Jointed Concrete Pavement Research Articles

Developing a Network-Level Structural Capacity Index for Composite Pavements

AbstractThe structural capacity of a pavement has been shown to be an excellent indicator of the required maintenance and expected performance of asphalt pavements, but studies reported in the literature have produced few indices for composite pavement systems. This paper presents a relationship to predict the future functional performance (i.e., the behavior of the surface condition over time) of composite pavements as a function of its structural condition measured using the falling weight deflectometer (FWD). Network-level deflection data were collected using the FWD between the years 2005 and 2007 on approximately 3,700 directional km (2,300 directional miles) of interstate pavements in Virginia. The network of pavements included asphalt, jointed concrete, and composite (asphalt surface over jointed concrete) pavements. The FWD data were then compared with the performance of several pavement segments that received maintenance treatment just before deflection testing. It was found that the measurements...

Uncracked joints in plain concrete pavements: causes, effects and possibilities of improvements

During the construction of Jointed Plain Concrete Pavements (JPCPs) in Chile, it was observed that joints remained uncracked. The objectives of this paper are to evaluate the effects of uncracked joints (UnCrJ) in JPCPs and to propose possible solutions or improvements to avoid or minimize this phenomenon. Considering low thermal amplitude as cause of UnCrJ, a rational-based, detailed and empirically validated model is used to predict UnCrJ and crack width. The modelled results are not only due to material changes but also to the location of the series of cracks in time in the JPCP system. The paper contributes with this rational approach, instead of an empirical-simplified one, to achieve the objectives. For the modelled conditions, the “as-built” slab length range is 8 m to 56 m instead of the 4 m designed one. Then, more curling, joint faulting, water infiltration in sealed joints and load transfer efficiency ≤ 70% are expected. The alternative solutions proposed are associated to innovations as short joints spacing, unsealed joints and saw-cuts up to 50% thickness made with thin blade (≤ 3mm), which was verified with new field evidence provided in the article.

Using neutron radiography to assess water absorption in air entrained mortar

Concrete highway and airport pavements are designed to be long lasting; however, some concrete pavements have shown premature deterioration at the cracks and joints. It has been hypothesized that one cause of this deterioration is associated with fluid ingress, especially in cases where those fluids contain deicing salts. This paper examines fluid ingress in mortar using a cross-sectional geometry that is similar to a typical concrete pavement joint. Time-dependent and spatial aspects of fluid ingress are examined using neutron radiography (NR), which was performed using the thermal neutron radiography station at the neutron spallation source at the Paul Scherrer Institut (PSI). Specifically, this paper examines the role of the initial relative humidity (or degree of saturation) and air content on the fluid ingress. The work indicates that the initial fluid ingress reaches a specific degree of saturation relatively rapidly, where the large capillary and gel pores appear to be filled in (commonly referred to as the nick point in sorption tests) and the entrapped and entrained air pores fill in more slowly over time.

Modeling of Dowel Jointed Rigid Airfield Pavement under Thermal Gradients and Dynamic Loads

Concrete pavements have been widely used for constructing runways, taxiways, and apron areas at airports. The aviation industry has responded to increased demand for air travel by developing longer, wider, and heavier aircraft with increasing numbers of wheels to support the aircraft while in ground operation. Many researchers developed their models based on the finite element method (FEM) for the analysis of jointed concrete pavement. Despite the notable improvement, important considerations were overlooked. These simplifications may affect the results of the developed models and make them unrealistic. Sensitivity studies were conducted in this study to investigate the effect of the loading parameters on the load transfer efficiency (LTE) indictors where concept of LTE is fundamental in airfield design procedures. The effect of main gear loading magnitudes in different wheel configurations combined with positive and negative thermal gradients was investigated. The verification process was presented to increases the confidence in the model results. Understanding the response of rigid airfield pavement under such circumstances is important developing a new pavement design procedure, as well as implementing a suitable remedial measure for existing pavements. The results obtained that utilizing a dynamic load allows studying the fatigue cycles that pavement can be subjected under different wheel configurations. Moreover, the change in the thermal gradient from positive to negative significantly changed the slab curvature shape.

Estimation of Joint and Interface Parameters for the Finite Element Analysis of Jointed Concrete Pavement Using Structural Evaluation Results

Abstract In the analysis of jointed concrete pavement, it is necessary to appropriately model certain aspects of the pavement for accurate estimation of its structural responses. These include load transfer at joints (doweled and aggregate interlocked) and interface condition between slab and foundation. This paper presents a backcalculation method for estimating the joint parameters, both transverse and longitudinal, and the interface parameter along with the pavement layer moduli by using the results of structural evaluation of an in-service concrete pavement. The details of the structural evaluation using Falling Weight Deflectometer (FWD) and the two-stage backcalculation procedure using a three-dimensional finite element (FE) model for jointed concrete pavement are discussed. Modulus of dowel support and modulus of interlocking joints are the transverse and longitudinal joint parameters respectively and the coefficient of friction between concrete slab and foundation is the interface parameter considered for the analysis. These parameters are the useful inputs in modeling jointed concrete pavement using finite element method.

Investigation of Approaches for Improving Interfacial Transition Zone-Related Freezing-and-Thawing Resistance in Concrete Pavements

Sawn joints in concrete pavements appear to be more susceptible to deterioration under cyclic freezing and thawing than formed joints. One mechanism appears to be related to water and salt solutions more readily penetrating into the concrete through the exposed interfacial transition zone (ITZ) at the saw-cut joint. This in turn will increase the risk of local expansion or dissolution around the aggregate particles at the joint face. The work described in this paper was conducted to evaluate this hypothesis. A range of concrete mixtures with different water-cementitious materials ratios (w/cm) and silica fume contents were tested in a range of deicing solutions and subjected to cyclic freezing and thawing. The data indicate that improving the quality of the ITZ does help to reduce the risk of damage. In addition, the results revealed that saturated concretes have lower freezing-and-thawing resistance compared to concrete simply soaked for a short time.

Computational Approach to Investigation of Crack Behaviour under Vehicular Loading of A Typical Concrete Pavement (A Case Study of Mbagathi Road in Nairobi)

Nairobi County has nearly 100% road network as bituminous roads and only 4km road network (Mbagathi Road) is concrete road. This road was a pilot project that was implemented by Kenyan Government between the years 2005 and 2007 at a total construction cost of over 400 million Kenya Shillings. The design was done based on South Africa design procedure on a 210 mm thick PJCP pavement. Performance of Plain Jointed Concrete Pavement (PJCP) depends on aggregate interlock, which is the mechanism by which loads are transferred from one slab to the adjacent one. This study attempted to use the information on load transfer mechanics in order to quantify the effect of aggregate properties to crack size as well as the propagation of any cracks formed in service. This research was undertaken in two different ways namely experimental and computer simulation. The experimental approach entailed measuring widths and depths of cracks existing in Mbagathi road, and also involved setting up concrete beams in the laboratory and loading them to failure with predetermined loads and measuring sizes of resulting cracks. On the other hand, the computational approach was verified by experimental results entailed simulating crack widths and depths with recent devised fracture models. Cracks were experimentally noticed to occur due to loading the pavement with vehicular loads bigger than safe load. Cracks generated had crack width equivalent to the measured flexural deflection and for an ideal concrete pavement crack width and crack depth exhibited an exponential relationship. It was found that vehicular loads induce stresses in concrete pavements which exceed permissible tensile stresses, hence a better understanding of the resultant cracks, as well as their propagation. This research will lead to an improvement of the design of concrete pavements in Kenyan environment.

Numerical Investigation of the Shape Memory Alloy Dowels in Jointed Concrete Pavements

Shape memory alloy (SMA) is a novel functional material, which has found increasing applications in different engineering aspects. This research presents a finite element analysis of the potential benefits of SMA dowel bars on the jointed concrete pavements (JCP). With a 3-dimonsional (3D) Finite element modelling (FEM) and application of the damaged plasticity model, the tensile damage around the three types of SMA dowels are calculated, and the results are compared to conventional steel dowel bars in the JCP. It was found that SMA dowels considerably reduce the damages around the dowels through the concrete slabs. The load transfer efficiency (LTE) of the pavement equipped with these smart dowels are also have been discussed. To gain further understanding of the pavement behavior, a dynamic load was repeated a thousand times on the model. The damage and the LTE under repetitive loads have been investigated, and it is concluded that SMA dowels can maintain their load efficiency even under highly repeated loads, while causing less tensile damages to the pavement.

