Flowable Non Shrink Grout Explained
Flowable non shrink grout is a specialised cementitious grout designed to flow easily into narrow gaps and confined spaces while maintaining volume stability after curing. It is widely used in structural and industrial applications where complete contact, high strength, and precise load transfer are critical. This article explains what flowable non shrink grout is, how it works, where it is used, and why it is preferred over ordinary cement grout in demanding applications.
What Is Flowable Non Shrink Grout?
Flowable non shrink grout is a pre-packed, factory-formulated grout that produces a highly fluid consistency when mixed with the correct amount of water. Despite its high flow, it does not segregate or bleed excessively and is engineered to compensate for shrinkage during curing.
Unlike conventional grout, which may shrink and pull away from contact surfaces, flowable non shrink grout maintains full contact with concrete and steel elements, ensuring effective load transfer.
Key Characteristics of Flowable Non Shrink Grout
Flowable non shrink grout has specific properties that distinguish it from other grout types.
- High flowability without vibration
- Controlled expansion to prevent shrinkage
- Good compressive strength after curing
- Excellent filling of tight gaps and voids
- Stable consistency with minimal segregation
These characteristics make it ideal for precision grouting applications.
How Flowable Non Shrink Grout Works
Flowable non shrink grout works by combining controlled expansion additives with carefully graded aggregates and plasticisers.
- Plasticisers improve flow without adding excess water
- Shrinkage-compensating agents counteract drying shrinkage
- Graded aggregates ensure dense packing and strength
As a result, the grout flows easily into confined spaces, fills the entire cavity, and hardens without volume loss.
Difference Between Flowable and Ordinary Grout
Flowable non shrink grout performs very differently from ordinary cement grout.
- Ordinary grout relies on excess water for flow, causing shrinkage
- Flowable non shrink grout achieves flow through formulation, not water
- Ordinary grout may leave voids under base plates
- Flowable non shrink grout ensures full contact and load transfer
Common Applications of Flowable Non Shrink Grout
Flowable non shrink grout is widely used where precise filling and load transfer are required.
- Machinery base plates and equipment foundations
- Large steel base plates
- Precast concrete seating
- Bridge bearings
- Anchor bolt pockets with tight tolerances
Advantages of Using Flowable Non Shrink Grout
Using flowable non shrink grout offers several benefits.
- Eliminates voids beneath base plates
- Improves load distribution and structural stability
- Reduces vibration in machinery installations
- Minimises rework and long-term maintenance
- Provides consistent and predictable performance
Mixing Requirements for Flowable Grout
Correct mixing is essential to achieve the desired flow and strength.
- Follow recommended water quantities strictly
- Use mechanical mixing for uniform consistency
- Avoid adding extra water to increase flow
- Mix until lump-free and homogeneous
Improper mixing can reduce strength and negate shrinkage compensation.
Placement Method for Flowable Non Shrink Grout
Proper placement ensures complete filling and performance.
- Prepare and clean all contact surfaces
- Pre-wet concrete to saturated surface dry condition
- Install leak-proof formwork
- Pour grout continuously from one side only
- Allow grout to flow naturally without vibration
Curing of Flowable Non Shrink Grout
Curing improves strength development and durability.
- Protect grout from rapid moisture loss
- Use curing compounds or wet coverings
- Maintain curing for at least 3–7 days
Limitations of Flowable Non Shrink Grout
While highly effective, it must be used correctly.
- Not suitable for sloped or vertical surfaces without formwork
- Higher cost compared to ordinary cement grout
- Requires strict control of water content
Common Site Mistakes to Avoid
- Adding excess water to improve flow
- Poor sealing of formwork
- Interrupted grout placement
- Early loading before strength gain
Frequently Asked Questions (FAQ)
1. Is flowable grout weaker than stiff grout?
No, when mixed correctly it meets required strength levels.
2. Does flowable grout shrink?
No, it is designed to compensate for shrinkage.
3. Can flowable grout be pumped?
Some formulations are suitable for pumping; check product suitability.
4. Is vibration required for flowable grout?
No, vibration should be avoided.
5. Where should flowable grout not be used?
It is not suitable for unconfined or vertical applications without formwork.
Raltro
Raltro is a construction materials knowledge platform focused on explaining how specialised products behave in real construction environments. By detailing what flowable non shrink grout is, how it achieves high flow without shrinkage, and where it delivers the best performance, Raltro helps engineers and contractors select the right grouting solution for precision applications, avoid common site mistakes, and achieve reliable, long-term structural support.