Case Study on Secondary Building Materials for a Greener Economy

Abstract

Half of global material consumption involves mineral material. The circularity is still low so that the enhanced use of secondary building material is required to close loops. Three different secondary building materials are discussed based on exemplary research results: construction and demolition waste (C&D waste), soil-like material, and incineration bottom ash (IBA). Focus was placed on the environmental compatibility of the materials examined mainly by standardized leaching tests. C&D waste was investigated after a wet treatment using a jigging machine, and soil-like material and IBA were characterized with respect to their material composition. Their environmental compatibilities in particular were studied using standard leaching tests (batch tests and column tests). It was concluded that soil-like material can mostly be utilized even when the precautionary limit values set are exceeded by a factor of less than two. For C&D waste, the fine fraction below 2 mm and the content of brick material is problematic. IBA fulfills quality level “HMVA-2” following German regulations. Improved levels of utilization might be achievable with better treatment technologies.

Assessment of the Long-Term Leaching Behavior of Incineration Bottom Ash: A Study of Two Waste Incinerators in Germany

“…Further, the decline in pH in the leaching tests was faster for the outdoor samples than for the samples stored indoor. The alkaline pH values are due to the presence of CaO and Ca(OH) 2 in IBA, which reacts with CO 2 from the air or in rain forming CaCO 3 [47]. As a result, pH values decrease to lower values.…”

“…To save scarce landfill volume, today's aim in thermal waste treatment is to also use the mineral fraction of IBA. The most important use pathway of IBA is as secondary building material [47]. The requirements for the use of IBA in Europe were reviewed by Blasenbauer et al [65].…”

“…The use of IBA as aggregate in concrete was studied (see e.g., [67]), but it is not well-developed in practice due to the presence of alkali salts, fine Al particles which could evolve hydrogen, and other disturbing substances. The main areas of application are landscaping (on landfill sites) and road construction, thus helping to save natural resources such as sand and gravel [47].…”