civ3703 assignment 2 - 2014 guides

8/10/2019 CIV3703 Assignment 2 - 2014 Guides

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3. The asphalt modulus is determined in the laboratory using a machine

that applies a load in 40 ms, corresponding to a vehicle speed of 95

kph. If the design speed is not 95 kph, you need to apply a correction

factor. The higher the design speed, the higher the design modulus.

All of the above correction factors have to be applied to the laboratory

modulus (multiplicatively).


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Using the design asphalt modulus for thickness design using Austroads

Charts:

For example, for a full-depth asphalt pavement you can use a chart such as

shown below (mind the asphalt modulus) to find the thickness of asphalt for

the given design traffic (ESA).

For other pavement types, appropriate charts can be used to find the

thickness(es) of pavement layer(s).

Q5

You are provided with this list:

Hints: Find the % AV and % Effective Binder Content by volume.


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You will see that % AV and % Effective Binder Content by volume are

interrelated. Therefore, the calculations may look somewhat lengthy and

complicated. Follow the steps below and try to understand why certain steps

are required before you can get the % AV and % Effective Binder Content by

volume.

1. First, consider information within the red box.

Aggregate mix = coarse aggregate + fine aggregate + filler.

Firstly, calculate % aggregate in total asphalt mass = 100% - % binder

content by mass = P

Then, calculate % mass coarse aggregate in aggregate mix = 60/P . 100% =

Q

Similarly, calculate % mass fine aggregate (R) and % mass filler (S) inaggregate mix.

Note: Q + R + S = 100%

2. Next, calculate the bulk density of the aggregate mix using Eq. 5(2) of

AS2891.8-2005.

3. Using the calculated bulk density in (2) and the supplied maximum

asphalt density and % binder by mass, calculate the % binder

absorbed using Eq. 5(3) of AS2891.8-2005.

4.

The % effective binder by mass can then be calculated using Eq. 5(4)ofAS2891.8-2005.

5. Percent air voids in the specimen can be calculated from Eq. 5(1) of

AS2891.8-2005. But you need to calculate the bulk density of the

specimen first (mass volume). Volume of specimen is calculated

using the mass in air and the mass in water (Archimedes principle

see Eq. (1a) of the supplied notes on Preparation of Specimens for

Marshall Test).

6. Percent binder by volume (effective) is calculated as follows (see

Figure 1 of the supplied notes on Preparation of Specimens for

Marshall Test):

% Volume of (effective binder + aggregate) = (100 AV) = X

Volumetric proportion of effective binder = % effective binder by mass

density of binder = Y

Volumetric proportion of aggregate = % aggregate by mass bulk

density of aggregate mix = Z

Hence, % volume of effective binder = X . {Y/(Y + Z)}


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You should comment on this value, whether it is good or bad, why

good/bad, etc. Read Section 5.5 of the Study Book.

7. Maximum theoretical density, VMA and VFB can be obtained from Eq.

5(5), 5(6) and 5(9) of AS2891.8-2005.

8.

The use of the Shell Nomograph for estimating the stiffness modulusof asphalt was discussed in Recording 28 - CIV3703 - Week 8 -

Session 3. Note that the stiffness modulus of a recovered binder is

higher than that of a fresh binder due to field oxidation/ageing (as

discussed in the lecture, field ageing process is often simulated using

the Rolling Thin Film Oven Test or RTFO in the laboratory).

4.

civ3703 assignment 2 - 2014 guides

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