH-73) and US Highway 59 (US-59) were investigated to verify the proposed threshold values. Based on the findings in this study, the RDD can identify problematic areas but can also be used to optimize the rehabilitation strategy. As evident from the SH-73 and US-59 projects, the W1-W3 deflection and 2.5× baseline deflection are better criteria than W1 deflection alone.Key words: rolling dynamic deflectometer (RDD), reflective cracking, jointed concrete pavements, continuous deflection.

This paper describes a successful failure analysis to determine the causes of loss of backfill sand from a mechanically stabilized earth (MSE) wall, and cracks on the concrete approach slabs on top of it. The Texas Department of Transportation was concerned that the cracks on the approach slabs may be related to the excessive loss of backfill from behind the MSE walls, and that the embankment structure may be unsafe due to potential voids under the concrete slab. Several cubic meters of sugar sand had washed out of the wall and deposited adjacent to the paneled walls. A series of destructive and nondestructive tests were carried out to determine the causes of the problems. It was found that the cracking of the approach slab and the loss of backfill were unrelated. Suggestions for resolving both problems were made based on this study.

A forensic study was conducted to identify the cause of the premature cracking on three recently completed projects that were built with the same design. Nondestructive [ground penetration radar, falling weight deflectometer (FWD), GeoGauge, and Portable FWD], nuclear density gauge, dynamic cone penetration, and extensive laboratory tests were performed. It was found that the initial stiffness of the treated base was found to be excessively high by FWD backcalculation. Some sections of the backcalculated base moduli were over 20.7 GPa. This indicates that the layer is excessively brittle for a base material, similar to lean concrete. Six specimens (that were made without a mellowing period) exhibited cracks. There was no cracking for six specimens that had two days of mellowing. It was concluded that the culprit of the transverse cracking in the main lanes was the shrinkage of lime treated base layers. The longitudinal cracks are related to the edge drying and the transverse cracks are related to the insufficient mellowing period. Based on the findings of this study, the District implemented a 2-day mellowing period for Quicklime treated caliche base. Three newly constructed pavements (age 8, 5, and 2 months) were surveyed. No cracking can be observed so far, and the District thinks the cracking problem has been mitigated by the 2-day mellowing period. Without the mellowing period, cracking had normally occurred 1 to 2 months after construction.

Diamond Grinding (DG) has been utilized by various districts to improve skid resistance (reduce accidents and fatalities) and improve ride quality (reduce International Roughness Index [IRI]), with the added benefit of reducing tire/pavement interface noise. The Department has used DG on both Jointed Concrete Pavement (JCP) and Continuously Reinforced Concrete Pavement (CRCP). This study performed crash accident analysis both before and after DG on a recent project section. After the completion of DG, the occurrences had reduced by approximately 62% and 46% for fatalities and incapacitating injuries, respectively. There was an average IRI reduction of approximately 44 in./mi. (0.70 m/km), or 40%, immediately after treatment. This study also analyzed eleven projects 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 (SN) increased 5.6, or by about 30%. Depending on the existing pavement conditions, the range of the increase in SN varies from 1–18. Similarly, there was an average IRI reduction of approximately 60 in./mi. (0.95 m/km) immediately after the DG, or about 40%. Depending on the existing pavement conditions, the range of IRI reduction varies from 20–122 in./mi. (0.32–1.94 m/km), or 17–57%. For deterioration rate under the effect of factors such as time and traffic, each year the SN decreases by approximately 2.0 and IRI increases by approximately 1.7 in./mi. (0.03 m/km).

The main objective of the forensic study was to identify the cause(s) of the pavement failure on a temporary detour of an interstate highway in Austin, Texas. Ground penetrating radar (GPR), falling weight deflectometer (FWD), coring, trenching, and comprehensive laboratory tests were performed. It was found that the main cause of the premature failure was attributed to material and construction practices. The base material used on this project did not meet the Triaxial class 1 requirement; it tested as a class 2.3 material. The base material was found to be highly moisture susceptible; it did not meet the Texas Department of Transportation's (TxDOT's) compressive strength requirements when subjected to capillary soaking. In addition, the repetitive triaxial test results revealed that the stiffness and load-carrying capability and resistance to permanent deformation became inadequate when the base material was exposed to moisture. It is believed that moisture entered this pavement primarily through poorly compacted AC layers and longitudinal joints. Cores taken in March 2004 from the original type B and C layers confirmed that the majority of cores have air voids exceeding 9%. The lower type B layer was also badly segregated and debonded from the upper type C layer at some locations. GPR results also indicated that the joints in the pavement were excessively porous. Further tests on the recovered binder for the type B layer indicated that the binder was prematurely aged, most probably from overheating during production.Key words: pavement failure, forensic, ground penetrating radar (GPR), falling weight deflectometer (FWD), laboratory testing.

