×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Asphalt: Acceptability of Marshall Flow Test Results

## Asphalt: Acceptability of Marshall Flow Test Results

(OP)
I have to determine whether Marshall Flow values from three pucks prepared from the same sample of hot mix asphalt are acceptable according to the provisions of ASTM D6927 and ASTM C670. The three pucks were prepared by the same operator. The Marshall Flow values are 15, 21 and 26 (0.25mm).

The average of the flows is 20.7 (0.25mm)
The standard deviation is 5.51
The co-efficient of variance of individual measurements is 26.6%

From ASTM D6927 and C670:
Number of samples = 3
Multiplier for Table 2 = 5.7
Co-efficient of variance for acceptance, 1s% = 9%
Maximum acceptable range as a percentage of mean = 51.3%

My question pertains to the calculation of the range as a percentage of the mean.

Method 1

Is the range calculated as the difference between the highest and the lowest values, that is, 11 (=26-15), and then the range as a percentage of the mean is 11/20.7*100 = 53.1%? Therefore, in this case, the range as a percentage of the mean (53.1%) is outside of the maximum acceptable range (51.3%), and the results can be considered suspect.

Or is the range calculated as follows.

Method 2

Flow (0.25mm)
Range as a percentage of mean
15
27.5% (=(20.7-15)/20.7*100))
21
1.4% (=(21-20.7)/20.7*100))
26
25.6% (=(26-20.7)/20.7*100))

In this case, the range as a percentage of mean (1.4% to 27.5%) is within the maximum acceptable range (51.3%) and the results can be considered acceptable.

Any guidance on the above query will be sincerely appreciated.

Thank you.

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!