Dando una segunda vida. Estrategias de reciclaje en la construcción

Construction and demolition waste (CDW) recycling has undergone rapid regulatory advancement in the European Union over the past decade. The Waste Framework Directive 2008/98/EC set a target of 70% recovery by weight of non-hazardous CDW by 2020, a goal met by the EU-27 average at 71% according to Eurostat (2023). Disparities between countries are notable: the Netherlands (99%), Denmark (96%), and Germany (91%) lead in recycling, while Spain (75%), Portugal (62%), and Greece (48%) occupy intermediate or lagging positions. The EU's new Circular Economy Action Plan (2020) and the proposed Construction Products Regulation (2022) establish minimum recycled content requirements for construction materials, with targets of 15-30% for concrete and 25% for steel from 2030.

In Spain, Royal Decree 105/2008 regulates CDW management and mandates on-site waste separation into fractions of concrete, bricks, metals, wood, glass, and plastics when the volume exceeds 80 m³. Annual CDW production in Spain is estimated at 37 million tonnes according to the National Waste Management Framework Plan (PEMAR 2016-2022), of which 75% is handled at authorized facilities. The country has 487 CDW treatment plants with an installed capacity of 52 million tonnes per year according to data from GERD (Asociación Española de Gestores de Residuos de Construcción y Demolición, 2023), although the average utilization rate of these facilities is only 42%, indicating significant room for growth.

Recycled aggregate derived from crushing demolished concrete is the highest-volume product in CDW recycling. The standard EN 12620:2002+A1:2008 and its complement EN 206:2013+A2:2021 allow substitution of up to 50% of natural coarse aggregate with recycled concrete aggregate in concretes up to strength class C30/37, provided that the sulfate content is below 0.8% and water absorption does not exceed 7%. In Spain, EHE-08 (the Structural Concrete Code) limits substitution to 20% for structural concrete and 100% for non-structural mass concrete, with an impurity content (wood, glass, plastic) below 1%.

The cost of recycled aggregate ranges from 4 to 8 euros per tonne at the plant, compared with 6.5 to 12 euros per tonne for natural quarried aggregate, representing a saving of 25-40% on raw material costs according to data from ANEFA (Asociación Nacional de Fabricantes de Áridos, 2023). The SeRaMCo (Secondary Raw Materials for Concrete Precast Products) project, funded by Interreg NWE with 6.3 million euros, demonstrated that precast concrete products with 100% recycled aggregate achieve strengths of 40-50 MPa, suitable for structural applications. The Heidelberg Materials plant in Lixhe (Belgium) processes 250,000 tonnes per year of demolished concrete, producing certified recycled aggregate used in precast concrete manufacture with 30% natural aggregate substitution and a 12% reduction in emissions per cubic meter.

Reclaimed wood from demolitions and refurbishments achieves recycling rates of 38% in the EU according to Eurostat (2022), with end uses ranging from particleboard manufacture (55% of recycled wood) to energy recovery in biomass plants (35%) and direct reuse in construction (10%). Recycled particleboard uses up to 100% post-consumer wood, with plants such as the Kronospan facility in Burgos processing 400,000 tonnes per year of reclaimed wood. Direct reuse of solid timber beams and planks requires grading per EN 14081-1:2016 using machine strength grading equipment that measures dynamic modulus of elasticity, allowing strength classes (C18, C24, C30) to be assigned to reclaimed pieces over 50 years old.

Recycled steel represents a well-established success story: 85% of structural steel worldwide is manufactured with a recycled content ranging from 25% (basic oxygen furnace, BOF) to 97% (electric arc furnace, EAF), according to the World Steel Association (2023). Steel production via EAF consumes 400 kWh per tonne, compared with 5,000-6,000 kWh per tonne for the primary route from iron ore, representing an emissions reduction of 58-75%. In the EU, the recycling rate for construction steel reaches 92%, with an annual output of 85 million tonnes of recycled steel. Recycled aluminium, used in window frames and facades, consumes only 5% of the energy required for primary production (0.7 MWh per tonne versus 14 MWh per tonne), with recycling rates of 96% in the European construction sector according to the European Aluminium Association (2023).

The circular economy in construction has given rise to innovative business models that connect the supply of reclaimed materials with demand from new projects. The Madaster platform, founded in the Netherlands in 2017, functions as a digital materials cadastre that records the composition and residual value of a building's components, with over 5,000 registered buildings and 220 million tonnes of catalogued materials in 2023. Rotor Deconstruction, based in Brussels, has operated since 2012 as a company specializing in selective deconstruction and resale of materials, managing more than 3,000 tonnes per year of reclaimed materials (flooring, joinery, sanitary ware, lighting) at prices 30-70% below the equivalent new material.

In Spain, the Recover platform connects CDW generators with treatment plants and buyers of recycled materials, managing over 500,000 tonnes per year in transactions. The deposit guarantee model applied in Belgium requires a deposit of 15 to 30 euros per tonne of material used on site, an amount recovered upon demonstrating proper waste management at end of life. This system has raised the CDW recycling rate in Flanders to 97%, the highest in Europe. The EU Construction & Demolition Waste Management Protocol (2018) establishes a voluntary framework for pre-demolition audits that identifies recoverable materials, with an average cost of 0.50 to 1.50 euros/m² of built floor area and an estimated return of 3 to 8 euros/m² in recovered material value.