SandMax BDU - Concrete Filled Geotextile Mattress
SandMax BDU
SandMax BDU is a geotextile mattress formed by filling the space between two layered polypropylene geotextile fabrics with fine aggregate concrete. SandMax BDU is laid empty on site and, once positioned, fine aggregate concrete is pumped between the two geotextile layers. The weaving points that connect the layers ensure the mattress expands to a consistent thickness and uniform cross section during filling. When the concrete sets, a continuous and flexible cover layer is formed that sits fully against the surface. Since formwork installation, joint detailing and on site concrete transport are eliminated, the work is completed in a significantly shorter time compared to conventional grouted riprap and concrete slab applications.
SandMax BDU Functions
SandMax BDU forms a permanent, cast in place concrete cover on surfaces in contact with water. Because it works by being filled on site without the need for formwork, it delivers fast construction, minimum labour and low cost across a wide range of scales, from stream rehabilitation to coastal structures and deep sea discharge lines.
Stream and River Rehabilitation
It covers the bed and slope surfaces, preventing flow induced scour and cross section deformation. Since the mattress conforms to the natural geometry of the bed, rehabilitation can be carried out without narrowing the cross section. Requiring no formwork, it noticeably shortens construction time on long stretches.
Coastal Protection
On shorelines under continuous wave and current action, it seals the ground surface and prevents wave energy from reaching the soil directly. The weight of the concrete fill keeps the cover in place, while its flexible structure adapts to base settlement and reduces the risk of cracking.
Deep Sea Discharge
It covers discharge and pipelines laid on the seabed, protecting them against currents, scour and external impact. As it can be filled underwater, no dry site conditions are required, and it provides the additional weight needed for line stability.
Filter Point Structure That Releases Water Pressure
The mattresses are woven at regular intervals to create filter points. These points act as filters through which water can be discharged and the water pressure behind or beneath the bed can be released. The small pore size prevents the migration of fine soil particles. As a result, water pressure that could otherwise build up beneath the cover and create an uplift effect is released in a controlled manner, preserving the long term stability of the cover.
SandMax BDU Features
- Provides a much thinner cross section cover compared to stone revetment and grouted riprap
- Works with the cast in place filling method, requiring no formwork installation or on site concrete transport
- Can be installed and filled underwater, requiring no dry site conditions
- Can be installed on steep slopes without difficulty
- Settles onto the subgrade during filling, conforming to complex geometries and irregular surfaces while reducing scour potential
- Maintains an equal cover thickness at every point regardless of the slope
- Shortens project duration significantly thanks to its high daily construction rate
- Serves as an economical alternative to conventional methods such as riprap, grouted riprap, gabions and concrete slabs
- Offers an aesthetic appearance with its smooth and continuous surface
Frequently Asked Questions
1. What Is SandMax BDU?
It is a geotextile mattress formed by filling the space between two layered polypropylene geotextile fabrics with fine aggregate concrete. When the concrete sets, a continuous and flexible cover layer is formed that sits fully against the surface.
2. How Is SandMax BDU Installed?
The mattress is laid on the surface to be covered, secured in place, and fine aggregate concrete is pumped between the layers. Since no formwork installation or on site concrete transport is required, the application takes far less time than conventional methods.
3. Can SandMax BDU Be Installed Underwater?
Yes, the product can be laid and filled underwater. This eliminates the need for dewatering and cofferdam works in areas such as the seabed, stream beds or canal interiors.
Yes, the product can be laid and filled underwater. This eliminates the need for dewatering and cofferdam works in areas such as the seabed, stream beds or canal interiors.
Its main application areas include the rehabilitation of streams, rivers and canals, coastal protection structures, deep sea discharge lines, subsea pipeline and cable protection, and slope lining. It is also preferred for scour protection at bridge piers and culvert outlets.
5. What Is the Difference Between SandMax BDU and Grouted Riprap?
Grouted riprap requires formwork, on site concrete transport and intensive labour, whereas SandMax BDU needs none of these as it works with the cast in place filling method. It also provides a thinner cross section cover, and its flexible structure reduces the risk of cracking.
6. Does SandMax BDU Maintain Its Thickness on Sloped Surfaces?
The weaving points connecting the layers ensure the fill remains at an equal thickness at every point. For this reason, no thinning or accumulation occurs in the cover thickness even on steep slopes.
