Leaching of Carbon Reinforced Concrete—Part 2: Discussion of Evaluation Concepts and Modelling

Abstract

Possible threats on the environment and human health by the leaching of new building materials and composites in contact to water should be prevented from the outset. It is therefore necessary to assess and ensure their environmental compatibility. For irrigated construction elements this is a challenging task, as there is no general correlation between known testing methods and outdoor emissions. A feasible assessment concept is needed for these conditions. In this work the German assessment method for permanently wet building materials is applied on different carbon reinforced concrete (C3) leaching data. Furthermore, emission prediction approaches of the Dutch building Materials Decree and the software COMLEAM are tested. The established methods are not yet suitable to determine the complex long term outdoor emissions of irrigated C3. In order to achieve realistic results in time saving testing methods and to define reasonable release limits, it is necessary to determine and verify the relevant influencing parameters on leaching through intermittent water contact. This research works out leaching patterns and correlations between inorganic substances. It is shown that the input parameters time of exposure, contact time, air temperature, air humidity, runoff and background concentration should be considered to predict the leaching processes from irrigated concrete phenomenologically.

Environmental Impact of Construction Products on Aquatic Systems—Principles of an Integrated Source–Path–Target Concept

“…In fact, façade panels, renders and coatings are exposed to dynamic weather conditions in contrast to constant conditions in the laboratory. For the leaching behaviour of inorganic constituents from concrete, plasters and renders, the DSLT does not necessarily deliver higher release compared with the field [42,43]. Figure 3 demonstrates the differences for arsenic, zinc and vanadium from concrete sheets tested in the laboratory and outdoors.…”

“…A transfer of the derived functions to substances with similar leaching behaviour was successfully conducted by varying a constant in the regression term. Yet, the functions are to be verified by further tests, and a method to determine the constant on a laboratory scale should be developed [43].…”

“…Mathematical models were applied to describe leaching processes under outdoor conditions, i.e., regression approaches combined leaching data from field experiments and weather conditions [27,43], and a slope-based analysis of leaching curves was intended to identify periods that are controlled by different processes [57].…”

Measurement of the Environmental Impact of Materials

“…Weiler et al studied the leaching behavior of irrigated building structures made of carbon-reinforced concrete with accelerated simulations at a laboratory scale [ 4 ]. Evaluation concepts are discussed in the second part of the work [ 5 ] to align simulation results to field conditions and enable the establishment of threshold values.…”

“…Leaching tests represent a common thread in the submissions to this Special Issue [ 3 , 4 , 5 , 6 , 13 , 14 , 15 , 16 ]. The underlying mass transfer principles of column leaching tests are discussed by Liu et al [ 14 ], and Sakanakura et al [ 15 ] showed that adsorption parameters can be determined in batch leaching tests with varying liquid–solid ratios.…”