No abstract

As the most widely used construction material worldwide, concrete is the main cause of greenhouse gas emissions, material depletion, and waste generation by the construction industry. Typically, concrete waste is crushed and, at best, reclaimed into recycled aggregate or used as gravel. This process is energy-intensive and results in a reduction in material properties. In contrast, the direct reuse of concrete elements from obsolete structures offers great potential for significantly reducing the environmental impact of new constructions. To be reused, concrete elements are carefully sawn out of soon-to-be-demolished buildings. Elements are then used without other major transformations for another service cycle in a new assembly. This paper analyses two recent projects in Switzerland that showcase innovative applications of concrete reuse: a post-tensioned segmented arch footbridge and a parking pavement. Both projects reuse blocks extracted from cast-in-place concrete buildings undergoing transformation or demolition. In this paper, environmental and economic analyses provide a comprehensive understanding of the alleviations and costs involved. Results are compared to those of alternatives with conventional construction methods. The two projects reusing concrete globally showcase a drastically lower environmental impacts for comparable or higher construction costs, hence calling for future developments of such new circular construction strategies.

The production of concrete, the most widely used construction material, detrimentally affects the environment. Obsolete reinforced concrete (RC) load-bearing structures, even when still in good condition, are today prematurely crushed and landfilled or recycled into new concrete mixes. Little known and rarely implemented, the reuse of RC structural components is an alternative strategy towards more circularity in the construction industry. Since 2021, RC component reuse has been implemented in a series of construction and deconstruction projects in Switzerland.This paper identifies existing process sequences for RC-reuse projects and proposes one that involves a new assessment procedure to evaluate the reusability of the components early on and facilitate their future reuse planning. The paper discusses the application of this procedure to three deconstruction projects. Results are encouraging with regard to the durability of RC components. Almost 90% of the RC components of a building could be reused for new purposes with the same stability and exposure as in the donor building.

Concrete accounts for the largest share of worldwide building material use and waste generation, with cement production being responsible for approximately 9% of global anthropogenic CO 2 emissions. A currently untapped strategy to significantly reduce these environmental impacts consists in reusing reinforced concrete (RC) elements in new load-bearing applications. This paper presents a new design-and-build concept to reuse cast-in-place RC wall and slab elements sourced from obsolete buildings. The applicability of the proposed paradigm is demonstrated through a prototype: a 10-m spanning post-tensioned segmental arch made of 25 reclaimed concrete blocks. The paper illustrates the complete workflow, including the sourcing of the blocks through sawing and the prototype assembly. A comparative Life Cycle Assessment shows that the prototype structure has a significantly lower environmental impact than equivalent designs made of new material.