Pavement design

SAS mixes with S A ratios of 1.0 to 2.5 1.0 are recommended for use in flexible pavement mixture designs, while S A ratios greater than 5 1 can be used in situations requiring rigid pavement designs. A typical SAS formulation is 82 parts sand, 6 parts asphalt and 12 parts sulfur by weight. 

Mix design, performance, and economics have been considered traditionally in pavement design in a largely empirical or intuitive way which does not allow simple comparisons to be made between candidate materials such as concrete and asphalt. A more efficient and consistent means of considering them is warranted because of the current need to use the most economical materials in a rapidly changing market situation. 

Mechanical Characterization of Sulfur-Asphalt. The serviceable life of a pavement comes to an end when the distress it suffers from traffic and climatic stresses reduces significantly either the structural capacity or riding quality of the pavement below an acceptable minimum. Consequently, the material properties of most interest to pavement designers are those which permit the prediction of the various forms of distress—resilient modulus, fatigue, creep, time-temperature shift, rutting parameters, and thermal coefficient of expansion. These material properties are determined from resilient modulus tests, flexure fatigue tests, creep tests, permanent deformation tests, and thermal expansion tests. 

Shell Pavement Design Manual,Pavement and Overlays for Road Traffic , Shell International Petroleum Co. Ltd., London, U.K., 1978. 

Parker, F. Jr. Steel Fibrous Concrete for Airport Pavement Application, International Conferenceon Concrete Pavement Design, Purdue University, February 1977,541-555. 

Yoder EJ,Witczak MW (1975) Principles of pavement design,2nd edn.Wiley,New York... 

Correlations between CBR and index properties of the soil material or DCP value have been established (National Cooperative Highway Research Program [NCHRP] 2001, 2004) and proposed to be used with the new pavement design procedures of AASHTO known as Mechanistic-Empirical Pavement Design Guide (MEPDG) (AASHTO MEPDG-1 2008). 

The plate bearing test is used for the determination of soil bearing capacity with respect to the modulus of surface reaction (k value). The subgrade bearing capacity in terms of k value is used, mainly, in rigid pavement design methodologies. 

For a pavement design study, the above procedure may be repeated for different percentages of moisture contents hence, the curve of resilient modulus versus moisture content is obtained. Upon knowing the representative moisture content of the layer during a pavement s service life, a more representative resilient modulus (Mr) or stiffness modulus (E) can be determined for further calculations. 

The analytical and some semianalytical pavement design methodologies use a fundamental mechanical property for expressing the bearing capacity or strength of the subgrade soil and not the empirical CBR value. This property is the resilient modulus (Mr) or the stiffness... 

Equation 1.1 proposed by Powel et al. (1984) is based on the work carried out by Jones (1958) and is used in the current UK pavement design methodology (Highways Agency 2006). The validity of the equation is restricted to fine soil material with laboratory CBR... 

Correlations between mechanical parameters (M, CBR, k value and R value) and soil classification groups have been developed and presented in tabular-graphical form (Shell International 1985). The table shown in Figure 1.14 may be used to estimate the mechanical properties of a soil material from its classification group. The value obtained may be used in a pavement design calculation but only at its preliminary stage. 

AASHTO MEPDG-1. 2008. Mechanistic-empirical pavement design guide A manual of practice. Washington, DC American Association of State Highway and Transportation Officials. 

Highways Agency. 2006. Design Manual for Roads and Bridges (DMRB), Volume 7 Pavement Design and Maintenance, Section 2, Part 3, HD 26/06. London Department for Transport, Highways Agency. 

Shell International. 1985. Shell Pavement Design Manual. London Shell International Petroleum Company Limited. 

The grading designations are related to the high pavement design temperature at a depth 20 mm below the pavement surface and the low pavement design temperature at the pavement surface. 

Because they are empirical properties, Marshall stability and flow cannot be used in analytical pavement design calculations. 

Requirement Pavements designed for all types of aircraft gross weight... 

Badkowski W, M. Tusar, and L.G. Wiman. 2009. Laboratory and field implementation of high modulus asphalt concrete. Requirements for HMAC mix design and pavement design. Sustainable Pavements for European New Member States (SPENS), Sixth Framework Programme Sustainable Surface Transport. European Commission, DG Research. 

Determination of fundamental mechanical properties and behaviour of asphalts is not only used in analytical pavement design methodologies. Nowadays, their use has been extended to asphalt s mix design, known as performance-based mix design. 

The most commonly used stiffness modulus is the elastic or dynamic stiffness modulus. It is used for ranking bituminous mixtures (asphalts), for estimating their structural behaviour in the road, as data for compliance with specifications requirements and as a property of asphalt for pavement design analytical calculations or procedures. 

Apart from the dynamic modulus, the term resilient modulus, Mr, is also used in the evaluation of the bituminous mixture s quality and as an input for pavement design, evaluation or analysis. Resilient modulus is quite similar to the stiffness value determined by the indirect tension test in CEN EN 12697-26 (2012), Annex C the differences are outlined in Section 7.4. 

The flow number is also used to determine the rut resistance performance of the pavement with the use of AASHTOWare Pavement ME Design Pavement Design and Analysis Software. 

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