Objective and Scope The objective of this technical committee is to provide a focal point and working group with various types of pavement expertise to develop and recommend AASHTO guides, policies, and standards for the design, rehabilitation, accelerated testing, and management of pavements and shoulders. The technical committee is composed of members from the Subcommittee on Design, members from the Subcommittee on Materials, and one each from the Standing Committee on Planning, Subcommittee on Construction, Subcommittee on Maintenance, and the Standing Committee on Aviation. Publication Responsibility The technical committee is responsible for developing and updating the following documents:. Publications currently under review for possible adoption:.
Guide to Pavement Type Selection Unless otherwise noted, the above publications can be purchased from AASHTO's Online. ME Design Guide Information.
Next Meeting The next Joint Technical Committee on Pavements meeting is scheduled for Tuesday, April 25 and Wednesday, April 26, 2017 at the Mayflower Park Hotel, 405 Olive Way, Seattle, WA 98101.: (206) 623-8700 www.mayflowerpark.com. Meeting Minutes The following are the official minutes from recent technical committee meetings:.
May 10-11, 2016: (includes presentations). May 5-6, 2015: (includes presentations). April 29-30, 2014: (includes presentations). April 30-May 1, 2013: (includes presentations). May 15-16, 2012: (Adobe pdf format, 11.5k).
May 10-11, 2011: St. Louis, MO -Coming Soon-. May 25-26, 2010: (Adobe pdf format, 12.3 mb)(Includes all Presentations). May 27-28, 2009: (Adobe pdf format, 64k), Presentation:. May 13-15, 2008: (Adobe pdf format, 68k). September 19-21, 2007: (Adobe pdf format, 60k), Presentations: (Adobe pdf format, 1.1m).
April 12-13, 2007: (Adobe pdf format, 168k). Winter 2006: (Word format). Winter 2003: (Adobe pdf format, 44k).
Fall 2002: (Word, 106k). Spring 2002: (Word, 68k). Summer 2001: (Word, 58k).
Apr 6, 2011 - This book provides approaches to pavement design including design and management principals, procedures for new construction.
Where: E c equals PCC elastic modulus equals PCC compressive strength If no compressive strength data are available (or cannot be assumed), assume E c = 27,500 MPa (4,000,000 psi), which corresponds to a compressive strength of 34.5 MPa (5000 psi). PCC modulus of rupture (flexural strength). The modulus of rupture (S’ c) is typically obtained from a flexural strength test. Slab depth.
The pavement structure is best characterized by slab depth (D). The number of ESALs a rigid pavement can carry over its lifetime is very sensitive to slab depth. As a general rule, beyond about 200 mm (8 inches) the load carrying capacity of a rigid pavement doubles for each additional 25 mm (1 inch) of slab thickness. Drainage coefficient.
Rigid pavement is assigned a drainage coefficient (C d) that represents the relative loss of strength due to its drainage characteristics and the total time it is exposed to near-saturation moisture conditions. Generally, quick-draining layers that almost never become saturated can have coefficients as high as 1.2 while slow-draining layers that are often saturated can have drainage coefficients as low as 0.80. If subsurface drainage is expected to be a problem, positive drainage measures should be taken. In general, the use of drainage coefficients to overcome poor drainage conditions is not recommended (i.e. More slab thickness does not necessarily solve water-related problems).
Because of the peril associated with its use, often times the drainage coefficient is neglected (i.e., set as C d = 1.0). Serviceable life. The difference in between construction and end-of-life is the serviceability life. The equation compares this to default values of 4.2 for the immediately-after-construction value and 1.5 for end-of-life (terminal serviceability). Typical values used now are:.
Post-construction: 4.0 – 5.0 depending upon construction quality, smoothness, etc. End-of-life (called “terminal serviceability” and designated “p t“): 1.5 – 3.0 depending upon road use (e.g., interstate highway, urban arterial, residential). Load transfer coefficient (J Factor). This accounts for.
Essentially, the lower the J Factor the better the load transfer. The J Factor for the was estimated to be 3.2. Typical J factor values are as shown below. Condition J Factor Undoweled PCC on crushed aggregate surfacing 3.8 Doweled PCC on crushed aggregate surfacing 3.2 Doweled PCC on HMA (without widened outside lane) and tied PCC shoulders 2.7 CRCP with HMA shoulders 2.9 – 3.2 CRCP with tied PCC shoulders 2.3 – 2.9. The modulus of subgrade reaction (k) is used to estimate the “support” of the PCC slab by the layers below. Usually, an “effective” k (k eff) is calculated which reflects base, subbase and subgrade contributions as well as the loss of support that occurs over time due to erosion and stripping of the base, subbase and subgrade. Typically, large changes in k eff have only a modest impact on PCC slab thickness.
Outputs The 1993 AASHTO Guide equation can be solved for any one of the variables as long as all the others are supplied. Typically, the output is either total or the required slab depth (D). In design, the rigid pavement equation described in this chapter is typically solved simultaneously with the rigid pavement ESAL equation.
The solution is an iterative process that solves for ESALs in both equations by varying the slab depth (D). The solution is iterative because the slab depth (D) has two key influences:. The slab depth (D) determines the total number of ESALs that a particular pavement can support.
This is evident in the rigid pavement design equation presented in this section. The slab depth also determines what the equivalent 80 kN (18,000 lb.) single axle load is for a given load. Therefore, the slab depth (D) is required to determine the number of ESALs to design for before the pavement is ever designed. The iterative design process usually proceeds as follows:.
Determine and gather rigid pavement design inputs (Z R, S o, D PSI, p t, E c, S’ c, J, C d and k eff). Determine and gather rigid pavement ESAL equation inputs (L x, L 2x, G). Assume a slab depth (D). Determine the equivalency factor for each load type by solving the ESAL equation using the assumed slab depth (D) for each load type.
Estimate the traffic count for each load type for the entire design life of the pavement and multiply it by the calculated ESAL to obtain the total number of ESALs expected over the design life of the pavement. Insert the assumed slab depth (D) into the design equation and calculate the total number of ESALs that the pavement will support over its design life. Compare the ESAL values in #5 and #6.
If they are reasonably close (say within 5 percent) use the assumed slab depth (D). If they are not reasonably close, assume a different slab depth (D), go to step #4 and repeat the process. Design Utility This design utility solves the 1993 AASHTO Guide basic design equation for rigid pavements. It also supplies some basic information on variable descriptions, typical values and equation precautions.