Continuously Reinforced Concrete Pavement Performance Research Articles

Evaluation of Design Procedure and Performance of Continuously Reinforced Concrete Pavement According to AASHTO Design Methods.

The Guide for Design of Pavement Structures (AASHTO 86/93) and Mechanistic Empirical Pavement Design Guide (MEPDG) are two common methods to design continuously reinforced concrete pavement (CRCP) published by the American Association of State Highway and Transportation Officials (AASHTO) in the USA. The AASHTO 86/93 is based on empirical equations to assess the performance of highway pavements under moving loads with known magnitude and frequency derived from experiments on AASHTO road tests. The MEPDG is a pavement design method based on engineering mechanics and numerical models for analysis. It functions by incorporating additional attributes such as environment, material properties, and vehicle axle load to predict pavement performance and degradation at the selected reliability level over the intended performance period. In order to evaluate the CRCP design procedure and performance, crack width (CW) and crack spacing (CS) from five examined test tracks in Europe with different climate condition, base layer, geometry, and materials were collected in this paper and compared with predicted distresses as well as CW and CS from AASHTO 86/93 and MEPDG design methods. The results show that the interactions between geometrics, material properties, traffic, and environmental conditions in the MEPDG method are more pronounced than in the AASHTO 86/93 and the prediction of CS and CW based on MEPDG matched closely with the recorded data from sections.

Assessment of California’s Continuously Reinforced Concrete Pavement Practice and Performance

Around 2009, the California Department of Transportation (Caltrans) adopted continuously reinforced concrete pavement (CRCP) as the preferred pavement type for high-volume truck corridors across the state. Over the last decade, Caltrans has constructed more than a dozen CRCP projects in different climates and exposure to different truck volumes. Caltrans was interested in assessing early CRCP performance and identifying potential areas where design, materials, plans, and specifications, and/or construction practices warranted improvement. This project included a review of national CRCP practice, documentation of Caltrans’ statewide practice, and condition assessment of select CRCP projects statewide. For the most part, Caltrans’ CRCP practice is similar to national guidance and other state highway agency practice. A condition assessment of 14 CRCP projects revealed a wide range of performance with various degrees of distresses (i.e., transverse, cluster, and Y-cracking, and punchouts). However, pavements with average transverse crack spacing below Caltrans’ desired lower limit of 3 ft appeared to have acceptable performance. Excessive map cracking, a high percentage of cluster cracking, and initial development of punchouts was evident in sections that appeared to be performing poorly. General recommendations are provided to advance Caltrans’ CRCP practice.

A method for evaluating CRCP performance based on edge-loaded FWD test

The backcalculated modulus of subgrade reaction (k-value), elastic modulus of concrete (E), and effective thickness (heff) given the deflection basin from the Falling Weight Deflectometer (FWD) testing has been extensively used in evaluating the response and performance of in situ concrete pavements. Traditional backcalculation assumption of an interior-loaded infinite slab can lead to large errors in backcalculated parameters for edge-loaded continuously reinforced concrete pavement (CRCP) because of the load position and closely-spaced transverse cracks. In this paper, the backcalculaion formulas for edge-loaded CRCP with various crack spacing was proposed based on 2-D finite element analysis. According to the backcalculated results, both positive and negative temperature differentials of less than 16 °F had limited impact. As expected, the larger the lateral offset of the plate, the greater the impact on backcalculated results given the minimum error in heff reaching 5.0% with a 4 in. lateral offset. In order to verify the proposed backcalculation method, a field CRCP test section with different base types and reinforcement ratio were evaluated. The impact of edge support provided by base layer was also shown to be significant, given the support of a 2 ft overwidth base showing the same impact of approximately 1 in. extra thick base.

Punchout evaluations and classification of continuously reinforced concrete pavement to improve pavement design

In continuously reinforced concrete pavement (CRCP) research, it has been assumed that transverse crack spacing plays an important role in determining CRCP behaviour and performance. For the longitudinal reinforcement design, the 1993 American Association of State Highway and Transportation Officials (AASHTO) Design Guide recommends a minimum crack spacing of 3.5 ft. The minimum spacing of 3.5 ft is recommended to minimise the occurrence of punchouts. This concept of narrow crack spacing being more prone to punchout has been accepted. Hence, all the available CRCP design algorithms are based on this concept. However, since treated base/non-erodible base is now provided in CRCP, this theory has some discrepancies with the real CRCP performance especially in Texas. In this study, an extensive field evaluation was conducted for the number of punchouts recorded in TxDOT pavement management information system (PMIS). Out of 1472 punchouts, 232 punchouts that developed in major metropolitan Districts in TxDOT were surveyed and evaluated to determine whether punchouts have a relationship with closely spaced transverse cracks and the resulting load transfer efficiency (LTE). Field survey and testing results show that the majority of distresses in CRCP have been caused by quality issues of either materials or construction in the vicinity of transverse construction joint and repair joint.