This paper focuses on the cause, possible solutions, and future prevention of pavement heave at a new construction project. We speculated that heaving on the east side of the project was caused by a reaction between the lime stabilizer and minerals in the soil. Because of a difference in soil chemistry, the west side of the project (which was still under construction) did not show evidence of heaving. A forensic investigation was initiated to test our hypothesis. The findings of the investigation concluded that the cause of the heaving on the east side of the road was related to the formation of the expansive mineral, ettringite. Ettringite formed due to the reaction of the lime stabilizer with seams of high sulfate soil on the east side. Laboratory testing did not find any effective stabilizer for the high-sulfate soils on the east side. Therefore, reconstruction would involve removing and replacing the treated layer with a select material that has less than 2,000 ppm sulfates. Test results indicate that there was no threat of sulfate heave on the west side. District personnel had performed the field conductivity tests to evaluate and monitor the concentration of the sulfate content on the remaining project. The treatment of 3%/72-h mellowing period/3% lime treatment was employed on the west side. The whole project has been completed for 1 year and no heave has been observed.

Fourteen Texas SPS-3 test sites were studied to determine the effectiveness of preventative maintenance treatments. These sections were built on four highway classifications (IH, US, SH, and FM) in different climates and with different levels of traffic and subgrade support. Almost all 14 SPS-3 sites were given preventative maintenance treatments (thin overlay, slurry seal, crack seal, and chip seal) in Fall 1990. The distress score concept used by the Texas Department of Transportation (TxDOT) was adopted in this study to judge the effectiveness of preventative maintenance treatments. TxDOT has used this concept since the early 1980s, though the utility factors have been revised few times. The distress score quantifies the visible surface wear due to traffic and environmental influences. Only very few sections experienced premature failures on the SPS-3 sites in Texas. In many cases, superior underlying pavement conditions have been found. The chip seal has the most sites in which it is rated the best pe...

The Specific Pavement Study1 pavement test section on US281 in south Texas comprise the largest Strategic Highway Research Program experimental site in the United States. The project was opened to ...

This forensic study is unique in that it involves a pavement warranty specification. Extensive field and laboratory testing was conducted to determine the cause(s) of longitudinal cracks observed on the surface. Four trenches were cut and removed to allow more testing on top of each pavement layer. The tests found that the stiffness of the foamed asphalt base is higher than that of a typical flexible base. However, the subgrade modulus is low compared with the average subgrade modulus in Texas. Water seeped into two trenches (dug into the road where there were surface cracks) within 20 min of digging. No water was observed in the other two trenches, where there were no surface cracks. The two trenches with surface cracks have lower base density and higher base moisture content than the two with no surface cracks. Based on observations of the trenching and coring operations, the same surface cracks have been detected in the base layer. Cracks up to 150 mm into the base layer have been observed. Although cracks have been observed in the base (and they can be related to lower stiffness and higher falling weight deflectometer deflections), it is difficult to determine if the cause of surface cracks is due to the base layer alone. It is difficult to prove if the layer is responsible for the failure, except by properties listed in the specification. One faulty pavement layer can easily cause the failure of other layers. For warranty purposes, layer-specific failure criteria should be clearly outlined. The base did not meet the gradation specification. The field material was substantially finer than specified. While some specifications may have been violated, there is little evidence to show that the cause of the longitudinal cracking is primarily related to the foamed-asphalt-stabilized base.

