Reinforced Concrete Pavement Research Articles

Research on Early Cracking of the CRCP in the Tunnel under Low Temperature Difference

Calculate and analysis influence of the temperature field for Continuously Reinforced Concrete Pavement design. The temperature and crack of pavement are tested, so that the temperature changing and early cracks development inside the tunnel have been got. Studies have shown that: the tunnel temperature changes slowly, the temperature difference is small. In the first two days after concrete paving, the internal temperature of the slab was significantly higher than the ambient temperature, 79% of early cracking appears in this stages; Panel temperature rise because of the cement hydration. Strain increases in process of the growth of the concrete strength and shrinkage, the cracks appears. The number of cracks in the first two days accounted for 50% of the total number in 7 days, only the number of the second day accounted for 37.59%. Crack width accounted for 60.5% of the total, which is mainly concentrated in 0.1 mm and 0.2 mm. The crack spacing is mainly concentrated in 2m to 8m, accounted for 76.8% of all. The maximum crack spacing is 84 m, the minimum is only 0.5m.

The Use of Recycled Aggregates in Continuously Reinforced Concrete Pavements (CRCP)

The use of recycled aggregates in concrete has increased in recent decades. Increasing scarcity of natural aggregates and the growing ecological importance promote this evolution. The first test section in Belgium of a two-layer continuously reinforced concrete pavement (CRCP) with recycled aggregates in the substrate layer was built on the highway E34/N49 in 2007. Horizontal cracking at the level of the reinforcement showed up after only a few years. This is a problem which was never seen before in CRCP and was probably due to the use of recycled aggregates. Therefore it is important to understand the impact of recycled aggregates on concrete. Recycled aggregates are a two-component material consisting of natural aggregates and adhering mortar. The adhering mortar is more porous than the rock particles which insures a higher water absorption and lower density. In addition, they have a lower abrasion loss in the Los Angeles-test and less resistance against weather and temperature changes. This is due to, respectively, the less strong mortar content, and the large pores of recycled granulates. A first cause of horizontal cracking can be found in the results of high drying shrinkage, high creep and low modulus of elasticity. These properties insure larger tensions in the concrete layer. In combination with a lower tensile strength it is a possible cause for the horizontal cracking. In addition, the paper reports on laboratory testing concerning the properties of concrete with recycled aggregates and discusses an alternative method to determine the concrete mixture which takes the influence of the adhering mortar into account.

Improvements of Full-Depth Repair Practices for Distresses in Continuously Reinforced Concrete Pavement

The Texas Department of Transportation has by far the most continuously reinforced concrete pavement (CRCP) lane miles in the nation, and sections as old as 50 years are still in service. Having served much longer than intended, some sections are showing distress. Full-depth repair (FDR) is one of the methods used to repair CRCP distresses in Texas. Over the years, various FDR methods have been used, and the effectiveness of each method has varied. In the most widely used FDR method, a full-depth cut is made at a minimum of 1.5 ft (0.46 m) inside the transverse repair boundaries, a partial-depth cut is made at repair boundaries, and the concrete between the cuts is removed to expose longitudinal steel. The method has inherent disadvantages, the longer repair time being the primary one. The full-depth cut FDR method, in which a full-depth cut is made at the repair boundaries and longitudinal tie bars are epoxy grouted into the existing concrete, has advantages over other methods, including a faster operation that minimizes roadway closure time. Because CRCP is normally used in areas with high traffic volume, the maximum time the Texas Department of Transportation allows for the FDR operation is usually 9 h, which makes the full-depth cut method the only acceptable repair method. Factors affecting the effectiveness of the full-depth cut method were investigated with laboratory testing and field evaluations. The method of epoxy injection, keeping the epoxy in the holes after insertion of the tie bars, restoring base support, and the length of the embedded tie bar were the most important variables affecting the performance of FDR. Recommendations were made to revise specifications for FDR and epoxy materials on the basis of these research findings. Implementation of the recommendations should result in improved FDR performance of CRCP.