IMPACT OF CONCRETE MATERIAL INPUTS ON PERFORMANCE OF CONTINUOUSLY REINFORCED CONCRETE PAVEMENT

Continuously reinforced concrete pavement (CRCP) is increasingly being used in the United States based on its longer service life with minimal maintenance. CRCP provides excellent performance for heavily loaded traffic volume, if designed and constructed properly. The performance of CRCP is evaluated based on punch-outs and pavement roughness according to the Pavement ME (mechanistic-empirical) Design procedure which is the state-of-the-art pavement design tool. Design of CRCP is dependent on various factors including traffic, climate, material inputs and pavement geometry. This study focuses on evaluating the effects of concrete mechanical and thermal properties and traffic volume on CRCP performance. CRCP design simulations were conducted using Pavement ME Design software version 2.3 to evaluate the effects of material input data on CRCP performance and it was observed that there is significant difference between the performance predictions with time series data in comparison to the default data. The impact of material inputs is more significant on punch-outs distress as compared to the pavement roughness. This necessitates the importance of lab tested material inputs for accurate design of CRCP. The impact of traffic volume on CRCP performance was also evaluated and it was found that with increase in traffic volume, the pavement distresses increases and the performance decreases.

Non-Destructive Evaluation of Crack Initiation and Propagation in Continuously Reinforced Concrete Pavements

Transverse crack pattern significantly affects performance of continuously reinforced concrete pavement (CRCP). However, field and modeled crack spacing are based on visual surveys of fully developed transverse cracks visible on the slab surface. Because of the difficulties in detecting incipient cracks in concrete slabs, the effect that such cracks may have on CRCP performance is not currently considered. To address this issue, this paper presents a non-destructive evaluation methodology based on an ultrasonic linear-array system for detection of incipient cracks in CRCP slabs. Two ultrasonic signal-processing techniques were used. First, the Hilbert Transform Indicator was used to identify the presence of damage in the concrete slab indicating potential crack locations. Then ultrasonic image reconstructions of these locations were used to further evaluate crack presence. The methodology was applied to four sections of an experimental short CRCP composed of 50-m long slabs – short in comparison to traditional CRCP. The locations of 58 potential incipient cracks were identified updating the short CRCP crack spacing; 10 of these incipient cracks were confirmed as surface-visible cracks in later visual surveys. Additionally, the methodology shows potential to detect undesired crack patterns such as cluster and Y-cracking before the cracks emerge on the slab surface.

Experimental evaluation of crack width movement of continuously reinforced concrete pavement under environmental load

This study investigates movements of transverse crack width of the continuously reinforced concrete pavement (CRCP) subjected to environmental loads such as changes in temperature. To this end, in-situ experiments were carried out at several highway CRCP sections. The crack width movements were analyzed along the vertical, transverse and longitudinal directions to comprehensively understand the crack width behaviors of CRCP. The effects of design related variables such as steel ratio and base layer type and performance related variables such as crack spacing and crack occurrence time on crack width movements were evaluated. Based on the findings from this comprehensive experimental study concerning crack widths, suggestions were proposed to improve the performance of CRCP.

Experimental analysis of curling behavior of continuously reinforced concrete pavement

This study investigates the vertical deformation called the curling of continuously reinforced concrete pavement (CRCP) and its relationships with crack spacing and temperature variation across the slab depth known as the temperature gradient. To this end, in-situ experiments are carried out at a full scale highway test section of CRCP. Two slab segments with different lengths (0.75m and 2.0m) and a free end expansion joint are chosen to cover a full spectrum of vertical slab movements that define the curling motions of CRCP. Test results showed that the slab segments and the expansion joint curled corresponding to the temperature gradient. The maximum curling displacements occurred along the shoulder side slab edges and those were prominent at the expansion joint and then at the transverse cracks. The curling displacements along the longitudinal joint side were smaller and those along the mid-slab were the smallest. The curling displacements at the expansion joint were not dependent on the length of CRCP. Although the curling motions of CRCP were not large enough to directly worsen the surface smoothness, suggestions were proposed to even improve the overall performance of CRCP.

