Culvert Bags

Culvert Bag Storm Water Protection on the Wellington Expressway

Culvert Bags are the easy retaining wall solution many New Zealand construction companies and property owners are turning to obtain watertight walls that offer a short setting time but with maximum strength that won’t come crumbling down after a few years. This cost-effective solution can be laid down in a variety of ways that isn’t just a functional retaining wall but can be an attractive or even creative feature of your property. We’ve created a unique blend of concrete that makes it extremely strong, fast setting – but also cost-effective. 

Our latest project saw a watertight scruffy dome come to fruition on the Peka Peka to Otaki leg of the Wellington Expressway, protecting their stormwater system for years to come.

As pictured, culvert bags can be expertly laid in other shapes than a straight line, giving your construction project maximum fluidity and creativity when designing the retaining wall you want while keeping it true to its function. This makes culvert bags perfect for retaining walls and floodwalls that line curved driveways, natural rivers and landscapes for a more organic finished look. For rural areas in New Zealand, culvert bags are the easy, affordable solution for a multitude of project applications.

What are Culvert Bags?

Mastermix Culvert Bags are pre-made bags packed with a specifically manufactured concrete mix that can be laid a bit like bricks along riverbanks, erosion points, sea walls, dams and other areas that need strong, watertight retaining walls and stabilisation work. These walls protect waterways and stormwater drains from becoming blocked by soil erosion. With a little inspiration from online sources, Culvert Bag retainer walls can be designed and placed by yourself on your property if there are areas you need to protect from natural elements, or as an aesthetic and functional choice to line any part of your property. Once in place, the bags are secured by spearing them through with strategically placed y posts, basalt or steel rods. They are easily handled, being 25kg per bag, and once laid down, are hosed down and left to the elements to harden and become the permanent structure required of them.

Keeping New Zealand Green

The bag surrounding the concrete mix is made of biodegradable polypropylene, meaning it is safe to come away and be absorbed by the environment. The bags will start to come away after being exposed to the elements and can be helped along by hand if required once they have started shedding naturally. We believe in sustainable products and future-proofed business as we move even further to completely adapt our concrete products and accessories to be as reusable, biodegradable and recycled as possible.

Cost-Effective Alternative to Pre-Cast Concrete or Crib Walls

The 25kg culvert bags are designed to achieve a square metre coverage of 17-19 bags per m2 and are suitable for so many applications, rural or otherwise. It’s a kind of concrete that is very manageable and designed for establishing stable structures in construction and especially around waterways. Besides water and erosion protection, culvert bags can also be used in the soft part of gravel roads to give a hard concrete base for traffic to pass by safely – essential in more rural areas that don’t necessarily need a paved road.

Water Protection

New Zealand has an abundance of water that we love to build on, so any structure near water needs a retaining wall and concrete construction that keeps water levels from damaging structures. Our clients include Fulton Hogan, Higgins, Fletcher Forests, McBreen Jenkins, Downer NZ LTD, as well as many local bodies who use our culvert bags to protect bridges, dams, stormwater systems, rural farms, rivers and anywhere that risks flooding or erosion in the rainy seasons.

Want to talk about your next retaining wall solution? We are in the business of making it very easy for you to order exactly what you need and get your concrete solutions that last.

Phone or email our friendly expert team today.

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