By John Davis
Asphalt is an amazingly creative substance with a long history of diverse use. It has been used in countless ways for centuries by many different cultures around the world.
Records show that the first use of asphalt was probably by the inhabitants of the Euphrates river valley in southeastern Mesopotamia, which is now Iraq. In early years Iraq was called Sumer or Accad, and later, Babylonia. Many natural deposits of asphalt were found in this region between the Nile river in Egypt and the Indus river in India. (more…)
By John D’Angelo, PhD, P.E.
There has been a growing concern about pavement performance in the U.S. Observations such as “the roads turn gray very soon after paving” and “cracking is showing up sooner than expected” are being voiced.
The types of cracking in the pavements are changing also. Where the issue used to be low-temperature transverse cracks or bottom-up fatigue cracking, now there are more longitudinal cracking in the wheel path and surface raveling. The pavement in the picture is only one-year-old and it is showing severe distress. Many highway agencies are looking for solutions to these problems. (more…)