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Thermally induced stresses can build up in rigid pavements without pressure relief joints. The pressure created becomes a problem for adjacent structures such as bridges. The pressure can cause the pavement to push on the bridge and close the bridge expansion joints. This sets the stage for additional distress if not repaired quickly. This paper presents a case study where excessive pavement pressure damaged a two-span conventional bridge spanning Interstate 35 in Moore, Oklahoma. The bridge was instrumented with vibrating wire sensors to gather information on the behavior of the bridge before and after the repairs. There is a dearth of sensor verified observations of excessive pavement pressure acting on conventional bridges. The sensor data provided in-depth information on the response of the distressed bridge before and after repairs to thermal loading. Prior to the repairs the approach pavement was pushing on the bridge deck and causing the abutment backwalls to tilt toward the bridge. Following the repairs, the approach pavement is no longer pushing on the bridge deck. However, the abutment backwall is now moving in response to thermal changes in the bridge deck, likely due to excessive friction between the deck and the abutment backwall. U-shaped shaped cracking and spalling, previously observed in integral abutment bridges, was observed at this conventional abutment bridge, and the mechanisms causing these cracks and spalling are discussed. Through this study it was found that placement of pavement pressure relief joints relative to the bridge is crucial for reducing the magnitude of stress acting on the bridge. It was also found that the pavement stress acting on a bridge deck can be estimated with vibrating wire strain gauges given a baseline strain response for the approach pavement. [ABSTRACT FROM AUTHOR]

Various applications of incinerator bottom ashes (IBA) have been considered sustainable in many countries for years. This study evaluated the suitability of applying IBA added pervious concrete as roadway base course. Material properties, mix proportion, and an in situ test section were evaluated. The IBA were found to have good mechanical properties compared with natural aggregates. The results of the mix design indicated that increasing IBA will lead to a reduction of compaction strength. It was found that mixtures with less than 60% IBA replacement can give acceptable performance that meets specifications. Adding IBA to pervious concrete does not reduce its volumetric stability. In situ test results indicated that the permeability and noise of test sections with IBA are better than those of traditional asphalt concrete pavement. Roughness and rutting of test sections with IBA are similar to, although slightly worse than, those of traditional asphalt concrete pavement. Water samples showed that IBA-containing pervious concrete had only slight Cu leaching, which was much lower than the limits permitted by standards. It was concluded from all the test results and observations in this study that applying IBA-containing pervious concrete as roadway base course is adequate under the given conditions. [ABSTRACT FROM AUTHOR]

Due to the constraints of structural bearing, guardrail elevation, and milling depth of cement-paved bridge deck, the white-to-black maintenance of concrete bridge deck always has been a technical problem in road maintenance. This paper proposes a technical solution to the maintenance of concrete bridge deck by using a hot-mixed ultrathin wearing course. The road performance and construction technology were studied. The results of indoor performance tests show that the residual stability of Marshall immersion tests and the ratio of freeze–thaw splitting strength were greater than 90, and the rutting dynamic stability was 4,786 times/mm , with better water stability and high-temperature performance. The results of engineering application show that the effect of application of hot mixed ultrathin wearing course in the white-to-black maintenance project of the concrete bridge deck is meaningful, and the test results of the performance indexes such as the skid resistance, flatness, and water seepage of the pavement are excellent. However, it is necessary to create drainage channels on the bridge deck. [ABSTRACT FROM AUTHOR]

To reduce the reflection cracking and interlayer bonding degree of cement concrete pavement, an isolation layer was set up between the water-stabilized base layer and the cement surface layer. Finite-element analysis was used to analyze the mechanical properties of the cement concrete pavement structure and the wax isolation layer. By changing the cohesive strength and internal friction angle of interlaminar structures, the effects of different friction coefficients on the pavement deflection, the maximum tensile stress of surface course, the maximum interlaminar shear stress, and the maximum tensile stress of base course were analyzed. Results showed that when the internal friction angle was 0°, the maximum tensile stress of surface course of cement concrete in the upper warpage state was 4.6 times of that in the lower warpage state; the change of internal friction angle had more influence on the concrete stress than did the change of cohesive force; and the internal friction angle needs to be controlled at 30° to 50° when the cohesion is less than 0.01 MPa. The mechanical property parameters of cement concrete pavement were obtained, which could provide a scientific basis for the pavement structure design with wax isolation layer. [ABSTRACT FROM AUTHOR]

