![transit chart overlay in iphemeris transit chart overlay in iphemeris](https://iphemeris.com/wp-content/uploads/mag-ge-harmonic.png)
Further, it may be noted that there always exists a temperature profile and moisture content profile (that is, variation along the depth of the pavement). For design purpose, it is generally assumed that the temperature affects the stiffness of the asphalt layer and the moisture content affects the stiffness of the unbound granular layer and the subgrade.
![transit chart overlay in iphemeris transit chart overlay in iphemeris](https://i.ytimg.com/vi/ixC8_pR5mvs/maxresdefault.jpg)
In the design guidelines such variations are accounted either (i) considering expected/equilibrium value of the temperature and the moisture content during the design period or, (ii) by dividing the total design period into certain time intervals and considering the effects of temperature and moisture content (in terms of incremental damage) for these time intervals. Įnvironmental parameters used in pavement design primarily include variation of temperature and moisture conditions (including freezing and thawing situations) during the service period of the pavement. Thus, appropriate (i) choice of pavement material for the individual pavement layers, (ii) mix design for each of these materials and (iii) estimation of engineering properties (which are used as design input), are integral parts of the process of pavement design. From pavement design stand-point, both (i) good fatigue performance, as well as (ii) high stiffness modulus of the asphalt mix, are desirable. For example, with the increase of the asphalt binder content in the asphalt mix, the fatigue performance may improve, but the stiffness modulus value may start decreasing. However, sometimes a pair of desirable properties may show conflicting trends with the variation of a constituent of the mix. The composition of a pavement material is finalized through appropriate mix design, so that the desirable levels of various engineering properties of the material are achieved. The engineering properties of a pavement material depends on the relative composition of its constituents. These materials show complex response when subjected to load, temperature and moisture variations. While there are design considerations involved in a pavement from the geometric, functional and drainage aspects, the structural design indicates estimation of appropriate thicknesses of the pavement layers.ĭifferent kinds of materials are used to construct individual layers of a pavement structure. An asphalt pavement is made up of multiple layers, namely subgrade, sub-base, base, surfacing and wearing course.