Investigations on ballastless tracks in tunnel without reinforcement

Ballastless track systems have delivered an optimal performance in the past decades. This ideal comes from the Continuously Reinforced Concrete Pavement or the Jointed Plain Concrete Pavement in road design. It can be deduced that a well-proved system for road pavement is applicable to ballastless track design after certain modifications, which could save materials and simplify the construction work as well. In this paper, a feasibility study of ballastless track forms, in which neither reinforcement nor dowel bars shall be applied have been investigated using Finite Element Analysis. The results show that this idea is feasible in long tunnel with hard and stabile substructure, if a joint spacing less than 4 m can be realized. Meanwhile, these kinds of systems cannot be applied for track with soft substructures such as mass-spring-systems, in which continuous double-layer-reinforcement and sufficient thickness of the track concrete layer are required.

Evaluation of the Benefits of Diamond Grinding of a Continuously Reinforced Concrete Pavement

This paper discusses a study to evaluate the benefits on a continuously reinforced concrete pavement (CRCP) of diamond grinding used specifically for improving pavement functionality in surface macrotexture, skid resistance, roughness, and noise. The effectiveness of diamond grinding in improving those properties is calculated on the basis of in-field observations. The effect of three preexisting conditions (carpet drag, burlap drag, and transverse tining) on the effectiveness of diamond grinding is also evaluated. The results of the analysis indicate that diamond grinding improved the surface macrotexture by 0.6 mm and skid resistance by about 60%. The surface roughness of the diamond-ground sections was, on average, appreciably reduced, from 124 to 80 in./mi. An average overall reduction in noise level of 3.2 dB(A) was evident. A maximum reduction in the region of the noise frequencies (1,000 to 2,500 Hz) was observed, with a maximum noise reduction of 5.6 dB(A) at 1,600 Hz. The grinding operation produced a relatively uniform surface in relation to these properties despite the varying preexisting conditions across the CRCP.

Safety and Durability Pavement in Super Long Tunnel

In order to solve the problem of design and construction of pavement structure in the long tunnel, through the analysis of pavement using domestic and overseas, combined with the factors of primary carrying capacity, small temperature gradient in the long tunnel, the Continuously Reinforced Concrete Pavement(CRCP) is proposed, which has characteristics of better durability, strong structure integrity and comfortable driving. Mini excavator auxiliary framing construction, layered pouring concrete, lap joint construction of welded steel have solved a series of problems of the relatively small space of construction, the lower concrete vibrators affected by the steel mesh and reinforced scene lashing. So continuously reinforced concrete pavement using welded steel fabric can be used as a major road structure in long tunnel.

Improved Mechanistic–Empirical Continuously Reinforced Concrete Pavement Design Approach with Modified Punchout Model

The Mechanistic–Empirical Pavement Design Guide (MEPDG) makes available a mechanistic–empirical punchout prediction tool based on a comprehensive analysis of many design factors in continuously reinforced concrete (CRC) pavement. The punchout model is based on the idea that accumulated fatigue damage induces longitudinal cracking between two narrowly placed transverse cracks as a result of repeated loading, diminished load transfer, loss of support, and environmental stresses. Most factors are considered directly in the punchout prediction except those related to subbase support. For instance, stiffer support conditions reduce deflection, with smaller interfacial shear stresses than subbase shear strength as a result, and thus lower erosion. However, the MEPDG predicts a higher rate of punchouts with increasing k-value because a punchout is assumed to be analogous to longitudinal fatigue cracking. The unfortunate consequence of this assumption is that the predicted rate of punchout might increase as a result of greater curling and warping stresses because of stiffer sublayers or higher k-value situations. The probability of erosion was included to counteract this effect on punchout predictions. A modified mechanistic–empirical CRC pavement design approach is described in terms of a modified punchout model, subbase erosion model, and an enhanced traffic equivalency model. The modified design approach includes expressions for fatigue distress similar to those in the MEPDG. The design also considers partial-depth punchout distress as part of the assessment of punchout distress.

