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Nidaplast is the designer and manufacturer of the first extruded polypropylene honeycombs. The company markets these to sectors (e.g. composite structures or stormwater management) where strong, lightweight, yet inexpensive materials are required.
(Published on July-August 2008 – JEC Magazine #43)
RICHARD FILIPPI MARKETING AND DEVELOPMENT MANAGER NIDAPLAST
The Nidaplast Company currently has three divisions, all of which produce materials for the building and construction industry. Nidaplast Composites specializes in developing core for structural sandwich materials. Nidaplast Waters specializes in stormwater management for civil engineering applications and Nidaplast Eco-Garden, in stormwater management for landscaping applications. Nidaplast Composites has a broad range of solutions, from the simplest to highly technical ones. These are all based on two developments:
An infusion solution
Infusion has become a technical, reproducible and qualitycontrolled industrial process that is developing rapidly, especially in the wind turbine industry. After establishing its experience in standard processes such as hand lay-up and sprayup, Nidaplast Composites is now proposing Nidaplast® 8RI, a honeycomb solution for the infusion moulding process. The solution meets two important criteria, i.e. leak-tight cells during the infusion process and adequate resin flow to impregnate the skins on both sides of the sandwich, giving a resin distribution system that is just as efficient as other tried-and-true ones. This development has lead to a totally new product developed with a French leader for glass reinforcement Chomarat composites, the Rovipan®. It is an all in one sandwich reinforcement for vacuum infusion, combination of a nidaplast® 8RI and a glass reinforcement with an integrated flow medium (Roviflow®).
Structural sandwich panels using conventional materials
The Composites division also develops new applications combining Nidaplast®8 honeycomb with heavy conventional materials such as marble, fibre-reinforced concrete and steel.
These structural sandwich panels are both cost effective and environmentally friendly. They are stiffer than conventional materials, offering new characteristics such as thermal and sound insulation properties together with greater impact and fatigue resistance without any additional material. Their lighter weight also makes them easy to transport and install.
While retaining the surface finish of conventional materials, the new sandwich panels require less material. In terms of manufacturing, processing and utilisation, these low-weight materials contribute to sustainable development through their positive energy balance.
Sandwich panels as a substrate for natural stone
These panels covered in natural stone are three to four times lighter than standard equivalents, i.e. solid panels 15-20 mm thick. The mechanical performance of these lightweight panels is astonishing for this type of material. They not only are flexible, but can also bear maximum loads that are 8-10 times higher than can standard panels.
Ultra-light honeycomb structures for sustainable drainage system
Increasing urban development means more impermeable surfaces, creating problems for stormwater run off during peak flows. These flows can overwhelm standard sewage systems, increasing the risk of flooding and pollutant releases during heavy rains. To address this problem, Nidaplast Waters designed a range of polypropylene honeycomb solutions that it markets for stormwater management applications.
Nidaplast EP and Nidagreen EP are the first products in the range. These are 50-mm-cell, 1.5-m3 honeycomb blocks that are assembled and used to absorb the excess from peak stormwater flows. The patented EP system – the first of its kind in the field – works on a simple, unique principle. Burying these extremely lightweight honeycomb blocks (40 kg/m3), which have a 95% void volume and a compression strength of 30-60MT/m2, creates an underground retention basin that can store water during rainstorms. Another innovative aspect is that the system diffuses the water from the bottom, keeping the sediments and debris in the rainwater from entering the blocks. The EP system is the only one on the market that stays clean in the time.
In the UK, the system was subjected to a comparative study by the University of Sheffield’s Department of Civil and Structural Engineering. The test chamber was 3.6 metres long and 1.8 metre wide. The chamber was used to test both Nidaplast’s solution with supply from the bottom through an underpipe and conventional plastic boxes without underpipe. At a constant flow of 7 l/s, three different aspects were studied:
Results show that with the EP system with underpipe:
Computational Fluid Dynamics (CFD) software (version 6.1) was then used to simulate basin filling modes for two different configurations:
The following results were obtained: In the system without underpipe, the sediments, simulated by different-coloured traces, disperse and accumulate within the structure with the risk of clogging over time. In the system with underpipe, the sediments remain in the underpipe drain system, guaranteeing performance over time.
Rooftop stormwater storage
More recently, the Nidaplast Waters enlisted the skills of a specialist in flat roofs and leak tightness, Siplast-Icopal, to develop a new rooftop stormwater storage system in the form of a panel called Nidaroof®. The panel serves to store rainwater on flat roofs in urban areas, keeping runoff on roads and sidewalks to a minimum and, therefore, avoiding flooding and pollution.
The technique involves placing extremely lightweight polypropylene honeycomb panels that are covered with a porous geomembrane on the roof. The thickness required is 40-100 mm, equivalent to the water height produced by a rainstorm. This easy-to-install solution has good compression strength and is resistant to chemicals and micro-organisms. The panel is recyclable, and using it helps to maintain the humidity of the air in downtown areas at satisfactory levels.
These honeycomb materials can also be used to create permeable pavements to avoid sealing the surface. The Nidagravel line of products is designed for the purpose, and comes in the form of 37- mm-cell honeycomb panels covered on one side with a porous geomembrane. The honeycomb structures are laid down on a flat graded ground surface. The system provides the following advantages:
Honeycomb structures have recognized properties, especially in the aeronautical field. Nidaplast has harnessed the honeycomb concept to an inexpensive, environment-friendly material (polypropylene) and an industrial production process (extrusion) to develop a whole series of applications in the composite and other fields – without losing sight of today’s sustainable development objectives, i.e. preserving our resources in water and primary materials, and lowering our greenhouse gas emissions.