The Role of Membranes

Background

GEOTEXTILES, or MEMBRANES as they are more commonly referred to, are an invaluable asset in today's modern construction techniques, and are used in numerous groundwork projects where filtration, drainage, protection, separation, soil stabilization, reinforcement and durability are required.
 

By strengthening & stabilising the sub base and preventing costly aggregates from being pushed into the sub grade soil, membranes effectively separate the different layers and thus prevent intermixing, whilst allowing surface water to pass through into the drains.

Types of Membrane

There are two basic types of geotextile membranes, woven & non-woven.

• WOVEN are tapes of polypropylene multi-woven together to create a high mechanically strong porous material. Ideal under the hardcore base of an arena/gallop, providing both excellent puncture resistance and water flow, but are not recommended directly under the riding surface.

• NON-WOVEN are fibres of polypropylene bonded together and needle punched to allow water flow and have good filtration properties. These types are of particular benefit directly under the riding surface as they can eliminate the need of a blinding layer of small stone on the hardcore base. Due to the fleecy nature of the material wood products, sand & pvc or sand & rubber mixes grip the fibrous material enhancing the performance by helping to eliminate slippage. The needle punching also retains the fine particles of sand whilst allowing the water through thus reducing the wash out of fines into the drainage.
   

All-weather Riding Arenas and Gallops

One of today's most common applications is in the construction of all-weather riding arenas, where a combination of the qualities of puncture resistance, drainage, high tensile strength, and separation are of paramount importance in preventing the costly intermixing and contamination of the riding surface by the drainage materials from below, through the continuous action of the horses' hooves.

Membrane Myths

In arena and gallop applications many people have had the unfortunate experience of their membrane coming through the surface; this is due to poor installation and maintenance.
When using a membrane under the riding surface the joints should be secured together either by double-sided tape, stitching or tying to prevent the top surface being pushed under the membrane by hoof action and consequently lifting the membrane up.
The membrane should be attached around the four sides to the kickboards or fence posts etc., between timber battens.
The depth and evenness of the surface needs to be maintained regularly by raking or harrowing, and topped-up as required.