Page 385 - New Trends in Eco efficient and Recycled Concrete

340 New Trends in Eco-efficient and Recycled Concrete

Table 12.1 Leaching, accumulated emissions
2
2
Components Cumulative emissions (mg/m ) Limit of inert material (mg/m )
Ba 171.34 600
Cr 7.02 150
Cu 2.07 50
Mo 1.23 15
Pb 0.64 100
Zn 1.88 200
Co 0.31 25
V 1.16 250
Br 0
Cl 2491 20,000
2015 25,000
SO 4
F 0 1500

The leaching components of the porous concrete were analysed by carrying out
the specific test defined by the NEN 7345 standard.
According to the results obtained in the leaching tests, in Table 12.1 it can be
seen that no leachate of heavy metals exceeded the value defined as the inferred
limit, that is, classified as an inert material, defined by the NEN 7345 standard. A
category 1 material, inert material, does not present any environmental restriction.
The Vasco government (Spain) has used slag from aggregate steel for its use in
maritime works, specifically in the quay of Punta Solana (Fig. 12.4). The results
obtained—physical, chemical, mechanical and environmental—complies with the
technical directives for its application, and for that reason the concrete made with
steel aggregate can be catalogued as an inert material.

12.3 Leaching assessment of recycled concrete

In recent years, the use of different alternative materials—recycled aggregates, fly
ash, plastic waste and glass waste, etc.—have been studied in the production of con-
crete to improve the negative impact on the environment. This increase in the pro-
duction of recycled concrete, has forced research on not only the mechanical
properties of these concretes, but also the need to investigate the potential environ-
mental impact, such as the problems caused through leachates; specifically the pos-
sibility of leaching heavy metals and other elements and molecules that can
contaminate the aqueous medium with which it is in contact (Marion et al., 2005).
One of the problems presented by the use of both conventional and recycled
materials in concrete is the natural degradation that occurs in concrete, both by the
effect of natural water and aggressive environments (Alexander et al., 2013).
Depending on the application for a particular concrete, it could be exposed to deg-
radation caused by a minor impact of pure water, and to a greater degree by acidic