Field performance with state-of-the-art patching repair material

Significant efforts have been made to identify the correlations between pavement design, materials and construction variables and pavement performance for new pavement construction; in response to these efforts, specifications and design standards have been developed to optimize pavement performance. On the other hand, less positive correlations have been found between pavement repair materials/methods and the performance of repairs. This issue is primarily due to the incompatibility between existing pavement and repair materials including bonding at the repair interface, as well as the complex nature of pavement behavior near distressed areas. As a result, the variability in the performance of pavement repairs has been rather large. As more pavement sections have reached or even exceeded their design lives, with more frequent distresses, it is important to identify optimum repair methods and/or materials. This paper presents the field performance of several repair strategies with Fiber Reinforced Polymer Patching Binder (FRPPB) patching material for the repairs of spalling, partial-depth punchout and longitudinal joint separations in rigid pavement, for retarding reflection cracking in asphalt overlay on jointed concrete pavement, and for repairs at the transition area between rigid and flexible pavements by the Texas Department of Transportation (TxDOT). The repairs for these distress types have been a challenge to TxDOT districts; repair specifications with acceptable properties of repair materials and methods have not been as well-developed as the specifications for new construction have, resulting in a large variability in the performance of repairs of these distresses.The performance of repairs for the distresses mentioned above with FRPPB has been excellent, with no need for repeated repairs up to this point. The results from this study indicate that if the right materials are used for repairs, along with the correct repair method, the performance of pavement repairs and rehabilitations could be substantially enhanced, minimizing traffic delays and financial resources associated with further repairs and rehabilitations.

Effects of Hinged Dowel System on the Performance of Concrete Pavement Joints

Concrete joint failure is a major distress mode in rigid pavements. Improving the joint performance in concrete pavements could yield substantial savings in terms of reduced maintenance and rehabilitation costs. The newly developed Hinged Dowel System (HDS) is a means for transferring loads across the concrete pavement joints. The HDS was patented as a new invention by the United States Patent and Trademark Office, and it is envisioned that it could significantly reduce the potential for joint failure in concrete pavements. The HDS assembly comprises a number of dowel bars and a collective hinge provided at the mid-length of the dowel bars. A finite element analysis showed that the application of HDS reduces the shear stress in concrete pavement joints by approximately 15% when compared to the conventional dowel bars. This amount of reduction in shear stress could translate into a significant reduction in shear-induced failures in concrete pavements. The HDS includes mechanisms which would allow a horizontal slip condition for the dowel bars imbedded in concrete. Moreover, these mechanisms eliminate the punching stress at the dowel tip, which is often induced by thermal expansion of the concrete slabs. The hinge in the HDS gives the concrete slab joints a degree of flexibility to reduce the stresses caused by daily curling and warping of slabs, and seasonal expansion and contraction. In addition to installation in new concrete pavements, the HDS could be utilized in retrofit of old concrete pavements. Finally, the HDS eliminates most construction-related issues associated with the installation of dowel bars, such as dowel bar misalignment and full-depth joint cut.

Impact of different approaches to modelling rigid pavement base layers on slab curling stresses

The magnitude of stresses induced in jointed concrete slabs due to thermal loads is influenced by the stiffness of the underlying foundation layers (base, sub-base and subgrade). The layer that most significantly affects the Portland cement concrete (PCC) slab responses is the base. Field observations have demonstrated the increase in reflecting cracking of PCC slabs placed over relatively stiff base layers. To predict thermo-mechanical responses of jointed PCC slabs accurately, appropriate idealisation of foundation layers in finite element (FE) analysis is required. Several modelling methods have been proposed to idealise the effect of the base layer. These methods differ in the structural contribution assigned to the base layer in the pavement concrete system. Four approaches for modelling the base layer in FE analysis of jointed concrete pavements are presented in this paper. The first and second approaches involve modelling the base as a plate separate from the other foundation layer(s). In the third and fourth approaches, the base layer is modelled as part of a Winkler or Vlasov foundation, respectively. A series of parametric studies are carried out to evaluate the capability and feasibility of each modelling approach proposed in this study in reflecting the effect of the base course rigidity on the PCC slab responses under thermal loads.

