This report, not released for publication, is furnished only for review to members of or particip... more This report, not released for publication, is furnished only for review to members of or participants in the work of the CRP. This report is to be regarded as fully privileged, and dissemination of the information included herein must be approved by the CRP.
Backcalculation of layer moduli of jointed concrete pavements (JCP) normally uses the slab-on-gra... more Backcalculation of layer moduli of jointed concrete pavements (JCP) normally uses the slab-on-grade model, which assumes that the concrete slab is flat and in full contact with the subgrade. The shape of a concrete slab, however, is changing due to either seasonal or daily variations of temperature and moisture gradients. This invalidates the commonly used assumption. Falling weight deflectometer (FWD) data collected at various times of a day exhibit significant variations and so do the subsequently backcalculated layer moduli using these data. This paper presents a case study that quantitatively characterizes the amount of change in the daily deflections and backcalculated layer moduli for data collected for JCP sections under the seasonal monitoring program (SMP) of the long-term pavement performance (LTPP) study. This paper also provides a method that accounts for slab curling during the backcalculation process using a finite element model. Pavement engineers shall understand the variations associated with the deflection data and backcalculated moduli for JCP pavements while using the data for pavement rehabilitation/reconstruction design as the material moduli are essential in the structural evaluation process.
The new Mechanistic-Empirical Pavement Design Guide (MEPDG) requires a number of materials-relate... more The new Mechanistic-Empirical Pavement Design Guide (MEPDG) requires a number of materials-related inputs, many of which are not typically measured or tracked. For rigid pavement design, such inputs include the Portland cement concrete (PCC) coefficient of thermal expansion (CTE), Poisson’s ratio, and elastic modulus. For this study, three replicate specimens were prepared for each of 24 concrete/cement paste mixtures and tested at various ages ranging from 7 to 90 days. Aggregates included in the study represented the major aggregate types typically used in Arkansas. Results from the testing effort were collected into a materials library/catalog to be accessed by pavement designers using the MEPDG for Level 1 design efforts. The results show that MEPDG Level 3 default values for CTE are generally suitable for most design applications; values for Poisson’s ratio should be taken from the PCC materials catalog for design; and that default strength-gain curves embedded in the MEPDG, while generally sufficient for design, could be improved. Regression coefficients governing the MEPDG strength gain algorithm were optimized for Arkansas using the data generated in the study.
The new Mechanistic-Empirical Pavement Design Guide (MEPDG) requires a number of materials-relate... more The new Mechanistic-Empirical Pavement Design Guide (MEPDG) requires a number of materials-related inputs, many of which are not typically measured or tracked. For rigid pavement design, such inputs include the Portland cement concrete (PCC) coefficient of thermal expansion (CTE), Poisson’s ratio, and elastic modulus. For this study, three replicate specimens were prepared for each of 24 concrete/cement paste mixtures and tested at various ages ranging from 7 to 90 days. Aggregates included in the study represented the major aggregate types typically used in Arkansas. Results from the testing effort were collected into a materials library/catalog to be accessed by pavement designers using the MEPDG for Level 1 design efforts. The results show that MEPDG Level 3 default values for CTE are generally suitable for most design applications; values for Poisson’s ratio should be taken from the PCC materials catalog for design; and that default strength-gain curves embedded in the MEPDG, wh...
This report, not released for publication, is furnished only for review to members of or particip... more This report, not released for publication, is furnished only for review to members of or participants in the work of the CRP. This report is to be regarded as fully privileged, and dissemination of the information included herein must be approved by the CRP.
Backcalculation of layer moduli of jointed concrete pavements (JCP) normally uses the slab-on-gra... more Backcalculation of layer moduli of jointed concrete pavements (JCP) normally uses the slab-on-grade model, which assumes that the concrete slab is flat and in full contact with the subgrade. The shape of a concrete slab, however, is changing due to either seasonal or daily variations of temperature and moisture gradients. This invalidates the commonly used assumption. Falling weight deflectometer (FWD) data collected at various times of a day exhibit significant variations and so do the subsequently backcalculated layer moduli using these data. This paper presents a case study that quantitatively characterizes the amount of change in the daily deflections and backcalculated layer moduli for data collected for JCP sections under the seasonal monitoring program (SMP) of the long-term pavement performance (LTPP) study. This paper also provides a method that accounts for slab curling during the backcalculation process using a finite element model. Pavement engineers shall understand the...
