Strategies for a More Sustainable Management of Existing Concrete Structures

Cement production is responsible for about 8% of carbon dioxide emissions worldwide. Reducing the use of traditional reinforced concrete is essential to minimize the negative environmental impact on the construction sector. In central urban areas, existing structures that do not correspond to actual architectural standards or that have insufficient structural capacities are often just replaced. A more sustainable management of existing concrete structures requires strengthening, refurbishing, or reusing rather than replacing. In other words, the use of existing concrete structures must be extended to build less. In this article, a global approach involving three strategies is proposed to achieve this goal. The first strategy involves accurately assessing structural safety through structural performance monitoring. With this strategy, untapped reserves of capacity are often found, avoiding unnecessary replacement. In the second strategy, concrete structures are strengthened by using ultra-high performance fiber-reinforced cementitious composite. This cementitious material has important tensile and compressive strength and remains waterproof under service conditions, enabling the rehabilitation of existing deficient concrete structures. Finally, when deconstruction cannot be avoided, concrete elements can be reused in new structural systems. Reusing rather than recycling enables the drastic reduction of the environmental impacts of new construction. For each strategy, examples of full-scale applications will be provided where the environmental benefits are highlighted.