Seabed erosion (scour) around monopile or jacket foundations can undermine stability if not controlled. Scour protection and repair grouting stabilizes these eroded areas by filling voids and forming a dense protective layer around the base. The operation is carried out underwater in dynamic flow conditions, requiring a grout that resists washout, gains strength quickly, and bonds securely to steel or concrete.

Key Grout Performance Requirements:

• Excellent anti-washout performance in strong currents.

• High compressive strength (≥70 MPa) and abrasion resistance.

• Rapid setting and early strength for quick stabilization.

• High injectability and penetration for irregular cavities.

• Non-shrink stability to prevent new voids.

• Long-term resistance to seawater and chemical attack.

ZRETE Solution:
CBGM-70 Underwater Grout is designed for scour repair operations. It exhibits superior anti-dispersion (<1.5% washout loss) and can be pumped directly into seawater. The grout develops over 20 MPa in one day and more than 70 MPa after 28 days, ensuring rapid stabilization. Its dense, impermeable matrix forms a rock-like armor layer around the foundation, preventing further seabed erosion and extending the service life of offshore wind structures.

Suction bucket foundations are steel caissons installed by suction into the seabed. After installation, the bucket’s internal cavity or buoyancy chamber is filled with grout to add structural stiffness and mass. Grouting such large volumes underwater presents unique challenges: displacement of seawater, prevention of washout, and weight control to avoid overloading the foundation.

Key Grout Performance Requirements:

• Lightweight density to minimize added foundation weight.

• High flowability for complete cavity filling around internal stiffeners.

• Extended open time for continuous pumping.

• Shrinkage-compensated or expansive curing to prevent voids.

• Anti-washout formulation to displace seawater without segregation.

• Adequate compressive strength (~40–60 MPa) for structural stability.

ZRETE Solution:
CBGM-5 Low-Density Grout is engineered for suction bucket applications. It combines high flowability with lightweight composition, reducing overall foundation mass while achieving full cavity fill. Its extended workability enables continuous pumping, and its controlled expansion ensures a tight bond to internal surfaces. CBGM-5’s anti-washout additives allow placement directly into seawater, providing a homogenous fill and long-term stability within the bucket foundation.

Gravity base foundations rely on complete contact between the base slab and seabed. Uneven seabed surfaces create voids that must be filled with underwater grout to achieve uniform load distribution. Underbase grouting ensures full bearing support and prevents long-term settlement. The grouting operation occurs underwater and requires a highly flowable, stable material that can be pumped across large areas beneath the foundation without washout.

Key Grout Performance Requirements:

• High flowability and extended workability for large-area placement.

• Anti-washout stability for underwater application (dispersion loss <2%).

• Shrinkage compensation or controlled expansion to ensure full contact.

• Compressive strength of 70–100 MPa for long-term bearing capacity.

• Early strength development (>20 MPa in 1 day) for early structural stability.

• Durability against sulfate, chloride, and thermal cycling in marine conditions.

ZRETE Solution:
CBGM-70 Underwater Grout is specifically formulated for underwater void filling. It delivers 70 MPa compressive strength, zero bleeding, and minimal washout. The grout maintains flowability for up to 60 minutes, with a spread ≥290 mm initially. Controlled expansion ensures intimate contact with both the gravity base and seabed. CBGM-70’s low permeability and corrosion-free composition make it ideal for long-term support beneath offshore gravity foundations.

Jacket foundations for offshore turbines transfer loads through grouted pile sleeves connecting each leg to the driven pile. These annuli are narrower and often located below water level, demanding grouts that can be placed underwater without segregation or washout. The grout must fill complex geometries with shear keys and maintain bond integrity under extreme cyclic loads.

Key Grout Performance Requirements:

• High compressive and shear strength (≥100 MPa).

• Excellent underwater pumpability and anti-dispersion stability.

• Rapid early strength gain for faster jacket installation.

• Non-shrink expansion to maintain preload and eliminate voids.

• Fatigue and crack resistance under cyclic wave and wind loads.

• Chemical and corrosion resistance for long-term marine exposure.

ZRETE Solution:
CBGM-125 is optimized for jacket sleeve applications, offering 125 MPa compressive strength, high flowability, and self-compacting characteristics. It hardens with slight expansion, locking into shear keys to ensure secure fixation. For fully submerged placement, CBGM-70 Marine-Grade Grout provides superior anti-washout performance and develops 70 MPa strength at 28 days, delivering reliable underwater curing and early strength even in cold seawater.

Solution Content:
Offshore wind monopile foundations use a transition piece fitted over the monopile, forming an annular gap that must be grouted to create a solid structural connection. This grouted annulus faces intense dynamic loads from wind turbine operation and crashing waves, leading to cyclic bending and shear stresses over millions of cycles. The marine environment adds challenges: saltwater exposure, potential seawater ingress during grouting, and temperature fluctuations that demand a durable grout resistant to corrosion and thermal cycling.

Key Grout Performance Requirements:

• Ultra-high compressive strength exceeding 100 MPa for secure load transfer.

• Fatigue and dynamic load resistance to endure millions of load cycles.

• Volume stability (non-shrink or slightly expansive) to maintain tight contact.

• Anti-washout behavior for placement in wet or partially submerged annuli.

• High early strength for rapid installation progress.

• Long-term durability and corrosion resistance in saltwater conditions.

ZRETE Solution:
CBGM-125 Ultra High-Strength Grout provides compressive strength above 125 MPa at 28 days while maintaining shrinkage compensation. Its nano-fiber reinforcement ensures fatigue resistance and crack control. The grout remains cohesive in wet conditions and exhibits controlled expansion to maintain contact with steel surfaces. CBGM-125 is chloride-free, low-permeability, and designed for marine durability, ensuring long service life of monopile–transition piece connections.