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Title:
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Leaching behaviour of artificial aggregates : EU project BRST-CT98-5234
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Author(s):
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Published by:
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Publication date:
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ECN
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1-12-2001
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ECN report number:
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Document type:
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ECN-C--01-014
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ECN publication
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Number of pages:
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Full text:
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190
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Download PDF
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Abstract:
In the framework of EU project "Utilising innovative kiln technologyto recycle waste into synthetic aggregate" (BRST-CT98-5234), the leaching
behaviour of artificial aggregates has been studied to assess its environmental
compatibility in the various stages of its use. Since the conditions
are very different for the different applications, the assessment calls
for a variety of
different leaching test conditions. The pH dependence test is used to
cover important differences in pH environment to which the materials
are exposed to as wel1 as for an assessment of the acid buffering capacity
of the material. It is found that artificial aggregate has a low buffer
capacity, which makes it sensitive to externally imposed pH conditions.
Utilisation and storage exposed
to acidic conditions needs to be avoided. The results of the pH dependence
test and column leaching test are mutually consistent while the CEN
TC 154 method systematically provides lower values.
The artificial aggregates studied here wil1 not adversely affect the
concrete in its service life. The main issue for aggregate use is the
recycling and the "end of life" condition, when the material becomes
construction debris. Not metals, but oxyanions, such as Cr VI and Mo
are most relevant under the recycling, reuse and "end-of life" condition.
This is based on the criteria
set by the Dutch Building Materials Decree as this is the only legislation
available to make such an environmental judgement.
A concise test has been applied to assess crucial aspects of leaching
for different production mixes. Also concluded is that results from
the CEN TC 154 test are different from more elaborate characterisation
tests. Alternative compliance tests that do give consistent results
with the more elaborate characterisation tests are available.
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