High performance geotextiles stabilize floodplain platform in Portugal

Overview

A leading real estate investment trust in Spain initiated a new development project in Castanheira do Ribatejo, a flood-prone area near Lisbon, Portugal. The aim of the project was to prepare a reinforced platform above soft alluvial soils using gravel columns, a solution commonly employed to improve load-bearing capacity in complex geotechnical environments. The challenge was to define and implement a reinforcement layer using a geosynthetic that could deliver high tensile strength in both directions, mitigate differential settlements, and support long-term stability.

With a tight construction schedule and growing demand across Europe, the Middle East and Africa, the selection of the right geosynthetic reinforcement solution was critical to meeting both performance requirements and supply deadlines. Solmax was selected to deliver the reinforcement geotextile solution.

This project represented not only a technical endeavor but also an opportunity to implement sustainable construction practices. By minimizing the use of granular materials and reducing construction time, the deployment of advanced geosynthetics such as MIRAFI^® Geolon PET 200 S contributed to both environmental benefits and cost-efficiency.

Challenge

The primary technical challenge in this project was the presence of highly variable and complex alluvial deposits beneath the construction site. These soft soils required thorough geotechnical characterization and presented a high risk of differential settlement under loading. A traditional foundation approach would have been both time-consuming and resource-intensive, requiring large quantities of aggregate and extensive stabilization measures.

To address these conditions, a platform reinforced with high-modulus biaxial geotextiles was proposed. The reinforcement needed to function reliably over time, with minimal deformation under stress, and provide sufficient tensile strength in both directions to distribute loads evenly over the gravel column matrix. The importance of controlling settlement behavior while maintaining installation efficiency led to a preference for a geosynthetic solution with well-documented mechanical and durability properties.

A second layer of complexity was the project’s demanding timeframe. Summer is a peak construction season across Europe and the Middle East, placing significant pressure on product availability and delivery timelines. Supplying a large volume of specialized woven geotextile within a short window required precise coordination between Solmax’s manufacturing and the local distributor, and the construction team in Portugal.

The installation method required a 50 cm overlap between adjacent rolls of the biaxial woven geotextile, laid directly atop the prepared natural soil surface. Ensuring a consistent and efficient installation process despite the challenging terrain and tight timeline was essential to prevent delays or misalignment in the reinforcement layer.

What further distinguished this project was the extensive analysis needed to determine the long-term design strength of the geotextile. Accurate reduction factors for creep, installation damage, and chemical/biological degradation had to be considered to ensure the long-term stability of the platform.

Solution

To meet the performance and logistical demands of the project, Solmax supplied MIRAFI Geolon PET 200 S – an engineered biaxial woven geotextile made from high-modulus polyester fibers. This material was specifically selected due to its high stiffness in both machine and cross directions and long-term durability. With a robust CE certification and a track record of use in similar site development projects in the same region, MIRAFI Geolon PET 200 S was considered the most reliable solution.

Production was ramped up at Solmax’s Netherlands facility, with additional shifts scheduled to ensure timely manufacturing. Partial shipments were coordinated and dispatched rapidly, allowing the contractor to maintain continuous progress without interruption. This flexible approach to production and logistics ensured that all phases of the platform installation aligned with the construction schedule, mitigating potential delays during the high-demand season.

The use of MIRAFI Geolon PET 200 S provided multiple advantages. From a performance perspective, the geotextile reduced vertical and lateral deformation, and improved load distribution. These characteristics were essential for the anticipated building loads and ensured the platform’s performance over its design life. Additionally, by reinforcing the platform with geosynthetics, the required thickness of granular fill could be reduced, leading to material savings, reduced truck movements, and overall lower environmental impact.

Alternative geotextile solutions were evaluated during the design phase. However, based on previous success in the area and the confidence of the engineering team, MIRAFI Geolon PET 200 S was chosen for its balance of technical performance, ease of installation, and supply reliability.

From a broader perspective, this project reinforced the critical importance of pairing geotechnical expertise with high-quality geosynthetics. While design calculations provide the framework for project success, the on-the-ground experience of the engineers – particularly in complex soil environments – was instrumental in guiding product selection and installation methodology. In cases where the design approach evolves due to unforeseen soil behavior, the knowledge and support of Solmax’s technical team serve as a dependable resource.

This project was completed on time and met all technical performance benchmarks. The high quality of the woven polyester geotextile and the responsiveness of the supply chain contributed to a seamless installation process, allowing construction to proceed without delay. As a result, both the client and the engineering firm expressed strong satisfaction with the outcome. The successful implementation of MIRAFI Geolon PET 200 S in this project has already led to ongoing opportunities in similar developments throughout the Lisbon area.

This case study demonstrates how geosynthetics – when combined with deep geotechnical expertise and responsive project management – can deliver reliable, sustainable outcomes in even the most challenging soil conditions.