The Development of a New Faulting Model in Jointed Concrete Pavement Using LTPP Data
Yu Chen, Texas A&M UniversityShow Abstract
Robert L Lytton, Texas A&M University
Faulting is a major and commonplace distress in Jointed Concrete Pavement (JCP), which can directly cause pavement roughness and adversely influence the ride quality of a vehicle. Faulting also plays an essential role in concrete pavement design. Notwithstanding the importance of faulting, the accuracy and reasonability of the faulting prediction models that have been developed are still controversial. In addition, full understanding of the process of faulting is still uncertain over time. This paper proposed a novel mechanistic-empirical model to estimate faulting depth at joints in the wheel path in JCP. Two stages within the process of faulting were revealed in the model and introduced in this study. To distinguish the two stages of faulting, an inflection point, as a critical faulting depth, was determined directly by this model and suggested to be an indicator of the initiation of erosion for the concrete pavement design. The proposed model was proven accurate and reliable by using Long Term Pavement Performance (LTPP) data. The parameters in the model were statistically calibrated with performance-related factors by the Akaike’s Information Criterion (AIC) method for variable selection and performing stepwise regression.
Long-Term Performance Evaluation of Concrete Pavements Containing Recycled Concrete Aggregate in Oklahoma
Xijun Shi, Texas A&M Transportation InstituteShow Abstract
Anol Mukhopadhyay, Texas A&M Transportation Institute
DAN ZOLLINGER, Texas A&M University
To overcome the challenges associated with natural aggregate shortage and the deposits of construction and demolition waste, recycled concrete aggregate (RCA) has been increasingly utilized in portland cement concrete (PCC) pavement as virgin aggregate replacements. The work in this study involved conducting a performance evaluation of the existing RCA-PCC pavements in Oklahoma from different aspects. These aspects included laboratory determination of mechanical properties, a petrographic examination of the concrete, and a field evaluation using a falling weight deflectometer (FWD) testing and distress surveys to assess pavement behavior. The laboratory testing of the field cores confirmed that addition of RCA into PCC causes reduction in modulus of elasticity and tensile strength; the reclaimed mortar was found to be the primary weak zone through which cracks pass though. The surface condition survey data and analysis of the FWD results match each other, which generally indicate that the RCA JPCP section exhibited lower performance compared to the control JPCP section, but such trend was not as definitive for CRCP. The relatively good performance of the RCA CRCP is because the section was rested on a stronger asphalt concrete base layer. Additionally, the inherent stiffness fundamental to the behavior of CRCP provides a superior level of protection of the base from erosion damage compared to a jointed pavement. Based on the findings, it is verified that erosion-resistant base support and good load transfer are essential design considerations for JPCP made of RCA-PCC. CRCP appears to be more suitable for the use of RCA-PCC.
A Mechanistic Study of Two-Lift Concrete Pavements: Design and Economics
Surya Teja Swarna, Memorial University of NewfoundlandShow Abstract
Kamal Hossain, Memorial University of Newfoundland
Muppireddy Amaranatha Reddy, IIT Kharagpur
Braj Bhushan Pandey, IIT Kharagpur
The government of India has embarked on the construction of major highways with concrete pavements to eliminate frequent maintenance of bituminous pavement, damaged by heavy commercial vehicles and moisture. It is therefore necessary to re-examine the current pavement design with a sound analytical approach. The current practice in the construction of concrete pavement in India is to place pavement quality concrete (PQC) over dry lean concrete (DLC) layer with a bond-breaking layer of 125-micron plastic sheets between the DLC and PQC layers to eliminate possible reflective cracks from the DLC to the PQC layer. Concrete pavement can be bonded to lean concrete (LC) when both layers are laid one after the other with two pavers (“fresh-on-fresh” or “wet-on-wet”). This type of pavement is also known as two-lift concrete pavement (TLCP) and such pavements were constructed in India during the last three years. No readymade solutions are available to compute stresses in such TLCPs. The objectives of the research are manifolds. First, this research determines the stresses in TLCP using a finite-element programming software (ANSYS). Then the design of pavements with TLCP has been introduced using the cumulative fatigue damage method. Finally, the cost of construction for TLCP is determined and compared with that of conventional concrete pavement. It was found that the material cost for TLCP is less than that of conventional concrete pavement because the stresses induced due to both load and environmental effects in TLCP are significantly lower when compared to those on the conventional concrete pavement.
Improvements in CRCP Bonded Concrete Overlay Design
Fei Yu, Texas Tech UniversityShow Abstract
Pangil Choi, Texas Tech University
Hoonill Won, Texas Tech University
Moon Won, Texas Tech University
Many miles of existing Portland cement concrete (PCC) pavement in Texas built in the 1970s and 1980s have already surpassed their design lives, not only in terms of years but more so in traffic applications. There is an urgent need to strengthen the capacity of those pavements to preserve their condition. One of the most cost-effective methods to increase the structural capacity of the CRCP system is the placement of bonded concrete overlay (BCO). Even though the performance of CRCP BCO in Texas has been satisfactory, in one recent project, distresses developed soon after the completion of BCO. Investigations were conducted to identify the causes for premature failures and inadequate BCO design was ascertained as its cause. The design was developed in accordance with the 1993 AASHTO Pavement Design Guide, with a condition survey method as a means to determine an effective slab thickness. The condition survey method does not directly evaluate the structural condition of CRCP; however, for BCO to perform satisfactorily, the structural condition of the existing pavement should be sound. To improve BCO design method, field performance information was analyzed and a deflection-based design method was developed. In this method, a threshold deflection value was selected for 4-in BCO on 8-in CRCP. This threshold value was expanded to include the effects of tied concrete shoulder and other overlay slab thicknesses. The implementation of this method is expected to enhance the performance of CRCP BCO.