Field Application and Performance of Continuously Reinforced Concrete Pavement via Mechanical Tube-feeding Method

PURPOSES : The field application and performance of continuously reinforced concrete pavement (CRCP), constructed by using the mechanical tube-feeding method, are evaluated in this study. METHODS: The location of the rebar was evaluated by using the MIRA system. The early-age CRCP performance was evaluated via visual survey, in which the crack spacing and crack width were examined. RESULTS: The location of longitudinal reinforcing bars was evaluated via MIRA testing and the results showed that the longitudinal rebars all lie within a given tolerance limit () of the target elevation. In addition, owing to the low temperature when the concrete was pured, the crack spacing in the Dae-Gu direction is slightly wider than that of the Gwang-Ju direction. Almost all of the crack spacings lay within the range of 1.0 m~3.0 m. A crack width of

Mesoscale analysis of continuously reinforced concrete pavement behavior subjected to environmental loading

Continuously reinforced concrete pavement (CRCP) behavior due to temperature and moisture variations was analyzed using a mesoscale model consisting of coarse aggregate, mortar, and an interface transition zone (ITZ). The effects of the modulus of elasticity and thermal coefficient of the coarse aggregate and the strength at ITZ were evaluated. The results indicated that the coarse aggregate modulus and the drying shrinkage of the concrete had the most significant effect on the development of nonstructural distresses. Using a coarse aggregate with a lower modulus and reducing the drying shrinkage of concrete are thus expected to improve CRCP performance.

Non-destructive Performance Evaluation of Experimental Short Continuously Reinforced Concrete Pavement

As a proposed long-term pavement solution for bus stops and corridors in highly urbanized areas, four experimental continuously reinforced concrete pavement (CRCP) sections with different percentages of longitudinal steel were built in Sao Paulo, Brazil. The pavement sections are only 50 meters long each, a short construction length in comparison to traditional CRCP, which is normally built as long as the construction process allows. A four-year cracking survey of the experimental sections showed that the shorter section length, perhaps due in part to the lack of anchorage, results in a cracking pattern unlike that of the CRCP with traditional lengths. Additionally, two non-destructive tests were carried out to evaluate the structural performance of the experimental sections. First, deflection tests using a falling weight deflectometer (FWD) were conducted to measure the load transfer efficiency (LTE) across all cracks and to determinate slab parameters by backcalculation. Second, dynamic load tests to obtain the concrete stresses under a known load. The results show that the LTE values are adequate (above 90%) in all sections, despite its distinct crack pattern and that tensile stresses at the bottom of the slab are within critical strength values for the concrete. The results from this experimental study are discussed in light of the current literature for CRCP design and performance.

Implications of zero-stress temperature for the long-term behavior and performance of continuously reinforced concrete pavement

The excellent performance of continuously reinforced concrete pavement (CRCP) has been well known. Over the years, various efforts are underway to further improve the long-term performance of CRCP in terms of material, design, construction, and quality control. According to the national mechanistic-empirical pavement design guide (MEPDG) developed as part of NCHRP 1-37A, one of the material factors with a substantial effect on the long-term performance of CRCP is zero-stress temperature (ZST) of early-age concrete. However, there is no documented evidence that the long-term performance of CRCP depends on ZST. In this paper, implications of ZST for the long-term behavior and performance of CRCP are investigated. To accomplish this objective, a series of field evaluations was made in seven experimental CRCP sections with known material properties, design details, and early-age temperature histories, all of which are as old as 7–22years after construction. Performance indicators such as transverse crack spacing, crack width, and typical CRCP distresses, namely punchout and spalling, were evaluated and then compared with the ZST to find a possible correlation between ZST and resulting CRCP performance. Results revealed that there is no strong correlation between them, which suggests needed improvements to the current MEPDG considering more realistic CRCP behavior.