Research on Load Transfer of Continuously Reinforced Concrete Pavement with Hollow Foundation

Based on the equivalence principle of bending deflection and torsional displacement, the concentrated vertical load which acts on the center of a continuously reinforced concrete pavement (CRCP) is translated into an equivalent half-wave sine load by Fourier transform. On the basis of this transform and deformation harmony condition of crack, the equations of load transfer are established. According to the translation principle of the force, the equations of load transfer of adjacent slabs are worked out. With the small deflection theory of elastic thin slabs, the bending deflection and torsional displacement formulas of CRCP under the concentrated vertical load with hollow foundation are deduced, which is verified by the results of finite element(FE). The results show that the characteristic of CRCP after cracking is related to the rigidity factor which is proportional to the spacing of adjacent cracks and the width 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.

Study on Preventing from Deformation Diseases of Dolanit Fiber Asphalt Concrete at Road Intersection

Due to the heavy traffic and channelization, vehicle often brake and park for a long time at the urban road signal intersection, especially at heavy traffic intersection, for which it is easy to present permanent deformation on asphalt pavement. It can significantly improve the technical characteristics of the road intersection with adding Dolanit fiber into asphalt concrete. Based on BISAR3.0 software of applying layered elastic system theory and combined with the surface layer analysis on indoor mechanical property test to Dolanit fiber rein-forced asphalt concrete pavement, the results show that the allowable tensile stress is 0.61MPa. Even if at the condition of overload 50% and emergency braking, there is no shear failure on the Dolanit fiber rein-forced asphalt concrete pavement.

Experimental Study on Water Seepage Rate with Crack Width of Continuously Reinforced Concrete Pavement

In order to discover the water damage mechanism of CRCP, the simulation test was established to study the relationship between crack width and seepage rate. The results show that the seepage rate increases with the widening of crack. For reducing water damage and improving pavement performance, some essential waterproof measures, according to the amount of rainfall, should be taken in designing the CRCP.

Study on Deformation and Stress of CRCP under Concentrated Vertical Load with Hollow Foundation

Based on the equivalence principle, the concentrated vertical load which acts on the Continuously Reinforced Concrete Pavement(CRCP) transverse crack is translated into the equivalent half-wave sine load by Fourier transform. According to the translation principle of the force, the half-wave sine vertical load acting on the CRCP transverse crack is decomposed to the half-wave sine vertical load and the torsion force acting on the center of CRCP. Lastly, the deflection, torsional displacement and stress formulas of CRCP under the concentrated vertical load with hollow foundation are put forward, which is on the basis of the small deflection theory of elastic thin plate and torsion theory. The results show that increasing the slab thickness is the most effective measure to reduce maximal deflection, distortion displacement and stress of CRCP concentrated vertical load with hollow foundation.

Performance of Continuously Reinforced Concrete Pavement Containing Recycled Concrete Aggregates

Between 1986 and 1987, the Illinois Department of Transportation constructed a section of 10-in. continuously reinforced concrete pavement (CRCP) containing recycled concrete aggregate on I-57 near Effingham, Illinois. Functional and structural data, including falling weight deflectometer tests, visual distress surveys, surface profiles, and skid numbers were collected periodically throughout the service life of the pavement. Falling weight deflectometer results indicated that the pavement section exhibited excellent load carrying, with an average load transfer efficiency greater than 90% across the transverse cracks. The prominent distress was longitudinal cracking, which appeared over the reinforcement bars in all lanes. This abnormal cracking pattern had been noted for many years and had been attributed to problems with the original tube feeding process. The section developed a significant amount of localized distresses and patches over its last 5 years as a result of further deterioration of the longitudinal cracking. A petrographic examination concluded that no deleterious alkali–silica reaction had occurred in the pavement and that the air void system had been normal. The mean transverse crack spacing was approximately 1.5 ft, which was significantly shorter than normal CRCP and was attributed to the greater drying shrinkage potential of recycled concrete aggregate. Functionally, the pavement showed good skid resistance and fair-to-good ride quality. The overall performance of this CRCP section exceeded the performance of roughly 50% of the 10-in. CRCP within Illinois in terms of age and 25% in terms of traffic. In June 2010, this CRCP section was overlaid with 3.5 in. of asphalt concrete.

