Diseño de pavimentos

TENAX
Technical Reference GRID-DE-2

DESIGN OF FLEXIBLE PAVEMENTS WITH TENAX GEOGRIDS

GRID-DE-2 Feb. 2001

TABLE OF CONTENTS

1. INTRODUCTION ..........................................................................................................1 2. AASHTO DESIGN METHOD .......................................................................................1 3. DESIGNREQUIREMENT..............................................................................................3 3.1 Design Variables.................................................................................................3 3.2 Performance Criteria ...........................................................................................6 3.3 Material Properties for StructuralDesign..............................................................7 3.4 Pavement Structural Characteristics.....................................................................7 4. MODIFIED AASHTO METHOD WITH TENAX GEOGRIDS ......................................8 5. DESIGN EXAMPLE .......................................................................................................9 6. DESIGN WORKSHEET FlexPave..................................................................................11 7. REFERENCES ................................................................................................................12

GRID-DE-2 Feb. 2001

DESIGN OF FLEXIBLE PAVEMENTS WITH TENAX GEOGRIDS

1. INTRODUCTION This technical note describes the design steps of asphalt concrete flexible pavements, utilizing theAmerican Association of State Highway and Transportation Officials (AASHTO) “Guide for Design of Pavement Structures” 1993. The structural contribution of Tenax Geogrids to the flexible pavement is quantified in the current design method by increasing the structural layer coefficient of the aggregate base course. A design worksheet for pavement design and a design example are provided. Flexiblepavements generally consist of a prepared subgrade layer which is the roadbed soil or borrow material compacted to a specified density. A subbase course is constructed on top of the prepared roadbed, and may be omitted if the subgrade soil is of a high quality. The base course is constructed on the subbase course, or if no subbase is used, directly on the roadbed soil. It usually consists of aggregatessuch as crushed stone, or crushed gravel and sand. On top of the base course is the surface course that typically consists of a mixture of mineral aggregates and bituminous materials. Existing design methods for flexible pavements include empirical methods, limiting shear failure methods, limiting deflection methods, regression methods, and mechanistic-empirical methods. The AASHTO method (1993)is a regression method based on results from road tests. AASHTO published the interim guide for design of pavement structures in 1972, with revised versions in 1981, and 1986, and the current version in 1993.

2. AASHTO DESIGN METHOD The AASHTO method utilizes the term Structural Number (SN) to quantify the structural strength of a pavement required for a given combination of soil support, totaltraffic, reliability, and serviceability
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level. The required SN is converted to actual thickness of surfacing, base and subbase, by means of appropriate layer coefficients representing the relative strength of the construction materials. The design equation used is as follows: SN = a1 ⋅ D1 + a2 ⋅ D2 .m2 + a3 ⋅ D3 .m3 where, ai Di mi = = = ith layer layer coefficient ith layerthickness (inches), and ith layer drainage coefficient (drainage effect on the Asphalt layer is not considered in the AASHTO 93 guide) the subscripts 1, 2 and 3 refer to the asphalt concrete course, aggregate base course and subbase course (if applicable) respectively. The basic design equation for flexible pavements in the AASHTO 93 design guide is as follows:  ∆PSI  log 10   4.2 − 1.5  + 2.32...