The Porto Metro continues to expand with several strategic extensions designed to improve urban mobility in the Portuguese metropolis. This major infrastructure project is utilizing next-generation tunnel boring machines to address challenges related to transportation, traffic flow, and environmental transition. In this type of underground operation, managing drilling mud and excavated materials presents a major technical and logistical challenge to ensure that deadlines are met and site safety is maintained.
Challenges Encountered at the Porto Metro Construction Site
As part of the extension of the Porto metro line, more than 12,000 m³ of liquid drilling mud has been treated with APROMUD® over the past two months. On this large-scale tunnel boring machine (TBM) project, the teams had to deal with several operational challenges related to the management of mud and TBM spoil.
The mineral slurry from drilling operations had a high water content, making its handling, loading, and transport particularly complex. The disposal rates required by the project called for a solution capable of ensuring rapid and reliable slurry dewatering to prevent any slowdown in production.
Added to this were significant logistical constraints: optimizing truck rotations, minimizing runoff onto roadways, securing the dumpsters, and strictly adhering to project deadlines. In a context where every hour counts, poor slurry management can quickly become a bottleneck for the entire project.
APROMUD®: An Innovative Solution for Sludge Dehydration
To address these challenges, the teams selected APROMUD®, the super-dehydrating agent developed by APROTEK for the treatment of drilling mud, sediments, and excavated materials with high water content.
Unlike traditional solutions based on lime or mineral binders, APROMUD® acts immediately upon contact with water thanks to superabsorbent polymer technology. This ultra-fast absorption capacity transforms liquid sludge into manageable and transportable materials in just a few minutes.
The product also stands out for its very low dosage, ease of application, and excellent compatibility with waste recovery processes. Thanks to its effectiveness, underground construction companies can maintain tunnel boring machine production rates while reducing the overall environmental impact of the project.
Focus: Superabsorbent Polymers, a Disruptive Technology
The superabsorbent polymers used in APROMUD® have an exceptional ability to capture and retain large amounts of water. Upon contact with drilling mud, they instantly absorb moisture and alter the physical structure of the excavated material to create a stable, cohesive substance.
This technology offers several major advantages for tunnel boring and drilling sites:
- rapid and immediate action on liquid slurry
- drastic reduction in waiting times before removal
- low dosage required to achieve effective results
- no exothermic reaction
- inert, pH-neutral product
- compatibility with waste recovery processes
Derived 100% from low-carbon recycling sources, APROMUD® is fully aligned with the new environmental requirements for major infrastructure projects.
Product Application on Site
Application
After determining the volume and the amount of product required, APROMUD® was applied directly from the bucket to the liquid slurry in the spoil pit. This quick and simple method allows for immediate integration into site processes without major changes to existing operations.
Mixing and Activation of the Product
Once the product was applied, the excavator operator mixed APROMUD® with the slurry. The product reacts upon contact with water, hence the importance of homogeneous incorporation into the mineral slurry.
After mixing, the product acts quickly and takes about fifteen minutes to reach its optimal effectiveness. The excavated materials then achieve a stable consistency, allowing for their safe handling and removal.
Removal of excavated materials
Once the desired result is achieved, the dried slurry becomes immediately transportable. The removal of tunnel boring machine spoil can then be carried out smoothly, safely, and in compliance with site requirements.
The risk of spillage in dump trucks is significantly reduced, as is runoff onto the roadway near the site. This operational improvement directly contributes to the overall safety of the construction site and nearby residents.
Immediate benefits for tunnel boring machine sites
Safety
APROMUD® is a 100% inert, pH-neutral product that is safe for operators. It is non-powdery and does not undergo exothermic reactions, posing no risk of burns or dust emissions when used on-site.
Optimized dosage and rapid results
The product’s effectiveness allows for extremely low dosages. At the Porto metro site, a dosage of between 0.2% and 1% was sufficient—equivalent to just 2 to 12 kg per m³ of slurry.
The final volume of the slurry thus remains virtually unchanged, unlike traditional solutions that significantly increase the volume of material to be disposed of. After mixing, it takes only fifteen minutes to achieve a usable result, whereas mineral binders often require several hours.
Easier transport and disposal
Once treated, the excavated materials can be loaded optimally into dump trucks to maximize transport capacity. Truck trips are streamlined, and transport is safe, with no dripping or loss of material on public roads.
Thanks to this logistical optimization, the Porto metro construction site achieved:
- 10% fewer truck trips
- 3,500 km of road transport avoided
- 4.5 tons of CO₂ emissions avoided
Meeting Production Rates and Construction Deadlines
By ensuring efficient and immediate slurry management, APROMUD® helps maintain the removal rates required by tunnel boring machines and prevents logistical bottlenecks.
The job site remains clean, safe, and operational, even under intensive production conditions. This responsiveness is a major advantage for underground construction companies facing particularly demanding project deadlines.
A solution with a low environmental footprint
Beyond its operational performance, APROMUD® actively contributes to reducing the carbon footprint of construction sites.
Derived from low-carbon recycling processes, compatible with existing disposal methods, and without altering the initial chemical structure of the excavated material, the product offers a sustainable alternative to conventional sludge dewatering solutions. Furthermore, the solution has been certified as an “Efficient Solution” by the Solar Impulse Foundation, a testament to its technical performance, economic efficiency, and environmental friendliness.
On tunnel boring and drilling sites, this approach balances on-site efficiency, crew safety, and reduced environmental impact.
APROMUD®: The New Standard for Drilling Mud and Tunnel Boring Machine Cuttings
The Porto Metro project perfectly illustrates APROMUD®’s ability to address modern slurry management challenges on large-scale underground infrastructure projects.
Fast, safe, low-carbon, and extremely effective, the product provides a concrete solution to the operational challenges faced by public works and tunnel boring companies.
Would you like to test APROMUD® on your site or discuss your sludge dewatering and excavated material management challenges? The APROTEK teams are here to help you identify the solution best suited to your on-site requirements.