Continuously Reinforced Concrete Pavement

In 2005, the Texas Department of Transportation initiated a rigid pavement database to collect information in preparation for the calibration and potential implementation of the Mechanistic–Empirical Pavement Design Guide (MEPDG) for continuously reinforced concrete pavement (CRCP). Twenty-seven sections, each 300 m (1,000 ft) long, were selected throughout the state. Deflection testing was conducted with a falling weight deflectometer. The information collected included load transfer efficiency (LTE) at small, medium, and large crack spacing for two different seasons, summer and winter. Also collected were crack-spacing information and slab deflections. LTE values for all the cracks were higher than 90% regardless of slab thickness, pavement age, crack spacing, or season. Mechanisms of primary distresses in CRCP were investigated. The investigation tentatively revealed that many distresses identified and recorded as punch-outs in Texas were not actually caused by structural deficiency. Rather, most of the distresses were caused by imperfections in design details, construction or material quality issues, or both. Horizontal cracking appears to be the major cause of distresses in CRCP in Texas. The interactions between longitudinal steel and concrete in response to dynamic wheel loading applications appear to be the cause of horizontal cracking. From the findings, mechanistic–empirical (ME) CRCP design procedures and a calibration function were developed. Because the accuracy of any ME design procedure depends to a great extent on the reasonableness of the transfer function, further efforts will be made to improve that function.

A Study on the Shrinkage Control of Fiber Reinforced Concrete Pavement

Cement concrete pavement provides durable service life and remarkable applicability for heavy traffic. Its purchase being easier than asphalt, cement concrete pavement offers excellent advantages in terms of durability and economic efficiency. However, adequate repair of this pavement is harder than asphalt concrete in case of degradation or damage. Cracking in the concrete pavement is the major cause of such disadvantages and the demand of repair on road sites is growing every day. This emphasizes the urgency to secure technologies for the control of early and longterm cracking. Accordingly, this study evaluates the drying and autogenous shrinkage strains regard to fiber reinforcement in order to reduce cracking of the concrete pavement mix so as to control the damage of the pavement by means of fiber reinforcement. The results show that the drying shrinkage strain can be significantly reduced to about 1/4 through the admixing of 0.2% volume ratio of NY fiber compared to the non-reinforced plain concrete, and that the hybrid fiber reinforcement mix H-N1-ST1 can realize remarkable reduction of the autogenous shrinkage.

Field performance evaluations of partial-depth repairs

Before partial-depth repair using proper materials was implemented, Houston District of Texas Department of Transportation had to repair spalls and punchout constantly in the Continuously Reinforced Concrete Pavement (CRCP) pavements on US290 and SH6. The full-depth repair to address the cracking on US75 did not work well. Spalls, wide, cracks and punchouts due to mid-depth horizontal cracks represent functional and structural distresses in Portland cement concrete pavement. Traditionally, these distresses were repaired by partial-depth repair (PDR). The performance of PDR varies substantially. Two types of polymeric patch materials were used to repair the distresses. Material A is polyurethane-based and Material B is epoxy-based. Material A was used to repair spalls in CRCP. It provided quite satisfactory performance for more than 9 years. Material B was used to repair cracks in jointed concrete pavement and CRCP. Its performance was satisfactory when applied to stable slabs and the loose concrete was completely removed. Compared to full-depth repair (FDR), PDRs utilizing polymeric patch materials are much more cost-effective, and PDR takes much less time than FDR. It is believed that both chip-and-patch and saw-and-patch methods would work as long as the delaminated areas are completely removed and the concrete slabs are stable (e.g. no settlement or movement under moving trucks).

