Not least among the goals pursued by producing concrete components and buildings is social sustainability. This includes the share of home ownership and the establishment of habitation suitable for various age groups, household sizes and income groups. The provision of state-of-the-art office space and production sites meets the changing requirements of today’s work processes. Modular construction systems and the use of prefabricated concrete components rationalise building work and increase the quality of buildings. Examples of projects are presented in the Federal German Cement Industry Association’s Systembaustudie (prefabricated buildings study). The study makes it evident that prefabrication and individuality of constructed environments do not constitute a contradiction. The growing need for mobility requires further investment in the transport infrastructure. In addition to the traditional requirements of performance and longevity for new construction and expansion of traffic routes, safety and environmental compatibility are becoming ever more important criteria for sustainable mobility. High-absorption noise protection barriers, passive safety features and concrete road paving contribute to meeting these requirements.
Providing complete fractionation, concrete can recycled to 100 percent. Concrete recycling divides into recycling of unset concrete and set concrete. Unset concrete recycling refers to the internal circulation within the concrete works. Return quantities – concrete obtained from mixer and pump cleaning – and unused concrete returned to the plants in truck mixers are separated and reintroduced to production. These return quantities constitute approximately 2.5 percent of a concrete works’ production. The recycled water and the particles contained in the waste concrete are used instead of fresh water and primary aggregates. The use of recycled water, waste concrete and waste mortar for concrete production is regulated in a directive published by the German Committee for Reinforced Concrete (DAfStb).
When recycling set concrete, the broken concrete is treated, i.e. broken down and sieved so that coarse and fine recycled aggregates are produced. Use of pure, high-quality recycled aggregates as an additive for concrete up to strength class C 30/37 is regulated in another of the DAfStb’s directives. For set concrete recycling, employment of cement as a binder is indispensable. Cement further facilitates the utilisation of other mineral construction industry waste, e.g. to manufacture masonry units from slate chippings. Thanks to persistent efforts in the field of construction material recycling, the year 2004 saw more than 61.6 percent of the produced building rubble and more than 93 percent of the rubble from road demolition introduced to recycling. The European targets for the recycling rate are in Germany thus already being met today. To promote construction material recycling, the consortium Kreislaufwirtschaftsträger Bau (construction industry recycling agency) was founded in 1996. The cement industry is associated with this agency through its membership in the German Building Materials Association.