Fractured rock masses below the water table are a problem in underground excavations because of their low strength and high permeability. Nowadays, these negative connotations can be reduced with techniques such as injection of cement, microcement, or resins grouts. These materials increase the rock mass cohesion while reducing the flow of water through the discontinuities. This paper describes the work carried out to design a waterproofing screen for a three-storey underground basement located in a building near the Bilbao estuary (Northern Spain) and with problems of water seepage from the river. First, a survey of the rock mass is carried out. This survey shows the presence of highly fractured zones and the variability of the permeability as functions of the fractures. Subsequently, the effect on permeability caused by the injection of cement grouts and microcement is studied by means of two pilot injection boreholes and eight control boreholes. Finally, a behavioural model is proposed to explain the heterogeneity observed in the radius of influence of the injection. As a result, a waterproofing screen with three types of treatment is designed: An ordinary treatment with cement grouts, an intensive treatment with microcement grouts, and an isolation treatment with cement-bentonite grouts.

One year on from the outbreak of the global COVID-19 pandemic, EU policies have defined recovery instruments that enhance the transition towards a more circular economy, making European industries more sustainable, resilient, digital and innovative. The underground work industry is no exception and must crystallise the trends in innovation that have been developing in recent years, which will undoubtedly contribute to achieving better safety and efficiency parameters in tunnel construction, with the economic impact that this means. This work shows different innovation strategies along the design and construction of the Arnotegi tunnel, as part of the extension works of the Bilbao South Metropolitan Bypass. These strategies have been the implementation of the BIM methodology in the underground works, the use of environmental sensors and the optimisation of the shotcrete placement and the positioning of machinery inside the tunnel. The implementation of these strategies has allowed improved collaboration between agents and a time saving of 6.60% with respect to the initially planned deadline.

El presente artículo describe las obras de estabilización de la antigua cantera de Punta Lucero en las instalaciones de la Autoridad Portuaria de Bilbao. Estas obras han sido necesarias para acabar con la caída ocasional de piedras y bloques que amenazaban diversas instalaciones con depósitos de combustibles implantadas en la plataforma portuaria. La actuación se ha concebido considerando la oportunidad de aprovechar los materiales para un proyecto en sus proximidades, las obras del Proyecto de Espigón Central de la ampliación del Puerto de Bilbao. Por otra parte, la operación de excavación se ha organizado mediante banqueo descendente y el transporte ha sido realizado a través de pozo-túnel. Este método presenta múltiples ventajas, tanto desde el punto de vista de la seguridad como desde la perspectiva ambiental y de emisión de gases de efecto invernadero. El empleo de este sistema no tiene precedentes en obras de estabilización de laderas.

The Urdinbide road tunnel goes through the Autzagane aquifer. This important aquifer is located within the hydrogeological area of the Urdaibai Biosphere Reserve, one of the most important biosphere reserves in the Iberian Peninsula, and it is also used as a source of drinking water for some urban areas in the municipality of Amorebieta-Etxano. The construction of the tunnel could pose a potential risk to the normal functioning of the aquifer, so its design included a special procedure for injecting cement and microcement to waterproof the surrounding area of the drilling, preventing the tunnel from functioning as a drain for the aquifer. The project initially included an intensive hydrogeological characterization of the rock massif, as well as a monitoring phase during the construction works, which allowed a real-time verification of the influence of the tunnel construction on the functioning of the aquifer and the restoration of its normal functioning once the works were completed. The work carried out has shown that the construction of the tunnel has not caused a significant impact on the Autzagane aquifer.

La ciudad de Bilbao ha vivido un proceso modélico de transformación urbana en los últimos años, convirtiéndose en una urbe cosmopolita y de diseño. El proyecto de Zorrotzaurre es la última operación de regeneración urbana de la ciudad. El objetivo principal es convertir un espacio actualmente degradado en un nuevo barrio de Bilbao, buscando una nueva visión del modelo de ciudad. El proyecto ha sido concebido empleando como eje vertebrador la sostenibilidad e influenciado por el impulso a la economía circular. En la presente nota técnica se describe el uso de áridos reciclados y siderúrgicos en los firmes y pavimentos de la nueva urbanización de la margen derecha de Zorrotzaurre, lo cual se considera esencial en el diseño de infraestructuras urbanas sostenibles Bilbao has experienced a model process of urban transformation in recent years, becoming a cosmopolitan and design city. The Zorrotzaurre project is the last operation of urban regeneration of the city. The main objective is to convert a currently degraded space into a new neighbourhood in Bilbao, seeking a new vision of the city model. The project has been conceived using sustainability as its backbone and influenced by the impulse of the circular economy. This technical note describes the use of recycled and steel aggregates in the pavements of the new urbanization of the right bank of Zorrotzaurre, which is considered essential in the design of sustainable urban infrastructures

Stone Mastic Asphalt (SMA) mixtures are widely used in high-capacity road pavements due to their durability and resistance to permanent deformation. However, although electric arc furnace (EAF) steel slag and recycled crumb rubber have been individually investigated as alternative materials in asphalt mixtures, evidence regarding their simultaneous incorporation in SMA mixtures under full-scale construction and real traffic conditions remains limited. Moreover, quantitative environmental assessments are often restricted to simplified or qualitative approaches, with limited reporting of carbon footprint results. This study investigates the combined use of electric arc furnace (EAF) steel slag aggregates and recycled crumb rubber in SMA mixtures, integrating laboratory evaluation with full-scale field application on a high-traffic motorway. Two SMA 11 mixtures were designed and assessed: one incorporating steel slag aggregates as a replacement for natural coarse aggregates, and another combining steel slag aggregates with recycled crumb rubber added through the dry process (0.8% by mixture mass). Laboratory testing included volumetric characterization, moisture sensitivity and rutting resistance, while field validation covered surface macrotexture, skid resistance, executed thickness and interlayer bonding. Both mixtures fully complied with the applicable technical specifications, achieving indirect tensile strength ratios (ITSR) above 90% and wheel-tracking slopes below 0.07 mm/10³ cycles. A simplified comparative life-cycle assessment (LCA), limited to modules A1–A3, showed a reduction in CO₂-equivalent emissions of approximately 2% for the mixture containing steel slag and up to 27% for the mixture combining steel slag and recycled crumb rubber, mainly due to the valorization of industrial by-products and end-of-life tyres. Overall, the results demonstrate the technical feasibility and potential environmental benefits of these SMA mixtures within the defined scope of laboratory verification, short-term field performance and screening LCA. The contribution of this study lies in providing applied evidence from a full-scale motorway intervention, complementing predominantly laboratory-based studies and offering a quantified environmental comparison under consistent methodological assumptions.