Influence of Mixture Design and Environmental Factors on Continuously Reinforced Concrete Pavement Cracking

The influence of concrete mixture design and environmental factors on cracking in a continuously reinforced concrete (CRC) pavement was documented on Interstate 90 in Hanson County, South Dakota. A project evaluated three mix designs, which were placed in the eastbound direction in 2005. From the study, it was shown that crack frequency was directly related to the initial concrete temperature as specifically contributed by the aggregate in the mix–and a reduced cement content making a less workable concrete. The study recommends an application of curing compound within 30 min to reduce CRC cracking, and wetting the aggregate stockpiles in hot weather to cool them overnight to reduce concrete temperature. Construction of CRC test sections containing at least 510 lb/yd3 of cement with 112 lb/yd3 (15% cement replaced with 18.75%) Class F fly ash is under way to examine the effects of the rate of early strength gain on cracking.

Variation of Crack Width over Time in Continuously Reinforced Concrete Pavement

The primary objective of this paper is to present the findings of field studies that investigated variations in crack widths over time in three continuously reinforced concrete pavement projects in Texas. Also presented are crack width variations through the slab depth. Vibrating wire gauges were installed at three slab depths—top, middle, and bottom—during concrete placement. Transverse cracks were induced at the locations of the gauges, and concrete strains were measured. The ages of the projects varied from 11 months to 2 years, 10 months. Significant variations existed in crack widths along the slab depth. Crack widths were largest at the top and smallest at the bottom. In the test sections of this study, crack widths at the middepth were about three-quarters of those at the top. Crack widths at the top and middepth were a direct function of temperature variations in the concrete at those depths. However, there was a poor correlation between concrete temperatures and crack widths at the bottom. There was clear evidence that moisture variations in concrete have substantial effects on concrete volume changes and crack widths. An immediate decrease in crack widths was observed after rains. Crack widths decreased over time within the time frame of this study. This finding is not consistent with the current theory on crack width variations over time, and further study is currently under way at the University of Texas at Austin to identify the causes. The findings will be reported as they become available.

Analysis of Damage Mechanism of Reinforced Concrete Pavement Joint Sealant

Highway agencies in Thailand select reinforced concrete pavement for highways that have to carry a high traffic volume because of the pavement's durability and ability to support heavy loads with less deformation. Joint sealant is a structural component that interconnects the pavement slabs. Limited information on the joint sealant is available in Thailand. This research proposes to analyze the damage mechanism of the joint sealant by application of the finite element method under the local environment in which it is subjected to different load patterns, temperature, and time periods. Three-dimensional finite element analysis of the joint sealant and its fatigue property are presented in this paper. Displacement of slab edge surface on both sides of the rigid pavement expansion joint by traffic loading and curling effect can cause stress and strain in the joint sealant. This study conducts an experiment to obtain the fatigue property of the joint sealant subjected to the cyclic movement induced by traffic loads and the curling effect in the rigid pavement slabs. Results of sealant behavior analysis under different configurations and damage analysis of joint sealant under fatigue loading are presented in regard to the stress–strain relation and percentage of joint sealant damage with respect to its service life. Case studies are selected to illustrate how an agency could mechanistically determine maintenance frequency of joint resealing.

Analysis of Damage Mechanism of Reinforced Concrete Pavement Joint Sealant

Highway agencies in Thailand select reinforced concrete pavement for highways that have to carry a high traffic volume because of the pavement's durability and ability to support heavy loads with less deformation. Joint sealant is a structural component that interconnects the pavement slabs. Limited information on the joint sealant is available in Thailand. This research proposes to analyze the damage mechanism of the joint sealant by application of the finite element method under the local environment in which it is subjected to different load patterns, temperature, and time periods. Three-dimensional finite element analysis of the joint sealant and its fatigue property are presented in this paper. Displacement of slab edge surface on both sides of the rigid pavement expansion joint by traffic loading and curling effect can cause stress and strain in the joint sealant. This study conducts an experiment to obtain the fatigue property of the joint sealant subjected to the cyclic movement induced by traffic...