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REPORT 
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Publication Number:
FHWAHRT12030
Date: August 2012 
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The information collected from literature was used to identify the independent variables or index properties used to predict the material engineering properties identified in chapter 2. The independent variables that the researchers considered most likely to be included in deriving the prediction models for PCC, stabilized, and unbound materials are listed in table 6 through table 8, respectively.
It was envisioned that more than one prediction model might be required or might be derived with the data available in the LTPP database. Multiple models are significant for use in different projects (e.g., new design versus rehabilitation versus pavement management) or stages of pavement life. For example, flexural strength correlations for PCC materials will be derived using index properties that can be useful during the design stage if mix design or optimization is performed. However, a correlation to compressive strength from a core would be useful for predicting the performance of the asconstructed pavement during the QA stage or in pavement management applications.
Data selection, analyses, and statistical modeling are discussed in detail in chapters 4 and 5 of this report. Predictive models can be based on lab or field test data, such as with the prediction of flexural strength based on compressive strength or index properties. Alternatively, correlations can be drawn to categorical variables, such as with PCC CTE. CTE can be a function of mix components and proportioning or a function of aggregate type. The latter option provides SHAs with the opportunity to recommend default values for CTE (as is being done for the MEPDG).
MEPDG calibration data were included as inputs to develop prediction models for design feature inputs (see chapter 5 for further discussion). These variables include the following:
Material Property 
Constant or Time Dependent 
Independent Variables 
Comments 

Primary Model 
Secondary Model 

Rehabilitation of New PCC Slab 

Compressive strength 
Time dependent 
Aggregate type, cement content, air content, w/c, unit weight, gradation, admixtures, SCMs, and age 
N/A 
Prediction for 28day strength and longterm strength in separate models; strength gain model to be updated 
Elastic modulus 
Time dependent 
Aggregate type, cement content, air content, w/c, unit weight, admixtures, and SCMs 
Compressive strength/ flexural strength 
Prediction for 28day value and longterm values in separate models 
Flexural strength 
Time dependent 
Aggregate type, cement content, air content, w/c, unit weight, admixtures, and SCMs 
Compressive strength 
Prediction for 28day strength and longterm strength in separate models; strength gain model to be updated 
Indirect tensile strength (CRCP only) 
Time dependent 
Compressive strength/flexural strength 
N/A 

CTE 
Constant 
Coarse and fine aggregate type, aggregate CTE, coarse and fine aggregate volume, paste volume, and w/c ratio 
Aggregate type 
Default PCC CTE for each aggregate type and model based on mix design 
deltaT for JPCP and CRCP design* 
Time dependent 
Base type, construction time, PCC index properties, and climatic variables 
N/A 
Data in MEPDG JPCP and CRCP calibration to be used 
Erosion in CRCP design** 
Time dependent 
Base type, index properties and strength of base, and climate (precipitation) 
N/A 
Data in MEPDG CRCP calibration models to be used 
EI—JPCP** 
N/A 
Base type, base properties, and climate (precipitation) 
N/A 
Data in MEPDG JPCP calibration models to be used 
Rehabilitation of Existing PCC Slab 

Compressive strength 
Time dependent 
Same as for parameters used in new design 
Elastic modulus 
Time dependent 
Same as for parameters used in new design 
Flexural strength 
Time dependent 
Same as for parameters used in new design 
N/A = Not applicable.^{}*Construction dependent. **Base dependent but listed in PCC properties because it is considered a design feature for JPCP or CRCP design.
Material Type 
Material Property 
Constant or Time Dependent 
Independent Variables 
Lean concrete and cementtreated aggregate 
Elastic modulus 
Constant 
Compressive strength 
Flexural strength* (for HMA pavement design) 
Constant 
Compressive strength 

Limecementfly ash 
Resilient modulus 
Time dependent 
Unconfined compressive strength or index properties (soil type, Atterberg limits, and gradation) 
Soil cement 
Resilient modulus 
Time dependent 
Unconfined compressive strength or index properties (soil type, Atterberg limits, and gradation) 
Limestabilized soil 
Resilient modulus 
Time dependent 
Unconfined compressive strength or index properties (soil type, Atterberg limits, and gradation) 
All material types listed above 
Unconfined compressive strength 
Time dependent 
Soil type, Atterberg limits, and gradation 
*Construction dependent.
Material Property 
Constant or Time Dependent 
Independent Variables 
Comments 
Resilient modulus determined using the following two options: · Regression coefficients k_{1}, k_{2}, and k_{3} for the generalized constitutive model that defines resilient modulus as a function of stress state and regressed from lab resilient modulus tests. · Determine the average design resilient modulus for the expected inplace stress state from laboratory resilient modulus tests. 
Time dependent 
Soil type, Atterberg limits, maximum dry density, optimum moisture content, gradation, and the percent passing the #200 sieve, P_{200}. 
Analyses will verify several options and combinations of grouping data 
Topics: research, infrastructure, pavements and materials Keywords: research, infrastructure, pavements and materials, Pavements, LTPP, material properties, MEPDG, prediction model, Index properties TRT Terms: research, facilities, transportation, highway facilities, roads, parts of roads, pavements Updated: 09/26/2012