This report, not released for publication, is furnished only for review to members of or particip... more This report, not released for publication, is furnished only for review to members of or participants in the work of the CRP. This report is to be regarded as fully privileged, and dissemination of the information included herein must be approved by the CRP.
Backcalculation of layer moduli of jointed concrete pavements (JCP) normally uses the slab-on-gra... more Backcalculation of layer moduli of jointed concrete pavements (JCP) normally uses the slab-on-grade model, which assumes that the concrete slab is flat and in full contact with the subgrade. The shape of a concrete slab, however, is changing due to either seasonal or daily variations of temperature and moisture gradients. This invalidates the commonly used assumption. Falling weight deflectometer (FWD) data collected at various times of a day exhibit significant variations and so do the subsequently backcalculated layer moduli using these data. This paper presents a case study that quantitatively characterizes the amount of change in the daily deflections and backcalculated layer moduli for data collected for JCP sections under the seasonal monitoring program (SMP) of the long-term pavement performance (LTPP) study. This paper also provides a method that accounts for slab curling during the backcalculation process using a finite element model. Pavement engineers shall understand the variations associated with the deflection data and backcalculated moduli for JCP pavements while using the data for pavement rehabilitation/reconstruction design as the material moduli are essential in the structural evaluation process.
The new Mechanistic-Empirical Pavement Design Guide (MEPDG) requires a number of materials-relate... more The new Mechanistic-Empirical Pavement Design Guide (MEPDG) requires a number of materials-related inputs, many of which are not typically measured or tracked. For rigid pavement design, such inputs include the Portland cement concrete (PCC) coefficient of thermal expansion (CTE), Poisson’s ratio, and elastic modulus. For this study, three replicate specimens were prepared for each of 24 concrete/cement paste mixtures and tested at various ages ranging from 7 to 90 days. Aggregates included in the study represented the major aggregate types typically used in Arkansas. Results from the testing effort were collected into a materials library/catalog to be accessed by pavement designers using the MEPDG for Level 1 design efforts. The results show that MEPDG Level 3 default values for CTE are generally suitable for most design applications; values for Poisson’s ratio should be taken from the PCC materials catalog for design; and that default strength-gain curves embedded in the MEPDG, while generally sufficient for design, could be improved. Regression coefficients governing the MEPDG strength gain algorithm were optimized for Arkansas using the data generated in the study.
The new Mechanistic-Empirical Pavement Design Guide (MEPDG) requires a number of materials-relate... more The new Mechanistic-Empirical Pavement Design Guide (MEPDG) requires a number of materials-related inputs, many of which are not typically measured or tracked. For rigid pavement design, such inputs include the Portland cement concrete (PCC) coefficient of thermal expansion (CTE), Poisson’s ratio, and elastic modulus. For this study, three replicate specimens were prepared for each of 24 concrete/cement paste mixtures and tested at various ages ranging from 7 to 90 days. Aggregates included in the study represented the major aggregate types typically used in Arkansas. Results from the testing effort were collected into a materials library/catalog to be accessed by pavement designers using the MEPDG for Level 1 design efforts. The results show that MEPDG Level 3 default values for CTE are generally suitable for most design applications; values for Poisson’s ratio should be taken from the PCC materials catalog for design; and that default strength-gain curves embedded in the MEPDG, wh...
This report, not released for publication, is furnished only for review to members of or particip... more This report, not released for publication, is furnished only for review to members of or participants in the work of the CRP. This report is to be regarded as fully privileged, and dissemination of the information included herein must be approved by the CRP.
Backcalculation of layer moduli of jointed concrete pavements (JCP) normally uses the slab-on-gra... more Backcalculation of layer moduli of jointed concrete pavements (JCP) normally uses the slab-on-grade model, which assumes that the concrete slab is flat and in full contact with the subgrade. The shape of a concrete slab, however, is changing due to either seasonal or daily variations of temperature and moisture gradients. This invalidates the commonly used assumption. Falling weight deflectometer (FWD) data collected at various times of a day exhibit significant variations and so do the subsequently backcalculated layer moduli using these data. This paper presents a case study that quantitatively characterizes the amount of change in the daily deflections and backcalculated layer moduli for data collected for JCP sections under the seasonal monitoring program (SMP) of the long-term pavement performance (LTPP) study. This paper also provides a method that accounts for slab curling during the backcalculation process using a finite element model. Pavement engineers shall understand the...
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