Re-use of waste bricks as substrate for land-fill coverage and tree plantings


Brick granulate is growth-inducing due to its good storage capacity and controlled release of water. Moreover, waste bricks improve soil stability. The positive features of bricks are not realised as they are normally re-used as bulk material after demolition of buildings. In 2014, 55 million tons of rubble, including bricks, were produced in Germany.

For re-cultivation layers of land fills, plenty of substrate is needed. This substrate is subjected to high requirements because in the long term the re-cultivation layer with its vegetation has to protect the underlying technical layers. For enterprises, it is difficult to comply with the German quality standard 7-1 for re-cultivation layers (BQS 7-1) as long as there is no standardized system solution. A combination of a substrate with bricks and an appropriate vegetation could become the required system solution. Furthermore, this substrate would use the potential of brick waste better than the use as bulk material. Such a substrate would also be favourable for urban tree plantings as here substrates with high water storage capacity and robust mechanical qualities are needed.

The aim of the project is to re-use brick waste as innovative planting substrate. Such substrate should improve water and nutrient storing by adding brick rubble. A greenhouse experiment will investigate the effect of brick addition on grasslands as well as trees saplings. Experimental plants are species of oatgrass meadows and the trees Acer platanoides and Tilia cordata. The experiment should reveal which physico-chemical treatment of bricks is most effective, and how high the ratio of bricks to soil should be. Moreover, additives like mycorrhiza and different moisture regimes will be tested. The following questions will be answered:

  1. Which seed mixture is appropriate to grow on plant substrate with bricks?
  2. Do wild seeds meet the requirements of the German quality standard 7-1 (BQS 7-1) better than cultivar seeds?
  3. Which physico-chemical treatments of bricks and which additives are best for growth and survival of herbs and trees?
  4. How much bricks should be added to the substrate?
  5. Which interactions are there between brick percentage and watering regime?

The project is sponsored by the Zentrale Innovationsprogramm Mittelstand (ZIM). This funding programme of the Federal Ministry of Economics (BMWi) supports co-operations between medium-sized enterprises and research institutes to develop innovative products. The project is carried out in co-operation with the brickyard Leipfinger-Bader and the landscaping and recycling enterprise Wurzer Umwelt.

More information can be found at the page of the Chair for Restoration Ecology, TUM.



Prof. Dr. Johannes Kollmann

Chair for Restoration Ecology

Technical University of Munich

jkollmann[at] M.Sc.


Markus Bauer

Chair for Restoration Ecology

Technical University of Munich



Project Duration