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Leaching issues in recycled aggregate concrete 347

Figure 12.7 Application of EPA Method 1315 using a semi-dynamic tank leaching
procedure [EPA 1315].

The dimensions of the container and the samples are chosen so that they meet the con-
ditions, and the monolithic samples must be cylindrical or parallelepipedic.
The pH and the specific conductance of each leachate are determined and samples are
collected for the subsequent chemical analysis of each. Each sample should be pre-
served accordingly to the determinative methods to be performed.
The concentrations of the others are analysed as a function of time by studying the
cumulative release. These data are necessary to determine the mass transfer of each
component and to relate them to the potential contamination.
This test is quite complicated to apply since it is necessary to postpone enough extrac-
tions of water comma many times during the different application points and is a good
test to study long-term monoliths.

The standard CEN/TS 15862 should be applied in regular cases to study all the
results of different types of concrete. In specific cases, EA NEN 7375 could be
applied to study long-term leaching behaviour of monolith concrete.

12.3.5 Leaching limits in the assessment of Recycled Concrete:
testing the tank

One of the most important problems when it comes to studying the leaching of
recycled concrete is the possibility of classifying the pollotant potential of the tested
materials.
There are limits for leaching tests as those applied on unbound aggregates (UNE
12457-4) or in percolation tests (CEN/TS 16637-2). But there are no clearly estab-
lished limits for the leaching tank test for monolithic specimens.
The limits that apply to the leachates generated from monolithic test CEN/TS
15862 are those that are admitted for drinking water consumption. If we combine
international directives, we must take data from the EPA (United States
Environmental Protection Agency), WHO and Directive 98/83/CE of Europe,
respectively (Table 12.3).