Conbextra TA: Ultra-High Performance Cementitious Grout for Wind Turbine Foundations

Product Overview

Conbextra TA is a ready-to-use cementitious grout specifically formulated for grouting the structural transition pieces of onshore wind turbine foundations. This ultra-high performance product is engineered to deliver exceptional strength, durability, and reliability in demanding wind turbine foundation applications.

Primary Uses

Conbextra TA is designed exclusively for wind turbine connections, serving as the grouting material for structural transition pieces in onshore wind turbine foundations. The product accommodates gap depths ranging from 50 to 250 millimeters, making it suitable for substantial grouting applications.

Key Advantages

Conbextra TA offers numerous performance benefits that make it ideal for wind turbine foundation work:

• High flexural strength and modulus of elasticity without the addition of fibres, which enhances the flow characteristics of the grout
• Rapid development of strength enabling removal of temporary forms and supports even at low temperatures
• Very high ultimate compressive strength providing long-term structural integrity
• Fatigue resistance ensures durability under the cyclic loading conditions typical of wind turbine operations, with testing conducted to Model Code 1990 and 2010 S-N curves
• Suitable for pumping or pouring over a large range of applications, offering application flexibility
• No segregation or bleeding, ensuring consistent final physical performance and preventing pump blockages
• Unique cement chemistry that controls heat of hydration, enabling both thin and thick sections to be cast
• High workability retention facilitates casting of large sections
• Positive expansion after casting ensures structural completeness

Technical Specifications

General Properties

Property	Specification
Granulometry	0 - 4mm
Gap depth	50 - 250mm*
Application temperatures	2 to 35°C
Exposure classes (EN 2001)	X0, XC4, XD3, XS3, XF3, XA2, WF
Standards compliance	EN1504-6:2006

*For larger gap depths, contact Fosroc Technical Department.

Fresh Wet Properties (@ 0.08 w/p ratio)

Property	Test Method	Result
Final set	EN196-3:1996	<6 hours
Expansion	—	0-1%
Air content	EN 1015-7	≤4%
Slump flow	EN12350-8	>700mm
Flow trough	EN 13395-2	>750mm (Class f3)
Flow retention	—	Minimum 650mm after 30 minutes

Mechanical Properties (@ 0.08 w/p ratio)

Property	Test Method	Result
Static modulus of elasticity	—	40 GPa
Flexural strength	EN196-1:1996	7 N/mm² @ 1 day; 12 N/mm² @ 7 days; 16 N/mm² @ 28 days
Compressive strength	EN 12390-3 (150mm cubes)	60 N/mm² @ 1 day; 85 N/mm² @ 7 days; 115 N/mm² @ 28 days
Compressive strength	EN 12190 (40x40x160mm prisms)	30 N/mm² @ 1 day; 100 N/mm² @ 7 days; 120 N/mm² @ 28 days
Tensile splitting strength	EN 12390-6	≥9 N/mm²
Shrinkage classification	—	SKVM0

Application Instructions

Surface Preparation

Foundation surface: The substrate surface must be free from oil, grease, or any loosely adherent material. If the concrete surface is defective or has laitance, it must be cut back to a sound base. Bolt holes or fixing pockets must be blown clean of any dirt or debris.

Pre-soaking: Several hours prior to grouting, the cleaned foundation area should be flooded with fresh water. Immediately before grouting, any free water should be removed, with special attention paid to bolt holes and fixing pockets.

Formwork

The formwork must be constructed to be leakproof, as Conbextra TA is a free-flowing grout. This is achieved by sealing all joints very well. In some cases, a mortar formwork is practical. The formwork should include outlets for pre-soaking water.

Mixing

For optimal results, a mechanically powered grout mixer is essential. For quantities up to 50 kg, a slow-speed mixer fitted with a high-shear paddle is suitable; larger quantities require a high-shear vane mixer.

Mixing procedure:

• Place the required quantity of clean water (maximum 2.125 litres per 25kg bag) into the mixing vessel
• Add the contents slowly to the mixer
• Mix continuously for 6 to 7 minutes, ensuring smooth, even consistency
• Note: During the first 2-3 minutes, consistency will appear drier

Placing

Thickness capability: Conbextra TA can be placed in thicknesses up to 250 mm in a single pour, making it suitable for substantial grouting applications without multiple layers.

Placing procedure:

• Any bolt pockets must be filled with grout or resin prior to grouting between the substrate and base plate
• Continuous grout flow is essential
• The mixed grout should be poured only from one side of the void to eliminate air entrapment or surplus pre-soaking water
• Maintain grout head at all times to achieve continuous grout front

Pumping: For large volumes, Conbextra TA should be pumped. Prior lubrication of all equipment is necessary using a cementitious slurry made of two parts cement and one part water. Lubrication should be done at the same equipment location level, with pumping done immediately after lubrication.

Curing

On completion of grouting, exposed areas should be thoroughly cured using either Concure curing membrane or wet hessian and polythene sheeting.

Cleaning

Conbextra TA should be removed from tools and equipment with clean water immediately after use. Cured material can be removed mechanically.

Limitations and Precautions

Temperature restrictions: Conbextra TA should not be used at temperatures below 0°C or above 40°C. The substrate must be free of ice.

• When air or contact surface temperatures are 5°C or below, use hot water (30-40°C) to accelerate strength development
• At temperatures higher than 35°C, store mixed grout in the shade and use cool water (below 20°C) for mixing
• When grouting at temperatures below 2°C or above 35°C, contact the Fosroc Technical Department

Environmental exposure: Should not be exposed to moving water or rainfall during application and prior to final set.

Applicator requirements: Should only be used by experienced and qualified applicators.

Health and Safety

Chemical hazards: Conbextra TA is alkaline and should not come into contact with skin and eyes. Avoid inhalation of dust during mixing.

Personal protective equipment: Gloves, goggles, and dust mask should be worn during application.

First aid: If contact with skin occurs, wash with water. Splashes to eyes should be washed immediately with plenty of clean water and medical advice should be sought.

Fire hazard: Conbextra TA is not flammable.

Supply and Yield

Product code: Conbextra TA 25kg (MTO*): FC524476-25KG *Made to Order: Minimum order quantity: 800 x 25 kg; Lead time: 90 days

Yield: Each 25 kg bag of Conbextra TA will yield approximately 10.2 litres of grout. Allowance should be made for wastage when estimating quantities.

Storage and Shelf Life

Shelf life: Conbextra TA has a shelf life of 12 months from date of manufacture. Do not use if lumps are present in the product or if loss of workability is experienced (requiring more water to be added).

Storage conditions: Store in dry conditions in original, unopened packaging. If stored at high temperatures and/or high humidity, the shelf life may be reduced.

Related Products and Standards

Conbextra TA complies with EN1504-6:2006, establishing its suitability for structural grouting applications in wind turbine foundations. A Safety Data Sheet (SDS) is available from the Fosroc website and should be read carefully prior to use.

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References

• [1] Fosroc_Conbextra_TA_TDS.pdf
• [2] Fosroc_Conbextra_VG_TDS.pdf
• [3] Fosroc_Conbextra_BB92_TDS.pdf