Penetrating sealers have been applied to some concrete pavement joints to reduce moisture movement and provide additional durability in Wisconsin since 1999. In these projects, contractors were asked to first pressure-wash all saw slurry from sawed joints and allow them to dry thoroughly, then apply a silane sealer directly to the interior of the sawed joint. The objective of this study was to evaluate the effectiveness of penetrating sealer in protecting pavement joints through field investigation of three projects in Wisconsin. Site visit surveys along with sample evaluation of field cores were completed. Although there was no visual detection of the presence of sealers in in-service pavements, laboratory tests proved the presence and functionality through contact angle, absorption, and penetration depth. The depth of penetration ranged from 1.46 to 11.75 mm, with an average of 5.14 mm. Penetration was correlated with concrete strength where less penetration was associated with high-performance concrete. When compared with the samples without sealer, more than half of the joints with sealer were still performing better in terms of contact angle and absorption after 8.2 years of service. [ABSTRACT FROM AUTHOR]

The goal of this research is to evaluate whether it is possible and effective to detect honeycombing of concrete pavement using a ground-penetrating radar (GPR) during construction. The motivation is that identifying honeycombing of concrete during construction would help avoid the spread of consolidation problems in large pavement sections, which are costly and time consuming to repair. GPR has been used as a tool for concrete quality control and detection of delamination in reinforced concrete elements since the 1980s, but it has not been used for the early detection of relatively small air voids. In this project, first, preliminary field testing was conducted to determine the possibility of detecting honeycombs in existing concrete pavement. Then, air voids of different sizes, shapes, and depths were artificially created using spray-foam in several laboratory specimens and detected using a high-frequency GPR antenna at different times after concrete placement. Cores were extracted to validate GPR readings and determine the capability of this technique. Another field testing was conducted to evaluate the efficiency and economy of using GPR as a nondestructive quality control tool. Field and lab test results indicated that GPR could be efficiently used to detect air voids as small as 32 mm (1.25 in.) and as deep as 102 mm (4 in.) from the surface of the concrete pavement as early as the initial set of concrete. These findings suggest that GPR is an effective, efficient, and economic quality control tool for this application. [ABSTRACT FROM AUTHOR]

Signs of premature deterioration are customarily observed in areas adjacent to joints in concrete pavements. These areas, especially in cold regions, continue to hold water/solution (due to application of deicing salts) long after wetting events. This solution can contribute to the deterioration process by physical or chemical mechanisms. Until now, the root causes of joint deterioration are not fully understood because a multitude of reactions and mechanisms may be responsible for this deterioration. The goal of this study is to use forensic evaluation to classify the source of this damage and identify aspects contributing to joint deterioration of regional roads (chloride-based salts are directly applied) and residential streets (salts are borne by vehicle tires) inWinnipeg, Manitoba, Canada. In addition to visual inspection, this study characterizes the quality of air-void parameters and bulk properties (e.g., absorption, penetrability) of cores collected from both regional roads and residential streets. Also, the alteration of microstructure in concrete was assessed by thermal, mineralogical, and microscopy studies. The results revealed that the cores collected from regional roads had high intensity of microcracks and most air voids (both small and large) were filled with various levels of secondary depositions compared with the cores collected from residential streets. The deterioration of concrete is explained by a combination of physical and chemical aspects, due to the interaction of salts, freezing/thawing cycles, and wetting/drying with the hydrated paste. [ABSTRACT FROM AUTHOR]

