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 from problems directly connected with the temperature of a mixture, the effects of wrongly adjusted equipment during placement may be observed. Now and again errors in laying and the effects of an unsuitable mixture temperature superimpose onto each other. These problems may be divided as follows:
• Manufacture and transport
• Unsuitable temperature of an SMA ingredients during manufacturing and storing in a silo
• Wrong methods of transporting a mixture
• Laying
• Improper temperature of the supplied mixture
• Adjustment errors by the paver and in general methods of laying
Infrared cameras are increasingly being used to analyze thermal problems. Results of such research efforts may be found in several publications (Pierce et al., 2002; Stroup-Gardiner et al., 2000; Willoughby et al., 2001).
