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Figure 11.21 schematically represents a phenomenon caused by the improper dis­tribution of a mixture with augers. The distribution of a mixture along a paver screed should be checked. If the mixture is not properly distributed across the full width of the paver screed, streaks of porosity may become obvious. Another cause may be the location […]

This defect appears in a continuous way along the edge of a layer (Figures 11.17 and 11.18). It is mainly brought about by the following: FIGuRE 11.13 Formation of streaks or mixture pulling due to incorrect setup of paver screed segments. FIGuRE 11.14 The effects of an incorrect paver setup, temperature in degrees Fahrenheit. (Photo […]

Let us suppose that an adequately hot mixture is delivered to the job site. Nevertheless, badly adjusted paver elements (in the given examples, badly arranged screed seg­ments) may bring about the formation of porous areas in the course (streaks). Figure 11.13 presents an example of streaks pulled by a paver during laying. Figure 11.14 presents […]

The laying of too cool a mixture may result in a course with a considerably large amount of air voids (see Section 11.6). That is an obvious matter; however, quite often the accelerated cooling of a mixture takes place in particular areas during its laying. Such places have been defined as having porosity of different […]

When it is cold and the construction site are far away, we usually console ourselves with the idea that the mixture is hot inside so the cool crust may be somehow stirred into the hot mix and warmed up in the paver. The mix really is hot inside, as shown in Figure 11.12. Typical cracks […]

When storing a finished, hot mixture in a silo, the mixture closest to the walls of the container is subject to gradual cooling. As storage time increases, the amount of cool mixture is likely to rise substantially. If the SMA contains modified binder, its stiffening process proceeds much faster. Moreover, we may face additional trouble […]

Most questions related to maintaining a suitable temperature during the mixture’s manufacture have been regulated by commonly known technical specifications (e. g., standards, guidelines). These questions are discussed in Chapter 9. Simply speaking, there are two main problematic instances in the matter of SMA manufac­ture temperatures—when the temperatures are too low or when the temperatures […]

Thermal problems occurring during the manufacture and placement of SMA are often underestimated, and yet they can lead to significant defects in a new course and reduce its working lifetime. It has already been indicated in Section 11.6 that the placement of a cool SMA mixture may result in an excessive content of voids. Aside […]

SMA surface seepage is directly related to excessive porosity of a compacted mixture (see Chapter 12) and the condition (watertightness) of the course situated just under the SMA. When assessing the watertightness of an SMA course, one must not forget that water permeability is determined not only by the contents of voids on the surface […]

Just as it is possible to find an SMA course that is too closed, so too it is possible to find a course that has too high a void content. This problem may occur over very large areas, which are marked by excessive porosity. Local porosity over smaller areas, is described in Sections 11.8.2.3 through […]