Box structures have been commonly used under highways. They are installed at grade or at great depths. When a box culvert is buried at a shallow depth, vertical pressure and dynamic impact due to traffic loading transferred onto the roof of the culvert can induce deflections of the culvert. The effect of the traffic load on the response of the culvert depends not only on the magnitude, pattern, and speed of the traffic load but also on the pavement structure. To investigate these factors, a reinforced concrete box culvert under three roadway sections (concrete pavement, concrete shoulder, and unsurfaced fill) was tested under static and traffic loads. The total thickness of pavement layers was 0.65 m within the pavement section and decreased gradually towards the end of the culvert through the shoulder and the unsurfaced section. The culvert was instrumented with displacement transducers under the roof and pressure cells on top of the roof within the unsurfaced fill. A low-boy truck with a known axle configuration and load was used to apply seven static load combinations and traffic loads at different speeds. Deflections under the roof and pressures on the roof were measured. The test results show that the magnitudes of the deflections of the culvert roof under static loads were generally increased from the concrete pavement, the concrete shoulder, to the unsurfaced fill. The truck at a higher speed generally induced more deflections than that at a lower speed or stationary. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper documents the analyses of the underlying causes for longitudinal cracks (LCs) on newly rehabilitated jointed concrete pavement (JCP) on the basis of the field investigations on two projects of rehabbed JCPs in Guangdong, China, as well as a series of tests. Investigation of Qinglian Highway focused on performance of four strategies used to rehabilitate the old Qinglian Road, while performance of three types of separation layer (SL) applied in the rehabbed JCP was the focus of investigation on Jiaoling Project. Furthermore, several other common factors were investigated in both projects, including materials and construction quality during rehabilitation, overloaded truck traffic volume on rehabbed pavements, etc. The findings of the investigations indicated that subgrade replacement caused more LCs on the newly rehabbed JCP than rubblization and break-and-seat which had been used to rehab old QingLian Road because it seemed to have caused plastic deformation and nonuniform compaction of the replaced subgrade attributable to diversity of replacing materials, variances in moisture content of replacing materials, and some problems related to construction. The plastic deformation and nonuniform compaction, in turn, led to uneven settlement of the replaced subgrade and then voids underneath new surface slabs. Voids combined with overloaded truck traffic were attributed to most of LCs on Qinglian Highway. While in Jiaoling Project, SL of 3 cm soft asphalt concrete (AC) with penetration numbers 200-300 performed better in stopping cracking than SL of geotextile and no SL if the original slabs and subgrade were stable because AC could generate higher strain under loading, more efficiently reducing the modulus of elasticity at the interface between base and surface slab and counteracting stresses SL of AC effectively broke the bond between base and surface slab so as to decrease early age cracks. Meanwhile, in both projects, over 80% of cracks were observed on the southbound lanes in which over 80% of overloaded trucks were running, although both directions of each pavement section had been rehabbed with the same structure and same materials. Thus, heavy truck traffic has been one of the major factors causing distresses of highways in China. [ABSTRACT FROM AUTHOR]

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; (3) SH12; (4) SH342; and (5) IH35W. Based on the available test results from these five projects, it was observed that the W1-W3 threshold values of 5.5 mils (0.140 mm) for exposed concrete pavement and 6.5 mils (0.165 mm) for composite pavement with existing hot mix asphalt overlay and an OT threshold value of 700 cycles correlated well with the field performance. Ignoring either of these critical factors may lead to premature reflective cracking. [ABSTRACT FROM AUTHOR]

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 (<40%) at longitudinal construction joints. Pumping and settlement problems were more pronounced where the tie bars failed; the resulting large deflections exacerbated the pumping and settlement problems. The results demonstrate the importance of adequate LTEs (>80%) provided by tie bars, base and subgrade support, in providing satisfactory JCP performance. Inadequate design or construction of any of these critical elements could lead to performance problems, potentially including severe settlement, which is quite difficult to repair. To repair this pavement section, the Paris District of TxDOT is planning to retrofit tie bars by the “slot stitching” method, along with filling the voids under the slab using grout, followed by thin overlay using latex modified concrete to correct the differential elevation problems at longitudinal construction joints. It is expected that this repair strategy will address the distress problems and extend the pavement life. [ABSTRACT FROM AUTHOR]

