Horizontal/Subsurface Infrastructure & Transportation

Hi,
I was wondering if there is a new unconventional source of aggregates that can be used for construction as a substitute to virgin rocks?
This is a school project, but I found it really interesting to me since I want to do a transportation so that new aggregates can be used.
Thank you 
Madhat

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Muhamad Madhat S.M.ASCE
San Antonio TX
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Muhammed,

Do you mean for asphalt or concrete?

Bob

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Robert Scancella P.E., M.ASCE
Chief Engineer CEI
Bayville NJ
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​Take a look at recycled concrete aggregate.

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John Levitt P.E., M.ASCE
Associate
Grapevine TX
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You should look into recycled glass. There is a market for the reuse of clear recycled glass, but colored glass has a limited market because it has to be sorted (which is generally not economical).  The broken glass (glass cullet) can be used in transportation projects. Also, there is a product called foam glass gravel or foam glass aggregate, where they take the glass cullet, heat it up and introduce air to make a product that looks like "lava rock" you might use in a gas grill. It is used as a lightweight aggregate.

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Peter Narsavage P.E., M.ASCE
Geotech Engr
Columbus OH
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It depends on the end goal of your project and in  what application the replacement aggregate would be used.  Since you mentioned transportation, cold in place reclamation, hot in place reclamation, and full depth reclamation are all options that recycle some, or all, of a pavement section to create a stabilized base course.  The pro's to these methods are reusing the materials in place, which reduces costs of virgin material (it doesn't typically eliminate the need for raw aggregate), reduces waste and emissions, and allows for the correction of deficiencies of a pavement.  One of the biggest cons is the specialized equipment needed.  

Here's a link to the FHWA Pavement Recycling Guidelines:
https://www.fhwa.dot.gov/pavement/recycling/98042/index.cfm

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Chase Henrichs EIT, A.M.ASCE
Rogers AR
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​There are several non-conventional aggregate materials that are currently being used in various applications.  There is a bit in the literature you should review before embarking on a research.  These include crushed glass, recycled asphalt, recycled tires, and expanded shale (lightweight).  Fly ash has also been used in the past, but environmental issues have largely curtailed its current use. Good luck with your project.

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Michael Byle P.E., D.GE, F.ASCE
Tetra Tech Inc.,
Langhorne PA
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​Hi Madhat,

PennDOT specifications allow for use of metallurgical slag.   (waste from iron and steel production)  See Section 703:
http://www.dot.state.pa.us/public/PubsForms/Publications/Pub_408/408_2016/408_2016_3/408_2016_3.pdf

Air- and water cooled slags are treated differently.   They can be slightly unstable chemically and therefore you'll notice there is a requirement to exposed slag to weather for a period of time before it can be used as aggregate.  

There has been much research into use of glass as a construction aggregate.   Shredded tires have been considered too, though I don't think that got very far. 






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David Cooper P.E., M.ASCE
Pittsburgh PA
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Rocks having the needed specific gravity are generally cheap, do not deteriorate or absorb water, do not incur air into the concrete, and are found in masses in concentrated areas, so there is not a strong drive to use a replacement aggregate, especially one that weakens the concrete. Waste materials are not as dense as are needed to serve as intended for good quality concrete where compressive strength is desirable.

There are some who are trying to find ways to use waste materials, such as tires, for coarse aggregate, but rubber weakens the compressive strength by more than 30%, although this could work for some applications, such as sidewalks or residential slabs on grade. But then there is the cost for shipping the tires from tire dumps, handling, shredding, etc. of the used tires, when we usually have the rocks already at the plant where the concrete is being made. Although a noble cause to reduce used tire waste, it results in inferior quality and higher cost of concrete.

Here is a link to a paper on using rubber as coarse aggregate: https://www.codot.gov/programs/research/pdfs/2013/rubberconcrete.pdf

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William Norman P.E., M.ASCE
Structural Engineer
Keeler-Webb Associates
Carmel IN
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​Muhammed,

The Federal Highway Administration did tons of studies in the'70sand '80s about the use of non-aggregrate materials in highway construction. One involved the use of municipal incinerator residue, both fused and unfused. The FHWA is a really good source for this sort of material.

Mike Taylor

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Michael Taylor Aff.M.ASCE
PRESIDENT
Doylestown PA
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Here's a new twist . . .
https://www.giatecscientific.com/knowledge-center/bioconcrete-mushrooms/?utm_campaign=ConcreteHubSept&utm_source=email&utm_source=Giatec+Scientific+Inc&utm_campaign=3c45d862e3-EMAIL_CAMPAIGN_2017_09_20&utm_medium=email&utm_term=0_70e0ef79db-3c45d862e3-341740653

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Kim de Rubertis P.E., D.GE, F.ASCE
Consulting Engineer
Cashmere WA
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Original Message:
Sent: 09-19-2017 11:06
From: Michael Taylor
Subject: Source of aggregates that can be used for construction as a substitute to virgin rocks

​Muhammed,

The Federal Highway Administration did tons of studies in the'70sand '80s about the use of non-aggregrate materials in highway construction. One involved the use of municipal incinerator residue, both fused and unfused. The FHWA is a really good source for this sort of material.

Mike Taylor

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Michael Taylor Aff.M.ASCE
PRESIDENT
Doylestown PA
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------Original Message------

Hi,
I was wondering if there is a new unconventional source of aggregates that can be used for construction as a substitute to virgin rocks?
This is a school project, but I found it really interesting to me since I want to do a transportation so that new aggregates can be used.
Thank you 
Madhat

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Muhamad Madhat S.M.ASCE
San Antonio TX
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Check with producers in the area to find out what are economical options.

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Melanie Fiegen P.E., M.ASCE
Project Engineer
American Engineering Testing, Inc.
Saint Paul MN
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