Mechanism of Transverse Crack Development in Continuously Reinforced Concrete Pavement at Early Ages

The transverse crack in continuously reinforced concrete pavement (CRCP), more specifically transverse crack spacing and crack widths, has been cited as one of the most important pavement structural responses determining CRCP performance. Efforts have been made to predict crack spacing and crack widths for given environmental conditions and traffic loading, pavement structure, and material properties, with the primary objective of developing rational CRCP designs. However, that most transverse cracks develop at or near transverse steel implies substantial interactions between transverse steel and other factors causing transverse cracks. These interactions have not been fully incorporated in the theoretical models developed so far to predict transverse crack spacing and crack widths in CRCP. This study investigated the interactions between transverse steel and other factors and identified the mechanisms of transverse crack development at or near the transverse steel. Drying shrinkage and temperature drop in concrete cause concrete volume contractions in all directions (not just transverse and longitudinal, but vertical directions as well). Interactions between concrete volume contraction vertically and transverse steel cause larger concrete tensile stresses at or near transverse steel than at other areas and cause a higher probability of transverse cracks near transverse steel. Traditionally, subgrade drag theory has been used in the design of transverse steel even though current practice is to place just enough transverse steel to support longitudinal steel during concrete placement. If transverse cracks have such substantial effects on CRCP performance as currently thought, interactions between transverse steel and other factors should be considered in the design of optimum transverse steel.

Spalling related to Coefficient of Thermal Expansion (CoTE) of Continuously Reinforced Concrete Pavement in Texas

Concrete volume changes due to temperature and moisture variations (environmental loading) are severely restrained in Continuously Reinforced Concrete Pavement (CRCP) by longitudinal reinforcement and base friction, resulting in numerous transverse cracks, which are held tight by primarily longitudinal steel. Tight transverse cracks provide good load transfer at transverse cracks, ensuring good performance of CRCP. In general, an adequate amount of longitudinal steel and base friction used in CRCP will restrain concrete volume changes to an adequate level, keeping transverse cracks tight and providing good CRCP performance. In Texas, the performance of CRCP is excellent; however, severe spalling problems have been observed in CRCP sections where a certain type of coarse aggregate was used, resulting in costly repairs and traffic delays. This study investigated the causes of severe spalling problems in CRCP in Texas. Fourteen CRCP sections with severe spalling and 10 sections with no spalling distress were identified. A minimum of two cores were taken from each section and concrete material properties, including Coefficient of Thermal Expansion (CoTE) and modulus of elasticity, were evaluated. Test results indicate a strong correlation between spalling and concrete CoTE. Concrete with a CoTE larger than 9.9 × 10-6/°C (5.5 × 10-6/F) is quite prone to severe spalling. On the other hand, CRCP sections with a concrete CoTE smaller than 9.9 × 10-6/°C showed almost no spalling problems.

연속철근 콘크리트 포장 단부 및 수평균열 거동 실험적 분석

This study was conducted to evaluate the necessity of the anchor lug system in continuously reinforced concrete pavement(CRCP) by comparing longitudinal displacements of CRCPs with and without anchor lugs, and to investigate the effect of horizontal cracking on CRCP performance by measuring the vertical displacements. The measurements before and after the anchor lug section was separated were conducted for 12 days in June, and for 14 days in August after the abrupt displacements according to cutting disappeared, respectively. This short term measurement results showed that when anchor lugs were installed, a daily displacement variation at any location was less than 0.1mm; therefore, longitudinal movements were negligibly small. When there were no anchor lugs, longitudinal displacements mainly occurred near the free end and the displacement variation was small; therefore, an expansion joint system seems to be employed at a CRCP terminus without installing anchor lugs. However, further studies are needed to verify the terminus behavior due to annual temperature changes. The horizontal crack width variation was ignorable and did not affect the vertical displacement of the slab. Therefore, the horizontal crack did not delaminate the slab and did not seem to reduce the structural capacity and performance of CRCP.

Effects of Design and Construction Factors on Continuously Reinforced Concrete Pavement Performance

In order to study the effects on the performance of continuously reinforced concrete pavement (CRCP) of some factors, eleven CRCP test sections were designed and constructed in Yanwei Expressway in China. The factors considered included concrete material, base configuration, epoxy coated of steel, transverse steel orientation, the depth of longitudinal reinforcement and the active cracks spacing. Concrete properties tests, early age cracking monitor and falling weight deflectometer tests were all carried out in these test sections. Furthermore, the field investigations to several other CRC pavements having been open for years in China were carried out also and cluster cracking and punchout distress were considered as the performance criteria of CRCP. Finally, the effects on CRCP performance of some factors were discussed. Results show that, the CRCP performance when the separating layer between the concrete slab and cement treated base is asphalt concrete is better than that when the separating layer is paraffin, and the thicker the asphalt mixture separating layer the better the CRCP performance; the modification of transverse steel skew angle can improve the CRCP performance; the concrete material, transverse steel skew and base have more effects on cluster cracking than the separating layer between concrete slab and base does; and the active cracks at the spacing of 1 to 5 m can prevent the occurrence of natural cracks between them.

