Consider the following two asphalt binders: PG 70-28 and PG 64-22 (a) Which do y
ID: 1712410 • Letter: C
Question
Consider the following two asphalt binders: PG 70-28 and PG 64-22
(a) Which do you think would be the more expensive binder to specify, and why?
(b) You are preparing a set of project plans for a routine maintenance overlay in the city of Sioux Falls, SD. Not considering cost, which binder (PG70-28 or PG 64-22) do think will provide better performance in terms of rut resistance? Why?
(c) You are preparing a different set of plans for a project to construct a section of new roadway on new alignment in north eastern South Dakota. Which binder (PG 70-28 or 64-22) do you think will provide an asphalt pavement that is less likely to develop low temperature cracking? Why? Do you suggest any other asphalt binder which may work better?
Explanation / Answer
The PG 70-28 grade of bitumen is costlier than that of PG 64-22. Here, PG indicates performance grade and 70 indicates average maximum pavement temperature and 28 indicates minimum average pavement temperature. PG 70-28 will have the more viscosity which is used in the high-temperature environments than that of PG 64-22 grade. Sioux Falls, SD city has lowest temperatures which around 11 degrees Celsius at present. So, the PG 70-28 grade of bitumen is suitable for these conditions which provide better performance in terms of rutting. PG 70-28 grade of bitumen will less likely to cause low temperature cracking. Because it can tolerate the temperatures up to -28 degrees Celsius. PG 76-40 may also work better.