Reconstructing the El Castro Viaduct: How Leca® LWA Delivered Stability and Speed
In June 2022, Spain faced one of its most challenging infrastructure failures: the collapse of the El Castro Viaduct on the A-6 motorway, a critical transport link for more than 18,000 vehicles each day. The collapse created an urgent need for safe, fast, and reliable reconstruction.
To meet this challenge, engineers relied on Leca® Lightweight Aggregate (LWA)—a material that proved essential in stabilising the complex terrain and enabling rapid rebuilding.
A Reconstruction Challenge in Complex Terrain
The collapse was linked to geotechnical instability: fractured limestone, weathered soils, and groundwater infiltration. These conditions made reconstruction difficult, with risks for heavy machinery and piling equipment on unstable slopes.
The solution required creating stable working platforms to allow the safe installation of deep foundations for two new independent viaducts.
Why Leca® LWA Was Key to Reconstruction
Over 8,000 m³ of Leca® LWA was used to create stepped working platforms for piling and foundation works. This lightweight and porous material offered critical advantages:
- Load reduction – At only ~400 kg/m³, Leca® LWA minimised pressure on unstable slopes.
- Effective drainage – Its porous structure dissipated groundwater, reducing pore pressure.
- Stability and safety – Provided a reliable base for heavy machinery in steep, constrained areas.
- Fast installation – Easy handling and compaction allowed tight project deadlines to be met.
- Lower carbon footprint – Manufactured with renewable biomass, Leca® LWA contributed to more sustainable construction.
Logistics That Supported Reconstruction Success
One of the biggest challenges was ensuring a continuous supply of lightweight aggregate. With access restrictions on site, deliveries were staged via temporary stockpiling areas on the decommissioned carriageway. At peak times, up to 12 truckloads per day were coordinated to keep progress steady—demonstrating how efficient logistics combined with the right material choice can make or break a critical infrastructure project.
Building Resilience Through Reconstruction
The El Castro Viaduct reconstruction is more than a story of emergency repair—it’s an example of how innovative materials like Leca® LWA are transforming modern civil engineering.
By enabling stability in geotechnically difficult terrain, supporting sustainable practices, and accelerating construction timelines, Leca® Lightweight Aggregate proved to be the smart fill solution for one of Spain’s most demanding infrastructure challenges.
Looking Ahead
As infrastructure projects across Europe face increasingly complex conditions—whether from geology, climate change, or tight deadlines—Leca® LWA is playing a critical role in delivering safe, sustainable, and resilient solutions.
The El Castro Viaduct stands as a powerful example of how the right material choice can ensure not only reconstruction but also long-term reliability and reduced environmental impact.
👉 Read more about innovative infrastructure projects in the latest edition of BUILD Magazine.