Bond-breaker media have been used with success to reduce and minimize undesirable cracks reflecting from cement-treated or lean-concrete subbases (LCSs). The common bond-breaking media include (1) emulsion slurry seal; (2) 30 to 60-mm-thin asphalt concrete; (3) one or two applications of wax-based curing compounds; (4) one or two layers of polyethylene sheets; and (5) geotextile. The cost differences among different bond-breaking media are significant for a highway project over 200 km long. Different types of tests (British pendulum friction, push off, pullout, and torsion) were performed to determine the cost-effectiveness of bond-breaking media. It was found that the bond stress had been reduced by approximately 90% when either emulsion wax curing compound (EWCC) or emulsion slurry seal was used. The results from the British pendulum, push-off, pullout, torsion, and cost analyses indicate that EWCC is the most cost-effective bond-breaker medium. Based on the observations from the laboratory testing and field trial section, the EWCC application rate was selected at 0.4 L/m2. As evident from the push-off and torsion test results, the effectiveness of the EWCC as a bond-breaker medium decreased with time. Thus, a second application of EWCC is required if the LCS base has been exposed to the environment for more than 14 days. The 216-km project was successfully constructed with EWCC. It resulted in a more than $7 million savings by using EWCC instead of emulsion slurry seal. No distress or cracking has been observed after the section was opened to traffic for more than 1 year. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper first describes the current state of analysis for the response of unreinforced concrete masonry walls subjected to lateral uniform pressure. The formulation is based on the initial elastic response, the subsequent initiation of cracks and the nonlinear rocking response, and the eventual large displacement and potential collapse. The necessary equations are developed for these phases in the form of a resistance function. The paper then incorporates membrane retrofit materials to strengthen the wall’s resistance to lateral pressure, and develops the necessary resistance function equations. In blast tests, membrane retrofit unreinforced masonry walls have experienced severe cracking and large displacements without collapse. This is of high interest to the Department of Defense, the protection of diplomatic facilities, and the construction industry impacted by hurricanes and other high wind events. The paper concludes with examples that demonstrate application of membrane retrofits indeed increase the resistance of the wall to lateral pressure. [ABSTRACT FROM AUTHOR]

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 support. This is significant in that there are no effective and practical methods to improve subbase conditions in existing concrete pavement, whereas DBR can restore pavement conditions at a reasonable cost. However, not all DBR projects were successful. In one DBR project, faulting in the range of 6.4–9.5 mm occurred after less than 2 years of treatment. Forensic investigation revealed voids under the dowel bars, which indicates poor consolidation of the grout material. Efforts are currently underway in TxDOT to improve specifications for grout materials and DBR construction. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

Past studies have shown that initial pavement roughness greatly affects future pavement roughness and roughness progression rate. Initial pavement roughness is also an important input to the roughness prediction model in mechanistic-empirical design guide. This study analyzed the design and construction factors affecting initial pavement roughness. Initial international roughness index of 90 concrete pavements constructed in Wisconsin from 2000 to 2004 were analyzed using multiple regression method. The factors considered in this study included concrete pavement slab thickness, project location, dowel bar placement, joint spacing, base type, and pavement length. The factors affecting initial pavement roughness were identified. [ABSTRACT FROM AUTHOR]

Lack of proper pavement base and subgrade compaction leads to premature failures that account for millions of dollars in damages. Controlled low-strength material (CLSM) concrete was introduced in this study as pavement base material near a manhole where proper compaction is unachievable. Rut-resistant stone matrix asphalt was placed on top of the CLSM as a wearing surface layer. Dynamic cone penetrometer (DCP) testing was used to monitor CLSM construction. One day after placing, the CLSM gained sufficient strength to support construction traffic. Further, DCP results indicated that the CLSM possessed uniform characteristics of concrete that could improve the load-bearing capacity and serviceability of the pavement near the manhole. After 18 months of heavy truck traffic, maximum rutting was 5 mm, well below the failure criteria of 12.5 mm. Based on cost and performance, CLSM concrete has the potential to improve problematic areas in pavement. [ABSTRACT FROM AUTHOR]

Plain jointed concrete pavements laid in Mumbai City (India) during the early 1990s were structurally evaluated using a falling weight deflectometer (FWD) and testing of concrete cores extracted from the pavement slabs. The ultrasonic pulse velocity (UPV) of the concrete in the cores was determined first and then the cores were crushed under compression. The pavement deflections were found to be within the limits as suggested in the Indian codes and the international literature. The joint conditions were also found to be satisfactory. The design strength of the concrete was back-calculated from the compressive strength of the cores and was found to conform to the design specifications. However, the construction quality was found wanting as the thickness of pavement slabs at a few locations was lower than that specified and it has resulted in cracking of the slabs. The dynamic modulus of elasticity of concrete as determined by the FWD was found to correspond well with that computed from the UPV of cores and from the compressive strength of concrete. A method is suggested to estimate the structural parameters of uncracked pavement slabs from the dynamic modulus of elasticity obtained through the indirect method of UPV testing which is less expensive compared to evaluation by the FWD. [ABSTRACT FROM AUTHOR]

