×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*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.

Students Click Here

Jobs

siliceous or carbonate
2

siliceous or carbonate

siliceous or carbonate

(OP)
if i don't specify the type of aggregate what will i get? is it dependent on the region? is one more expensive than the other? not sure i have ever seen a mix design that indicates it.

RE: siliceous or carbonate

Unless you have a special application that requires a very specific kind of aggregate, what type of aggregate you get most often depends on what is economically available in a given region. Specifications normally specify aggregate properties that can be met by wide variety of aggregates. Normally, it's best to start with ASTM C-33 or your local State DOT specs (in the USA, equivalent agencies elsewhere), evaluate the spec, and then just specify exceptions or additions to the standard requirements as may be needed for your specific application.

If ASTM C-33 is used, sometimes local aggregates may not qualify under the grading requirements. However, within C-33 there are exceptions to the grading requirements such that an aggregate may be considered C-33 compliant even if it does not strictly comply with the C-33 requirements, but does have a satisfactory service record and is in compliance with the grading specifications of local public works specifying agencies.

Mix designs may not (usually don't) indicate the type of stone unless the type is specified, but do indicate test values that demonstrate compliance with the performance criteria specified.

RE: siliceous or carbonate

Hoa is correct. Aggregate type is not usually stated on mix design. Here's what I require to review a mix design...

1. Aggregate source
2. Statement of test results for no reactivity
3. Fineness modulus and statement of satisfactory historical performance if fineness modulus does not meet C33 requirements
4. Statement of satisfactory historical performance of the specific mix design
5. Gradations
6. Sources of all materials
7. Strength history including moving average
8. Strength gain curve for the mix design

Type of aggregate is dependent upon the area of production. Local or nearby aggregates will be first priority. Imported aggregates will be more expensive.

RE: siliceous or carbonate

(OP)
thanks, I am asking relative to fire rating, as long as i am restrained my cover is typical, when it is an unrestrained the cover needs to be increased.

RE: siliceous or carbonate

Seeing the title I just knew Ron would be one of the responders!

RE: siliceous or carbonate

It is perfectly acceptable, and sometimes necessary, to specify aggregate types. Specifically for exposed applications, the kind of rock is specified for durability, appearance, or thermal characteristics (CTE/COTE). It is seldom specified otherwise, and is usually is just a function of the local sources or ready mix supplier. The easiest way to find out is to call the ready mix companies near the job and ask about the aggregates.

One of the things we are trying to do with ACI 301 is to get changes allowing performance design (and to remove things like slump specification and limitations - but still allow the test for batch-to-batch consistency purposes.) We would like designers to be able to list performance criteria rather than recipes and limits which may or may not work for the application.

RE: siliceous or carbonate

JAE,
I thought the same thing, but had read the first word as "salacious".

RE: siliceous or carbonate

zing!

RE: siliceous or carbonate

JAE and hokie66....I hate being so predictable...busted!!
Hey hokie...aren't all engineering topics "salacious"? bigsmile

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.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources