Longbeach Boatshed, Marlborough Sounds

Product	Location	Supplied	Architect	Contractor	Photography
Engineered Concrete Solutions	Longbeach Bay, Marlborough Sounds	50 MPa marine concrete mix	Arthouse Architects	HR Construction	Matthew Croad Photographer (construction)
					Simon Devitt (completion)

Project Engineered Concrete Solutions
- ProjectEngineered Concrete Solutions
- LocationLongbeach Bay, Marlborough Sounds
- Supplied50 MPa marine concrete mix
- Architect Arthouse Architects
- Contractor HR Construction
- Photography Matthew Croad Photographer (construction)
Project Longbeach Boatshed, Marlborough Sounds
- Project
- Photography Simon Devitt (completion)

Concrete by Barge: Longbeach Boatshed, Marlborough Sounds

Delivering concrete is not always as simple as backing a truck up to site.

The Longbeach Boatshed, walkway and jetty sit directly on the waterfront in the Marlborough Sounds. Designed by Arthouse Architects and constructed by HR Construction, the project called for a simple, low-maintenance building that would sit recessively within its coastal surroundings while responding to the character of the existing property.

The project also presented an unusual construction challenge: access.

With the site reached from the water, delivering concrete for the foundations required careful coordination between Allied Concrete, HR Construction, barge operator Nautilus Pacific and Pumprite Concrete Services.

Getting concrete across the water

In May 2020, Allied Concrete’s Blenheim team supplied approximately 35.9 m³ of concrete across seven truckloads for the project.

Rather than travelling directly from plant to site, the Allied trucks were transported by barge. The delivery was timed with the tides so the barge arrived at high tide, allowing it to get as close to shore as possible. Once in position, the trucks reversed towards the opening at the end of the barge to discharge into the concrete pump operated by Pumprite Concrete Services.

From there, the pump boom extended across the water towards the shore. Additional hose provided the reach required for HR Construction’s team to distribute and place the concrete throughout the foundations.

It was a delivery method that required each part of the operation to work together, from batching and dispatch in Blenheim through to transport, barge movements, pumping and final placement.

A technical mix for a coastal environment

The project used a 50 MPa marine concrete mix incorporating microsilica.

With the additional journey between plant and placement, maintaining the workability of the concrete was an important consideration. Slump and retarder requirements were carefully managed so the concrete remained suitable for pumping and placement after transport from the Blenheim plant and across the water to site.

The coastal location placed particular demands on the concrete itself. Fraser Thomas designed the reinforced concrete foundations and slab with a special marine mix to provide durability against the site’s corrosive marine conditions.

The 50 MPa mix supplied by Allied Concrete incorporated microsilica, which helps produce denser, less permeable concrete and improves resistance to chloride ingress, supporting the long-term durability of reinforced concrete in marine environments.

Engineering for the project was undertaken by Fraser Thomas.

Planning beyond the concrete

Delivering ready-mixed concrete by barge introduces considerations that aren’t present on a conventional site.

Alongside maintaining the properties of the concrete throughout the extended delivery, the operation required planning around truck and barge movements, positioning for discharge, pumping equipment, marine conditions and communication between the different teams involved.

Allied’s procedures for barge-based concrete deliveries provided a framework for managing the additional health and safety risks associated with transporting and discharging concrete in this environment.

The result was a coordinated foundation pour that brought together specialist concrete supply, marine transport, pumping, engineering and construction to overcome the challenges of a unique waterfront site.

Project team

Project: Longbeach Boatshed
Location: Longbeach Bay, Marlborough Sounds
Builder: HR Construction
Architect: Arthouse Architects
Engineer: Fraser Thomas
Concrete supplier: Allied Concrete, Blenheim

Photography: Matthew Croad (construction) / Simon Devitt (completion)
Barge operator: Nautilus Pacific
Concrete pumping: Pumprite Concrete Services