Transportation infrastructure plays a key role in strengthening economic development opportunities while promoting a better quality of life. Funding challenges are always an issue. Transportation authorities are seeking design innovations, new materials, robust construction, and maintenance technologies to preserve and extend the life of transportation infrastructure because one of the primary objectives of transportation authorities is to provide safe transportation facilities for effective and efficient movement of people and goods. Any decision taken in the conception and construction stages has a significant economical and environmental impact. Consequently, cost reduction is always a key concern of researchers and practitioners worldwide. Cost reduction is not only measured by the reduction of initial costs, but by various other aspects, such as the application of appropriate procedures to increase the life cycle of a project, the use of sustainable materials, the optimization of maintenance strategies and the development of monitoring techniques. This special issue includes 11 peer-reviewed papers that were solicited by the organizing committee of the Geohunan International Conference 2011 from conference presenters. The Geohunan International Conference 2011 provided a showcase for recent developments and advances in design, materials, construction, and maintenance of transportation infrastructure. The conference offered a forum to discuss and debate future directions for the 21st century. It covered a broad array of contemporary issues for professionals involved in pavement, geotechnical, and bridge engineering. There are four papers in this special issue that discuss different aspects of pavement engineering. The first paper, by Steyn and Briedenhann, analyzes the poor performance of surfacing seals where the road is under a bridge. The authors found that because of the low temperature under the bridge during construction, rocks were lost due to smaller rock embedment depth. The authors propose to alleviate the problem by analyzing the potential decreases in surface temperatures during the planning phase and specifying localized increased compaction of the surfacing seal during construction. In recent years, transportation authorities and asphalt industries have explored warm-mix technologies as a means to reduce the mixing and compaction temperatures of asphalt such that energy consumption, emission, and air pollution can be reduced. In the second paper, Xiao, Amirkhanian, and Zhang present a comprehensive laboratory investigation to determine the influences of nonfoaming additives on asphalt binders. The authors found that nonfoaming additives can reduce the viscosity value of asphalt binders and thus decrease the mixing and compaction temperatures such that the performance of asphalt mixes is not sacrificed. Due to increasing traffic volume, and heavy axle loads, many highway pavements in China have premature failures before they reach the designed service life. The third paper, by Wei, Wang, and Ma, explores the perpetual pavements in China to last for 50 years without requiring major structural rehabilitation or reconstruction and needing only periodic surface renewal to address surface distresses. To calibrate and validate the authors’ concepts, the authors instrumented the perpetual pavement sections and compare the measured pavement responses under various axle loads and pavement temperatures to the theoretical model using Monte Carlo simulation techniques. Early or delayed joint sawing may cause either pavement raveling or random cracking. In addition, early opening of a pavement to traffic may also result in premature concrete deteriorations, while delayed opening of a section of pavement to traffic is costly. The fourth paper, by Ge, Wang, and Gao, applies an integrated model Finite Element Modeling Laboratory (FEMLAB, now called COMSOL Multiphysics) to optimize concrete mix design, select concrete placement temperature, and arrange paving time for the optimal concrete construction and strength development under specific environmental conditions. The following two papers are dedicated to soil influences on infrastructure performance. Problems related to loess soils or other unstable soils are highly correlated to climate. Techniques that reduce the vulnerability of soils are quite important. There are two common treatments to reinforce a soft foundation. One is enhancing the soil strength, for example, vacuum preloading and surcharge preloading. The other is installing structures with high stiffness into the soil. The paper by Yu and Yang presents a framework to correlate the cone penetration test (CPT) cone-tip resistance with the local shaft capacity of open-ended steel pipe pile in sand. Effort is made to develop a modified framework to correlate the soil-squeezing effect to the degree of soil plugging. Among the in situ tests, the cone penetration test has been preferably used in the development of the relationship between the cone resistance and pile capacity. Lv, Liu, Ding, and Kong investigate the performance of an X-section cast-in-place concrete (XCC) composite foundation based on the load-settlement curves, axial force and side friction distribution, pile-soil load sharing, pile-soil stress ratio, the sharing of side resistance and end bearing capacity by field tests on an XCC single-pile composite foundation. The authors found that the XCC pile can significantly increase ground bearing capacity. Landslides are often affected by climate. It is important to conduct theoretical studies regarding this matter. It is preferable to undertake such studies in specific zones, depending on geologic conditions, terrain, and climate. The paper by Bai, Du, Kuang, and Cheng describes a risk-warning method and system related to the management of loess engineered slopes. In the following paper, Yang, Shen, Huang, Lee, Cheng, and Chen use the probability maps of landslide occurrence to predict road closure. Road closure attributed to landslides may cause large economic impacts and delay evacuation in case of disasters. Finally, three are papers dedicated to other aspects that can enhance economical optimization. Considerable work has been done developing models to facilitate the planning of earth-moving operations. Carefully planning services between construction sites and landfill sites is an important but complicated task. Lin, Hsie, Hsiao, Wu, and Cheng develop computer simulation methods and genetic algorithms, with the objective of minimizing the time for constructing an optimal dispatch model to implement a more suitable schedule for operating truck fleets. This paper presents a systematic approach for modeling the process of dispatching earth-moving trucks. The paper by Li and Zhang focuses on re

The smoothness of the pavement surface approaching a Weigh-in-Motion (WIM) scale directly affects the device’s ability to accurately estimate static loads from measured dynamic forces. Lack of smoothness creates difficulties in reducing the weighing error to an acceptable level. Efforts were made in this study to determine appropriate values of profile length and roughness of the WIM approach. Roughness data for 19 WIM sites across Texas were collected, and the corresponding calibration records from those WIM sites were employed to verify the smoothness guidelines proposed by AASHTO MP 14 and ASTM E1318. Since there are multiple lanes at each WIM site, a total number of 70 profiles were collected. Based on the calibration records from the WIM sites and field roughness measurements, it was found that the upper threshold value of Long Range Index (LRI) of AASHTO method MP 14 should be adjusted in order to screen out the locations that yield unacceptable weighing error. The lower threshold value was found to be unnecessary, because more than 90 % of WIM sites yielded acceptable weighing error even when they exceeded the lower threshold value. The LRI is preferable to the Short Range Index (SRI) as it matched well with the field WIM calibration results. Based on the 70 profiles used to determine appropriate lengths, a profile length of 25.8 m preceding the WIM is found to be sufficient. That is the length required to obtain a valid LRI, according to AASHTO MP 14. The ASTM E1318 requirement of 60 m is too conservative. It is concluded that an LRI of 1.74 m/km for the 25.8 m leading up to the WIM is the only critical factor in AASHTO MP 14 and is the limit recommended.