86 | Crucial products hidden from sight 0800 Ducting’s Drossbach ducting was integral in the construction of the impressive new Parahaki Bridge on the Manawatū Tararua Highway. MANUFACTURING 0800 Ducting T T Russell Fredric “We’ve got the largest range of sizes in New Zealand, and every size we make we make a coupler to suit. We make the smallest and largest Drossbach available and are proud to use New Zealand steel.” Blair Chesman, owner of 0800 Ducting, which manufactures New Zealand’s largest range of Drossbach spiral-wound galvanised steel ducting for the precast concrete industry, says the most common application for the range of ducting is in concrete tilt slab panels and columns for multi-storey commercial and industrial buildings, bridge beams and abutments. “Our ducting is creating a hollow void in concrete for pre-stressing or post-tensioning or the use of starter bars,” Blair says. The ducting is crucial for the pre-stressing process, which involves applying tension to steel tendons within the ducting, inducing compressive forces in the concrete to enhance the concrete’s strength and durability. 0800 Ducting was established in 2004 by Kevin Badcock and John Chesmar, built on their shared knowledge and skills, and starting with an empty space in a shed with a dirt floor. After two years, the business moved to its current location in Villa Street, Masterton. Building code changes following the 2011 Christchurch earthquake generated increased demand for ducting, due to the requirements for more steel in construction, including for tie rods, starter bars and stressing cables for new and existing buildings. This demand was complemented by construction of motorway bridges nationwide, plus concrete reservoirs for towns and cities. The business is now solely owned by John’s son Blair, who employs two staff members – operations manager, Hadleigh Paku, and Blair’s sister, Robyn, who runs the office. The machine that forms the ducting was built by John, who passed away in 2016. “We are the pioneers of Drossbach ducting in New Zealand,” Blair says. The ducting is available in 10mm increments from 30mm to 150mm internal diameter as standard, plus 18 other sizes in between. “Our standard nominal length is 6035 millimetres, but it can be cut to any length required and joined with custom-made couplers to virtually infinite lengths and supplied with end caps and grout vents as needed. “We’ve got the largest range of sizes in New Zealand, and every size we make we make a coupler to suit. “We make the smallest and largest Drossbach available and are proud to use New Zealand steel.” Blair cites another key point of difference as being a fast turnaround, with overnight delivery available for morning orders for most of the North Island and some South Island destinations. 0800 Ducting’s Drossbach ducting was integral in the construction of the impressive new Parahaki Bridge on the Manawatū Tararua Highway, about 150 kilometres from the company’s workshop, and supplied during 2021 and 2022. The 300-metre-long cantilevered bridge has a width of about 30 metres, making it one of the widest bridges of its kind in the Southern hemisphere. It is on the new 11.5km highway between Ashhurst and Woodville, which opened in June. 0800 Ducting supplied 8.6km of 100mm diameter ducting, comprising 1400 six- metre lengths placed within the bridge’s concrete key structural elements, which included three piers and 54 deck segments. The combination of the spiral-wound profile of the ducting and the quality of the couplings can be important in the end application. For the Parahaki Bridge, it was pressure tested to 250kpa and found to have no leakage, Blair says. “It’s a massive bridge; it’s a work of art. It’s a pretty special thing to be a part of. People drive over it and they have no idea what’s inside it. Our product isn’t seen, so once it’s cast in concrete it’s never seen, but it’s got a purpose. “It’s a great feeling to know you’ve been part of something like that.” 0800Ducting Ltd Supply of spiral wound ducting to the precast concrete industry Spiral wound ducting is used to create a void in the precast panels or beams to allow starter bars, tie rods or stressing cables to be placed in the concrete. After tightening or stressing with hydraulic jacks, the concrete structures are much stronger. We supply the largest range in NZ from 30mm inside diameter up to 150mm inside diameter. We also supply end caps and grouting vents. 20 Villa St, Masterton | P: 0800 38 28 46 | E: office@800ducting.co.nz
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