Testing of Dowel Alignment and Development of a Dowel Bar Alignment Specification for Illinois Tollways

Dowel bar alignment is a key requirement in highway agencies' construction specifications for jointed concrete pavement. This requirement, however, has not been rigorously enforced by most highway agencies because there has been no practical and quick means of measuring dowel alignment until recently. Since 2005, FHWA has encouraged nondestructive techniques to determine dowel alignment, principally through the use of the MIT Scan device. Separate from the measurement of dowel bar alignment is the issue of acceptable tolerances for dowel bar alignment; this involves consideration of the variability inherent in test procedures for dowel bar alignment. Many U.S. highway agencies are reevaluating decades-old tolerance limits for dowel bar alignment. This paper summarizes recent work performed for the Illinois State Toll Highway Authority to develop more rational specifications for dowel bar alignment for use on ongoing concrete pavement construction projects in the Chicago area. The specifications were developed after extensive field testing during 2013 to verify that Chicago area contractors were able to meet proposed tolerance levels in the new specification for dowel bar alignment.

Computational Approach to Investigation of Crack Behaviour under Vehicular Loading of A Typical Concrete Pavement (A Case Study of Mbagathi Road in Nairobi)

Nairobi County has nearly 100% road network as bituminous roads and only 4km road network (Mbagathi Road) is concrete road. This road was a pilot project that was implemented by Kenyan Government between the years 2005 and 2007 at a total construction cost of over 400 million Kenya Shillings. The design was done based on South Africa design procedure on a 210 mm thick PJCP pavement. Performance of Plain Jointed Concrete Pavement (PJCP) depends on aggregate interlock, which is the mechanism by which loads are transferred from one slab to the adjacent one. This study attempted to use the information on load transfer mechanics in order to quantify the effect of aggregate properties to crack size as well as the propagation of any cracks formed in service. This research was undertaken in two different ways namely experimental and computer simulation. The experimental approach entailed measuring widths and depths of cracks existing in Mbagathi road, and also involved setting up concrete beams in the laboratory and loading them to failure with predetermined loads and measuring sizes of resulting cracks. On the other hand, the computational approach was verified by experimental results entailed simulating crack widths and depths with recent devised fracture models. Cracks were experimentally noticed to occur due to loading the pavement with vehicular loads bigger than safe load. Cracks generated had crack width equivalent to the measured flexural deflection and for an ideal concrete pavement crack width and crack depth exhibited an exponential relationship. It was found that vehicular loads induce stresses in concrete pavements which exceed permissible tensile stresses, hence a better understanding of the resultant cracks, as well as their propagation. This research will lead to an improvement of the design of concrete pavements in Kenyan environment.

Concepts to Enhance Specification and Inspection of Curing Effectiveness in Concrete Pavement Design and Construction

This paper presents an approach that can be used to consider the effect of the quality of curing and the time of placement (collectively referred to as “curing effectiveness”) on the development of the set gradient and its importance to long-term performance of jointed concrete pavement structures. The approach involves the definition of a curing quality index, referred to as the “effectiveness index,” that is reconfigured to function as a boundary interface to account for the effect of ambient conditions and represent the method of curing on potential moisture evaporation during hardening shortly after construction. Moisture and temperature boundary conditions are incorporated into a simple spreadsheet tool to evaluate heat and moisture transfer mechanisms at the cured surface of a concrete pavement during placement operations. Key parameters for development of set gradients in a concrete slab are identified, and a discussion is presented about how these parameters can be included in construction specifications and monitored as part of routine inspections. This paper also explains a laboratory and field protocol to monitor curing quality and facilitate an inspection program for concrete pavement construction and satisfy specification requirements to meet an expected design life.

Field assessment of a jointed concrete pavement foundation treated with injected polyurethane expandable foam

This paper describes in situ measurement results and analysis of a deteriorating jointed concrete pavement supported on open-graded aggregate subbase that was subsequently treated with high-density polyurethane foam. The foam was injected under pressure into the subbase to improve support conditions, mitigate faulting and improve load transfer efficiency (LTE) at the joints. A variety of in situ tests were conducted to evaluate ride quality, pavement deflections under dynamic loading, LTE at joints and cracks, pavement surface elevation changes, and drainage and stiffness of the treated subbase layer. Testing on the pavement surface indicated statistically significant improvements near cracks after treatment with reduced peak deflections and higher LTE, but the pavement ride quality measurements did not show improvement. Tests performed on the foundation layer indicated that the construction process resulted in concentrated zones of foam in the subbase with low permeability, low stiffness and high shear strength, compared with untreated areas.