Heaving of pavements and a building foundation became progressively worse on a project at Holloman Air Force Base (AFB), N.M. The cause of the heaving was identified as sulfate attack on recycled concrete used as fill and base course below the buildings and pavements. This recycled concrete came from sulfate-resistant airfield Portland concrete pavement that had existed for decades at Holloman AFB without distress. However, severe sulfate exposure conditions, ready availability of water, the more permeable nature of the crushed recycled concrete, less common thaumasite attack, possible soil contamination as a secondary source of alumina, or some combination of these factors allowed sulfate attack to develop in the recycled material even though it had not in the original concrete pavement. [ABSTRACT FROM AUTHOR]

The Illinois Department of Transportation (IDOT) initiated a failure investigation to determine the distress mechanisms causing premature longitudinal cracking on continuously reinforced concrete pavements (CRCP) on several Illinois interstates. The longitudinal cracking approximately followed the embedded reinforcement steel and occurred in both the driving and passing lanes. In this paper, the results from field visual surveys, coring, and petrographic analyses are reported along with a review of archival construction and material records of the distressed CRCP sections. A laboratory forensic study was also performed on several field extracted slabs. The results of the field and laboratory investigation show the cracking was not initiated by steel corrosion, deleterious reactions in the concrete materials, or an inadequate structural design. Rather, the cracking is related to settlement of the steel bars in the concrete. Settlement cracking is conventionally thought to occur only in concrete slabs and decks with plastic (high slump) concrete and small values of bar cover depth, while the studied CRCP sections have large values of cover depth and were cast with stiff (low slump) concrete. The settlement was likely caused by the relative settlement of heavy steel bars (22 mm diameter) within the lower density concrete during the original CRCP construction. The technique of placing the steel bars in the fresh concrete (called tube-feeding) further contributed to the development of this distress, and this practice is no longer employed by IDOT. [ABSTRACT FROM AUTHOR]

The main objective of this study is to identify the cause of the punchouts observed on Interstate Highway 30 (IH-30), and to identify possible rehabilitation alternatives. Several nondestructive tests, as well as coring and trenching, were conducted in both distressed and nondistressed areas. Middepth horizontal cracks were found during routine repair and by the trenching performed in this study. It is believed that due to temperature variation at an early stage, horizontal cracks developed at the middepth interface between the steel and concrete. The truck traffic caused the horizontal cracks to deteriorate further. Repetitive truck traffic and thermal loading forced the concrete to crack vertically from the middepth where there were horizontal cracks. The closely spaced transverse and longitudinal cracks, along with the delamination, caused punchouts. Although the problem is not imminent, an immediate seal plus a 75 mm heavy-duty stone matrix asphalt (SMA) overlay will probably provide the most cost-effective remedy for this section of IH-30. Existing distressed areas should be repaired before the rehabilitation. To slow the deterioration, the district should use a latex modified chip seal or asphalt rubber seal (AC15-5TR) followed by a 75 mm heavy duty SMA. This is to provide bonding between the concrete and SMA overlay. If the district chooses to do nothing at this time, it will become costly in 2–3 years if current environmental and traffic conditions hold. The cost to repair a severely deteriorated continuously reinforced concrete pavement (CRCP) would be several times more than the 75 mm heavy duty SMA overlay. [ABSTRACT FROM AUTHOR]

A parametric study was conducted using the finite-element rigid pavement program ISLAB2000. For cracks that utilize aggregate interlock as the sole means of load transfer, the integrity of the cracks was initially modeled using the aggregate interlock factor. A subsequent analysis was then performed on the same cracks for the case where both dowel bars and aggregate interlock were available for load transfer purposes. The latter scenario represents the case where dowel bar retrofitting (DBR) has been performed on the cracks. In both cases, the deflection load transfer efficiency and critical slab tensile stresses were computed in order to examine the immediate theoretical benefits of the dowel bars. The validity of these theoretical benefits was tested using data from falling-weight deflectometer testing on DBR sites in both Michigan and Washington. It was found that installation of dowel bars did not increase the load transfer efficiency for cracks that had levels greater than 89–95%, depending on pavement parameters. When temperature gradients were not considered, little change in tensile stress due to a load at the crack was exhibited when DBR was performed on cracks that had load transfer efficiency levels less than 70–80%. [ABSTRACT FROM AUTHOR]

