Geogrid or No-Fines Concrete: Which Reinforcement Method Is Right for Your Retaining Wall?

20 August 2025

When planning a retaining wall using the Allan Block system, reinforcement plays a critical role in long-term stability - especially for taller walls or those subjected to additional pressures such as slopes or nearby structures. Two common reinforcement options are Geogrid reinforcement and No-Fines Concrete backfill. Understanding their differences can help you select the right solution for your site conditions.

 

Understanding Geogrid Reinforcement

Geogrid is a high-strength polymer mesh placed in layers behind the wall and embedded in well-graded compactible aggregate. This creates a reinforced soil mass that greatly increases the wall’s resistance to lateral earth pressure, enabling taller, safer, and more stable retaining walls.

While highly effective, Geogrid reinforcement requires excavation behind the wall equal to approximately 70% of the wall height, which may not be feasible on all sites due to space or property constraints.

 

When to Consider No-Fines Concrete

If space is restricted or boundaries prevent the necessary excavation for Geogrid, No-Fines Concrete offers an excellent alternative as it requires in comparison to Geogrid,  40% excavation relative to wall height. This method involves backfilling the Allan Block wall with specially formulated permeable concrete mix that allows water to drain freely while still providing substantial structural strength.

It’s a go-to solution for applications where excavation depth is limited, or where quick, engineered reinforcement is required.

Please note: Colinwell supplies Geogrid reinforcement but does not supply No-Fines Concrete. However, we can offer advice on the suitability of both methods for your project.

 

Which Method Is Right for You?

Criteria	Geogrid	No-Fines Concrete
Excavation space available	Required	Minimal needed
Wall height > 1.8m	Suitable	Suitable
Surcharge present	Excellent	Excellent
Poor soil conditions	Adaptable	Adaptable
Speed of installation	Moderate	Fast
Drainage capacity	With drainage pipe	Inherent in mix

 

Trust Colinwell for Technical Support

Whether you’re building a residential feature wall or a large-scale commercial structure, choosing the right reinforcement method is crucial for safety and longevity.

For walls over 1.2 metres in height or any commercial retaining wall, we strongly recommend speaking with our technical team. The Colinwell team will provide guidance based on your site’s specific constraints and performance goals.

Need help deciding?
Contact Colinwell today to discuss your project with our expert team.