Describe the component of emulsified asphalt (asphalt emulsion) and discuss how asphalt emulsions work as a binder in asphalt mixture. (5 marks)

↑

▷ Содержание

⇐ ПредыдущаяСтр 5 из 7Следующая ⇒

21.As a materials engineer working for a highway department, what standard PG asphalt binder grade would you specify for each of the conditions shown in Table 1 (show all calculation and fill in the table)? (10 marks)

Table 1

Case

7-day pavement

Max. pavement temperature

Recommended PG grade

Mean, oC

Std. Dev.,

oC

Mean, oC

Std. Dev.,

oC

50%

Reliability

98%

Reliability

1.5

-29

2.5

PG 46-34

PG 46-34

-18

PG 52-22

PG 58-28

2.5

PG 64-10

PG 70-10

1. Average 7-day Max Pavement Design Temperature ≥ 43+2*1.5 = 46 ºC

Minimum Pavement Design Temperature ≤ -29-2*2.5 = -34 ºC

2. Average 7-day Max Pavement Design Temperature ≥ 51+2*3 = 57 ºC

Minimum Pavement Design Temperature ≤ -18-2*4 = -26 ºC

3. Average 7-day Max Pavement Design Temperature ≥ 62+2*2.5 = 67 ºC

Minimum Pavement Design Temperature ≤ 10-2*2 = 6 ºC

22.Describe the component of emulsified asphalt (asphalt emulsion) and discuss how asphalt emulsions work as a binder in asphalt mixture. (5 marks)

Emulsion constituent: asphalt cement + water + emulsifying agent

Asphalt emulsion due to its viscosity and bending properties sticks aggregates in the asphalt mixture:

· Mixing – asphalt cement, water and emulsifying agent are mixed together

· Breaking – the process of separating the asphalt and water

· Curing – the process by which the asphalt expels water and dries to a film on the aggregate or surface

23.As discussed in the Class note, there are several ways to alter asphalt concrete (AC)’s moisture susceptibility to water damage. Describe how to improve moisture susceptibility resistance of AC in terms of AC components. (5 marks)

· Increase asphalt content

· Higher viscosity asphalt

· Clean aggregate of dust and clay

· Change aggregate gradation

· Add anti-stripping additives

- liquid

- portland cement or lime

24.What are the various grades [systems] of asphalt cement? (4 marks)

· Penetration Grading (PEN)

· Viscosity Grading (AC)

· Aged Residue Grading (AR)

· Performance Grading (PG)

Познавательные статьи:



Техника прыжка в длину с разбега

Организация работы процедурного кабинета

Области применения синхронных машин

Оптимизация по Винеру и Калману