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Relationships between bearing capacity and moisture content were studied in the Danish Road Testing Machine (ALT-facility) (Krarup, 1995). A typical Danish pavement was built in the facility, and for almost one year the only condition that was changed was the level of the water table. No load was applied except for FWD — measurements. The […]

The deterioration of strength, stiffness and resistance to the development of per­manent deformation, or the reduction in pavement life, with increasing moisture levels is a common observation. Trial pavement studies in which the water content of the construction has been changed and reduced performance observed are quite numerous. In recent years work in Finland has […]

Examples of variation of resilient modulus and permanent deformations of subgrade soils with moisture content are presented in Figs. 10.15 and 10.16. Figure 10.15 presents results obtained on a clayey sand (14% fines, optimum moisture content wOPM = 8%). Figure 10.16 presents results obtained for a silt (85% fines, optimum moisture content wOPM = 14%). […]

Unbound granular materials, which are continuously graded materials containing fines, are also sensitive to moisture. Examples of influence of moisture on the Fig. 10.8 CBR values related to moisture (water) content and compaction curves for typical soils: (a) well-graded silty sand with clay, (b) uniform fine sand, (c) heavy clay (Head 1994). @ 1996, copyright […]

10.4.1 Laboratory Results Wetting of unsaturated soil reduces the suction in the soil, the pore pressure ap­proaches the pore air pressure and the effective stress is reduced. Because of this, increasing moisture is associated with decreases in shear strength, stiffness and re­sistance to plastic deformation in all soils and aggregates and we can observe a […]

There are many ways of evaluating pavement structural capacity or adequacy and it is very common to perform deflection measurements with non-destructive testing equipment (COST Action 325, 1997). Once again, there is usually no knowledge of the pore pressure or pore suctions in the soil or pavement layer being assessed, so a total stress interpretative […]

A general overview of conventional and some advanced numerical models used in practice has been given in Chapter 9, Section 9.4. Therefore, tests needed for the parameters of these models will now be presented. • Resilient behaviour models о Routine pavement design model: in practice much routine pavement design is carried out as catalogue — […]

As shown in Chapter 9, Section 9.5, a complete description of a material’s be­haviour necessitates an effective stress approach with the pore pressures (or pore Number of load pulses Number of load pulses Fig. 10.3 Typical results from permanent deformation testing where the accumulated axial strain is shown as a function of the number of […]

The repeated load triaxial testing (RLT) (also known as the cyclic triaxial test) method is commonly used to establish the mechanical characteristics of granular materials. During the testing, a cylindrical specimen is compacted to a desired level and then tested by applying confining and vertical stresses. Two variants exist: • a constant confining pressure (CCP) […]

Although there are a wide variety of tests for assessing soils and road materials, any serious investigation will need to know the mechanical behaviour of these materials when subjected to repeated loading that simulates the effects of trafficking and under moisture conditions (water content and suction) that simulate that found in the layers of the […]