Pavement characteristics

Pavement characteristics such as rutting, evenness and deformation directly influence the signal recorded by any WIM sensor and limit the accuracy of the measurements. Cracking may also reduce the WIM sensor durability and affect its response. 

With respect to rutting, measured by a 3 m beam, COST 323 (1997) classifies the sites to excellent, good and acceptable when the rut depth values are 4, 7 or 10 mm, respectively. 

The surface evenness, determined using the International Roughness Index, for the abovemen-tioned site classes is 0-1.3,1.3-2.6 and 2.6-4.0 m/km, respectively. Evenness may be expressed in terms of APT rating (French profilometer) and respective range values are given in COST 232. 

Surface evenness or smoothness may also be measured in accordance to AASHTO M 331 (2013) so that the WIM system complies with the performance tolerance required by ASTM E 1318 (2009). 

As for deformation in the case of flexible or semi-flexible pavement, it can be measured with a deflectograph with a 13 t axial load at 2.0 to 3.5 km/h (quasi-static deflection) or a falling weight deflectometer with a test load of 5 t, at a reference temperature of 20°C (dynamic deflection). The range of deflection values per site class is given in COST 323 (1997) (Jacob et al. 2002). 

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For similar pavement characteristics the use of this new S/A binder allows conventional aggregates to be replaced by low quality aggregates which are available on the spot. Moreover, with graded aggregates, the thicknesses of layers can be reduced as a result of the better characteristics of pavement. This is particularly interesting for the strengthening works. 

The accuracy of WIM systems generally depends on a number of factors. Some of them depend on the system selected, particularly on the weight sensor used. Others are consequent to WIM technology and are related to the road geometry, pavement characteristics and environmental characteristics or requirements. 

There are various factors affecting the performance of a WIM system. Some of them are related to the selected device, particularly the weight sensors used and related technology. However, the performance of a WIM system is greatly affected by the choice of the WIM site and the environmental characteristics at the selected site. In relation to the choice of site, the location and road geometry, the pavement characteristics are of great importance as well. 

The pavement inventory has a supportive and informative character however, it is absolutely necessary for pavement management. The minimum pavement characteristics to be recorded are as follows ... 

The mix proportions for concrete paving mixtures are determined by attaining optimum characteristics of the mix in both the plastic and hardened states. The designed mixture can be properly placed and consolidated, finished to the required texture and smoothness, and will have the desired properties necessary for pavement performance. Concrete paving mixtures should be... 

Abrasion and erosion. The dust-loaded wind has an erosive action and contributes to a physical disintegration of rock surfaces or to a polishing of the components of the desert pavement, giving them a characteristic patina desert varnish) and shape (ventifacts). 

Because of the pourability of SAS mixtures, whose slump characteristics can range from 2-6 inches (ASTM Test Method C-143), pavement thickness control could be a problem necessitating the use of forms as in cement construction. Flowability of the mixes induced an... 

The pavement modelling allows to introduce into the model the temporal evolution of the size distribution of materials at the bed surface. By a progressive decrease of the probability density function of the lift force, this model successfully predicts the temporal decrease in mass flux that occurs with the presence of coarse particles at the surface. The rate of this decrease depends on the flow velocity and the characteristics of the particles. In order to improve the accuracy of the estimation of fugitive particle emissions with a wide size distribution, it is necessary to take into account this temporal decrease. 

Time-Temperature Shift Characteristics. Temperature is a major environmental influence on viscoelastic pavement response. The VESYS IIM program can handle material properties as a function of temperature variations. The computer input command BETA relates the time-temperature shift factor, au to the temperature variable for the pavement materials. This relationship is given by ... 

Some of the research activities of the Bureau of Public Roads include physical and chemical testing of paving mixtures, road materials, and soil materials the design and characteristics of nonrigid pavements and concrete pavements and related topics. 

This study of a test pavement using recycled HMA, in which the penetration of the old bitumen had been adjusted using new HMA, confirmed the durability of such a pavement and showed that it could maintain a comparatively good level of utility even after 15 years and 3 months of use. Also, with respect to the physical properties, we have found that the bitumen deterioration of layers of the HMA subject for public use was comparatively small and that the repeated reuse of pavement is indeed possible. Such a high evaluation of pavement recycling from the viewpoint of both utility and physical characteristics should broaden the possibilities for expansion into re-recycling. 

Use Coating asphaltic pavements, foundry sand cores, shell molding and corrosion-resistant materials of construction. Since furfural is readily obtainable by heating pentosan-containing products such as corncobs with mineral acid, these resins are inexpensive and have great potential use where products with their characteristics are required. 

Spatially variable applications of herbicide can be made in fallow or widely spaced row-crops, such as maize or soya beans, by using spectral reflectance type detectors to determine the presence of weeds, and to actuate a spray application system directly. This approach has been developed commercially both in Australia (Felton, 1995), and in the USA, and considerable savings in herbicide use have been demonstrated - see also Chapter 3. The same approach has recently been developed in Europe for use in amenity areas, where the presence of weeds in pavements and gravel paths can be detected by systems working on spectral characteristic criteria. 

A 1-mile test road was constructed in Tillsonburg, Ontario in 1972 to evaluate the performance of several mix compositions as a pavement base. Four mix compositions were placed as base 3V6, 5V2, and IV2 in. thick to evaluate the performance characteristics of the material under heavy traffic conditions. 

The sulfur based marking paints have shown outstanding wear characteristics on asphalt and concrete pavements 54), They performed better than standard paints in all climates and weather when tested in residential communities, rural areas, and in parking lots, as well as on busy highways and in major metropolitan areas. Some of the advantages of sulfur paints are summarized in Table V. Relatively sophisticated application equipment which automatically dispenses reflecting beads was developed and tested in North America and Europe. 

Dore G, Konrad JM, Roy M, Rioux N (1995) Use of alternative materials in pavement frost protection material characteristics and performance modeling. Transp Res Rec 1481 63... 

Apart from the above commonly used soil characteristic parameters, there are also the shrinkage factors, such as shrinkage limit (S), shrinkage ratio (R), the volumetric change (VC) and linear shrinkage (LS). These characteristic parameters are not often used in pavement engineering projects. A detailed description of the test procedure to determine the above parameters can be found in AASHTO T 92 (2009). 

Two other characteristic parameters that are rarely used in pavement engineering are the liquidity index (Ii) and the consistency index (Iq). These indexes are defined by the following equations ... 

The typical property of PA is the high air void content (usually >18%), as well as the high number of interconnecting voids. Because of the above two characteristics, there is quick drainage of surface rainwater and a reduction of the tyre/pavement. 

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