Characterization of Transverse Cracking Spatial Variability: Use of Long-Term Pavement Performance Data for Continuously Reinforced Concrete Pavement Design

Mechanistic-empirical design procedures for continuously reinforced concrete pavement (CRCP) require characterization of variations in major design parameters so that a new or rehabilitated pavement can be designed for a desired level of reliability. Transverse cracking is an important CRCP design parameter affecting the prediction of crack width, crack load transfer efficiency, and critical stresses leading to longitudinal cracking and punchout development. The primary focus of this study was to investigate spatial characteristics of transverse cracking occurring in CRCP and to develop a theoretical model that would provide a means for systematic characterization of transverse crack spacing variability along the pavement length. Long-term pavement performance distress data were utilized to analyze transverse crack spacing characteristics for CRCP sections. From the results of the field data analysis, a theoretical model utilizing a Weibull distribution was developed to characterize the along-the-section transverse crack spacing frequency distribution. This theoretical model could be incorporated into the mechanistic-empirical procedures for CRCP structural design. The relationship between transverse crack spacing characteristics and punchout development and the location of the longitudinal cracks, which are a punchout precursor, were also analyzed using field survey data. Conclusions derived from field data analysis and the theoretical model presented here will be of interest to practicing engineers and researchers involved in CRCP design and performance modeling.

Field Performance of Continuously Reinforced Concrete Pavement in Illinois

Reviewed are the design and performance of continuously reinforced concrete pavement (CRCP) in Illinois. Illinois has built more than 4267 two-lane km (2,650 mi) of CRCP on the Interstate system since the mid-1950s. CRCP has been constructed on nearly all urban freeways in the Chicago area and has shown excellent performance under severe weather and heavy traffic conditions. The effect of key design and construction parameters on long-term CRCP performance is investigated by using a database based on field surveys conducted from 1977 to 1994 compiled by the Illinois Department of Transportation. Analysis of the data shows the following variables have significant effects on performance: longitudinal reinforcement content (greatest effect of all variables), slab thickness (also very significant), traffic load applications, depth of reinforcement, base type, and D-cracking of concrete. CRCP built with tubes or chairs exhibited overall about the same performance. Experimental field studies in Illinois showed that depth of reinforcement has a large effect on crack width and, eventually, on punchouts. Specifically, the investigation indicated that CRCP sections with a slab 178 mm (7 in.) thick and steel content less than 0.6 percent developed the most structural failures. CRCP sections with a slab 254 mm (10 in.) thick and steel content from 0.7 to 0.8 percent developed the fewest failures. However, all the CRCP sections in this study, regardless of thickness designs and steel content, typically have carried more traffic than they were designed for and have lasted longer than their design traffic life.

Numerical Modeling of Continuously Reinforced Concrete Pavement Subjected to Environmental Loads

Continuously reinforced concrete pavement (CRCP) performance depends on, among other factors, the characteristics of early developing cracks caused by environmental loads. The primary objective is to evaluate effects of design, materials, and construction variables on the characteristics of cracks in CRCP when subjected to environmental loads. A mechanistic model is developed using finite element formulations. Concrete and longitudinal steel are discretized using the plane strain and the frame elements, respectively. Various bond stress and slip models between concrete and longitudinal steel and between concrete and the underlying layers are developed using the spring elements. The creep effect is also included using the effective modulus method. CRCP responses from the model vary depending on the concrete and steel bond-slip models. An accurate bond-slip model needs to be investigated further by experiments to increase the accuracy of the mechanistic model. Concrete creep has beneficial effects on CRCP responses. The thermal coefficient of concrete has significant effects on CRCP responses. Using concrete with a low thermal coefficient will improve CRCP performance. Longitudinal steel variables—the amount of steel, bar diameter, and steel location—are important design variables that influence CRCP behavior. For given environmental conditions, an optimum steel design can be developed using the model developed.