Effect of daily temperature variations on the continuous deflection profiles of airfield jointed concrete pavements

Compared with highway roads primarily damaged by repeated vehicle loads, airfield pavements suffer more from heavier aircraft loading, along with environmental factors. In particular, a pavement temperature is one of the critical factors affecting the behavior and response of airfield jointed concrete pavements (JCP). Temperature variations cause curling and expansion/contraction of a slab, which may ultimately influence the in-situ deflection measurements. Along with the pavement temperature, it is well known that other parameters such as subsurface conditions (i.e. stiffness of base/subbase layers), setting temperature of concrete, slab dimensions, and joint/crack width also affect the behavior and response of JCP. The main objectives of this paper are to characterize: (1) the behavior of airfield JCP due to temperature variations in terms of pavement “deflections” (defined as the dynamic movements of a pavement induced by dynamic loading); and (2) the effects of various affecting parameters on the vertical displacement profile of JCP slabs. The primary research means include in-situ pavement deflection measurements at different times of a day. For this purpose, a rolling dynamic deflectometer (RDD) which measures the continuous deflection profiles along a selected pavement section (100% coverage of a tested path) was employed. Also, extensive two-dimensional numerical simulations were performed to provide supporting evidence for the behavior trends generated by RDD.

Evaluating performance of concrete pavement joint repair using different materials to reduce reflective cracking in asphalt concrete overlay

Joint damages are commonly seen in old jointed concrete pavement (JCP). A joint restore should be conducted before rehabilitation by placing an asphalt concrete (AC) overlay in order to prevent the reflective cracking in the AC layer. This study was performed to experimentally investigate the rehabilitation strategy of a joint damaged JCP in terms of the performance of the repair materials and the effectiveness of the structure design through beam tests. Three types of repair materials were used and the beams were tested under the three-point bending. The repair materials used were plain concrete, engineering cementitious composite (ECC) and ECC-dowel combination. The flexural behaviour, fracture energy, crack pattern, and failure mode were investigated to evaluate the effectiveness of rehabilitation for future engineering application.

Unsupervised Artificial Neural Network for Efficient Mapping of Doweled Concrete Pavement Joints Condition

Concrete pavement joint evaluation involves a number of assessment criteria, such as deflection near the joint, load transfer efficiency of the dowels and severity of voids under the slab. Although there are well defined thresholds for each of these parameters, often there arises a situation where each of the considered parameters lends contradictory assessment that leads to a considerable subjectivity in the evaluation process. A Self-Organizing Map (SOM), an unsupervised learning procedure in artificial neural network, is utilised for the first time to map the joint condition of concrete pavements from Falling Weight Deflectometer (FWD) deflection bowls. A novel methodology is proposed for labelling the network, whereby pavement engineering expertise can be directly used in a SOM for consistent deflection data classification in joint evaluation. The effectiveness of the trained network is demonstrated by using joint assessment parameters; namely, load transfer efficiency (LTE), void intercepts and absolute deflection. The joints were classified as good, marginal or poor. For the three parameters based SOM classification, an accuracy of 65-70% was obtained; this improves to 87.5% when the SOM was trained with 2-parameters (LTE and absolute deflection). However, when the SOM was tested with the data classified as 'good', accuracy improves to around 90%. Therefore, a SOM can be a powerful supplementary tool for a consistent and non-subjective evaluation of concrete pavement joints.

Approach to identify misaligned dowel and tie bars in concrete pavements using ground penetrating radar

Dowels are used in jointed concrete pavements to provide load transfer and improve performance. Misaligned dowels could cause poor joint performance that would lead to pavement distresses. An approach to detect misaligned dowel bars in concrete pavements using GPR is proposed. The paper addresses all forms and combinations of dowel misalignment. Equations were developed to identify each misalignment type, and statistical analyses were performed on major categories for the entire project. A decision on the acceptance or rejection of a dowel bar, a joint, or a pavement section, can be made based on the results of the computations and specified tolerance values.

Bonded continuously reinforced concrete overlay on jointed concrete pavement

A cost-effective strategy is needed to remedy the decaying jointed concrete pavements (JCP). The distress problems continue to cause poor ride quality and continued expense and delay to the traveling public. To explore the bonded concrete overlay (BCO), a half mile section was constructed with a 178 mm continuously reinforced concrete (CRC) overlay. Two other nearby sections were monitored along with the CRC BCO section, over the following 3 years. Over the 3 year period, the CRC BCO section was far less expensive to maintain than the other sections that continued to receive conventional full-depth repair (FDR). The ride quality of the CRC BCO section is also improved by approximately 60–100 inches/mile over conventionally FDR sections. It is believed that the CRC BCO offers a cost advantage over the conventional FDR strategy, and should be considered for future JCP rehabilitation projects.