Recycling of lightweight concrete

Pilot plant paves the way to the future

Implementation of a zero-waste economy requires feeding back of secondary raw materials into subsequent production runs, which is one of the major challenges all raw material processing industries are facing. This is particularly true for the German construction industry, which consumes mineral raw materials in large quantities whilst also generating the biggest waste stream.

From a scientific and engineering point of view, lightweight concrete opens up the potential for establishing a closed material cycle. For this purpose, further advances need to be achieved in the development of recycled lightweight concretes on the basis of recycled lightweight granular materials and recycled lightweight concrete rubble. It is thus essential to conceive an innovative recycling technology that enables the manufacture of premium recycled products from previously non-recoverable fine fractions from the pumice industry, pure lightweight concrete, and lightweight concrete rubble from demolished buildings. The latter contains secondary constituents typically found in the construction sector. Possible finished products include recycled lightweight granules with defined properties that can be adjusted by setting appropriate raw material and process parameters. A large number of preliminary tests showed that the characteristics of such granules were comparable to those of commercially available expanded clay products. Recycled granular materials should be used as lightweight aggregates in new production runs of lightweight concrete blocks, thus closing the material cycle.

In recent years, experience proved that the rapid transfer of innovative recycling methods into practice has often failed due to the lack of a multi-purpose reference plant. IAB Weimar will be installing such a pilot facility to close this gap between applied research and industrial implementation. This new resource efficiency center of excellence will cover all relevant process steps, including crushing of construction waste, grinding, granulation, and firing in the rotary kiln. It will be available for industry partners to conduct joint research and tests.

Related articles:

Issue 2020-02 Construction rubble

An innovative raw material for lightweight granules with a wide range of applications

Construction and demolition waste, at 89 million tons, is the dominant type of waste in Germany in terms of quantity. These wastes are mainly recycled in earthworks and road construction. A major part...

Issue 2019-05 SYSPRO

Sponsored project on recycling concrete goes into the practical phase

The EU-sponsored project SeRaMCo – “Secondary Raw Materials for Concrete Precast Products” – began on 15 June 2017 with participation of the SySpro founding member, the company Beton-Betz GmbH, as...

Issue 2020-02 Requirements on recycling

Using recycled materials in the concrete products industry in line with applicable standards

Approvals for the new development of raw materials operations are rarely, if at all, obtained, and difficult and lengthy approval procedures have to be allowed for the extension of existing...

Issue 2016-02 Recycling of lightweight concrete

Sustainability benefits of lightweight concrete

The ongoing discussion on closed-loop recycling is increasingly focusing on the construction industry which uses significant amounts of mineral resources and counts among the large waste producers. In...

Issue 2013-02 Lightweight concrete

Lightweight aggregates – a new thermally bound lightweight aggregate of high resource efficiency

Recycling materials from building construction can currently not be adequately recycled. Reasons for this are their considerable heterogeneity in terms of materials composition and high fine particle...