ASPHALT BINDERS AND ASPHALT MIXTURES - Materials for Civil and Construction Engineers - page 387

9.11 As a materials engineer working for a highway department, what stan-

dard PG asphalt binder grade would you specify for each of the condi-
tions shown in Table P9.11 (show all calculations and fill in the table)?

Table P9.11

Seven-Day Maximum Minimum Pavement Recommended PG Grade

Pavement Temperature, °C Temperature, °C

50% 98%

Case Mean, °C Std. Dev., °C Mean, °C Std. Dev., °C Reliability Reliability

1 46 1.5 - 34 2

2 56 2 - 15 2.5

3 66 2 8 1.5

9.12 For the following temperature conditions, calculate the proper Super-
pave grade for both 50% and 98% reliabilities (show your calculation).
Seven-day maximum pavement temperature of 46°C with a standard
deviation of 2°C.
Minimum pavement temperature of 19°C with a standard deviation
of 4°C.
9.13 What are the differences between CRS-2 and SS-1 emulsions?
9.14 Discuss how asphalt emulsions work as a binder in asphalt mixtures.
9.15 What are the components of hot-mix asphalt? What is the function
of each component in the mix?
9.16 What are the objectives of the asphalt concrete mix-design process?
9.17 Why is it important to have an optimum binder content in HMA?
What would happen if a less-than-optimum binder content is used?
What would happen if more than the optimum value is used? What
is the typical range of binder content in HMA?
9.18 Explain why the strength of asphalt concrete is not necessarily the
most important property of the material.
9.19 An asphalt concrete specimen has a mass in air of 1249.3 g, mass in
water of 735.8 g, and saturated surface-dry mass of 1250.2 g. Calculate
the bulk specific gravity of the specimen.
9.20 As part of mix design, a laboratory-compacted cylindrical asphalt
specimen is weighed for determination of bulk specific gravity. The
following numbers are obtained:

Dry Mass in
Mass when submerged in
Mass of Saturated Surface Dry

Air = 1204.5 grams

water = 689.4 grams

1 SSD 2 = 1211.3 grams

a. What is the bulk specific gravity of the compacted specimen
b. If the maximum theoretical specific gravity of the specimen
is 2.531, what would be the air void content of the specimen in
percent?

1 G mb 2

1 G mm 2