Environmental effects and repetitive traffic applications can lead to the development of transverse cracks in jointed concrete pavements. Maintaining adequate aggregate interlock load transfer across these cracks is essential to preserving the functional and structural integrity of these pavements. The objectives of this study were to determine the design parameters that significantly affect transverse cracking and to demonstrate methods available for evaluating cracked pavements. Field data collected from in-service jointed concrete pavements located throughout southern Michigan were used to accomplish these objectives. Joint spacing, coarse aggregate type, shoulder type, and pavement temperature were found to have significant effects on transverse crack development and/or performance. The surface texture of crack faces was assessed using a promising new test method called volumetric surface texture testing. Volumetric surface texture results provided an indication of the aggregate interlock potential of pavements containing various aggregate types. Three performance parameters capable of mechanistically characterizing crack performance were discussed. A relatively simple procedure was described for determining these parameters and evaluating crack conditions. Field data were also used to demonstrate and validate a voids' analysis procedure. This procedure estimates the potential for loss of support near cracks and joints, thus allowing for proper rehabilitation actions to be taken prior to the manifestation of additional distresses. [ABSTRACT FROM AUTHOR]

Structures underneath pavements commonly reduce the bearing capacity of the ground because of poor compaction and long-term settlement at sites around these structures. When a load is applied at these sites, the stress on the concrete slab increases and may exceed the design strength, inducing distress and shortening the lifespan of the pavement. In this study, we investigated the transverse cracking of concrete pavement slabs above box culverts in a test road of the Korea Expressway Corporation. Transverse cracking in the slabs was surveyed in both the north- and southbound lanes with different cover depths over the box culverts. To examine the transverse cracking, the jointed concrete pavement of the test road containing the culvert was modeled and analyzed by the finite-element method. Wheel loading was applied after taking into account the self-weight of the pavement and the temperature gradient within the concrete slab. The positions and magnitudes of the maximum tensile stress and the corresponding positions of wheel loading were investigated for each loading combination. In this manner, we identified the optimal joint positions for which the maximum tensile stress in the pavement slab is minimized. We also analyzed the behavior of the pavement in relation to the cover depth and reinforced concrete transition slab length. Accordingly, we proposed an appropriate length for the reinforced concrete transition slab to ensure minimized tensile stress in the pavement slab. [ABSTRACT FROM AUTHOR]

This study focuses on determining the effect of different types of binder and aggregate on chip seal performance in both laboratory and in situ settings. Eight different chip seal test sections were constructed on existing asphalt concrete as the pavement preservation technique of choice. Two different binders, CRS-2L modified emulsion and B100/150 penetration hot asphalt cement, were used in the test sections. Also, two types of aggregate, limestone, and basalt, were used. The sand-patch test as well as visual evaluations was conducted on the test sections regularly. In addition to physical and chemical characteristics, the adhesion resistance of the utilized materials was determined in the laboratory and compared with the test section results. The loss of aggregate (also called raveling or shelling), bleeding deteriorations on each test section were evaluated over time in respect to binder and aggregate type. The results indicate that after chip seal construction, the macrotexture of the existing asphalt concrete increased significantly. It was also determined that CRS-2L chip seal showed better performance than B100/150 penetration hot asphalt cement. With regard to the type of aggregate used for the chip seal, limestone showed better raveling performance when compared with basalt. In addition, in the test sections, the right and left lanes demonstrated different levels of severity distress because of varying traffic distributions. It was also seen that macrotexture is one of the best parameters to determine chip seal performance and to follow its progress over time. [ABSTRACT FROM AUTHOR]

Diamond grinding (DG) has been used 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 Texas Department of Transportation 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 (), 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 eight 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 to 18. Similarly, there was an average IRI reduction of approximately () immediately after the DG, or about 40%. Depending on the existing pavement conditions, the range of IRI reduction varies from (), 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 (). [ABSTRACT FROM AUTHOR]