[Ferro List] Laminated concrete

[paul at ferrocement.net]

>
Hi Chris and All,

Michael Pemberton learned LFC from Martin Iorns' and is his licensee in
Great Britain. He constructed the FC 'leaves' for the roof of the Menil
art museum.

Paul

> http://findarticles.com/p/articles/mi_qa5379/is_200107/ai_n21476766
>
> here is the article, no pics on site
>
>
> Laminated concrete for efficient construction
> Concrete,  Jul/Aug 2001  by Pemberton, Michael
> E-mail Print Link Laminated concrete and laminated ferrocement consist of
> successive mortar layers with reinforcing mesh embedded in each layer
> while the mortar is still soft. The mortar is applied by spraying and a
> special roller tool rapidly embeds the mesh. Embedding results in high
> concentrations of reinforcement, eliminating the voids that occur when
> reinforcement is placed before concreting. Laminated ferrocement is
> designed in accordance with ACI 549.1R-93 Guide for the design,
> construction and repair of ferrocement, where it is defined as "a form of
> reinforced concrete using closely spaced layers of mesh and/or small
> diameter rods completely infiltrated with, or encapsulated in, mortar".
>
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> More » The process of laminating ferrocement and concrete provides an
> alternative way of making and applying quality concrete to improve upon
> accepted construction practice. The result can be a better, more
> costeffective product for appropriate structures, and offer more
> flexibility in design and finish.
>
> Ferrocement, the first first form of reinforced concrete, is made in
> sections 30-40mm thick. Small ferrocement boats made by Lambot in 1848 can
> be seen at the Musee des Travaux Publics, Paris and another, reported to
> have floated for a century in the Pelican Park at Amsterdam Zoo, is on
> display in The Netherlands. Since then, knowledge of cement materials has
> developed, along with methods of improving quality and performance.
>
> Why laminate concrete?
>
>
>
> Timber can be laminated to make plywood, metals can be laminated to make
> special steels and plastics can be laminated to make composite materials.
> In each case, the laminating process produces a better product in terms of
> quality and strength/weight ratio. The same applies to laminating
> concrete.
>
> Laminating concrete is a very effective use of concrete materials:
> techniques of spraying and laminating were developed by Iorns and Watson
> in Sacramento, California in the 1960s, when many large ferrocement yachts
> and marina pontoons were built. In India, the material has been used to
> build pontoon bases for floating hotel cabins (see Figures 1-4). It has
> also been used in Canada and in the UK for floating piers, and on such
> buildings as the De Menil Museum, Houston (see front cover and Figure 5).
>
> Sprayed and laminated ferrocement sheathing - the protective layer for
> applications of concrete and more reinforcement - can be applied to
> lightweight forms that are less costly and easier to support. The process
> of spraying mortar drives off surplus water and produces a well-compacted
> layer with a low water/cement ratio at the surface of the structure, where
> the 'quality' concrete is required (see Figure 6). Small meshes are
> embedded close to this dermis, which controls cracking. When combined with
> the subsequent embedding of more reinforcement, the steel is positioned
> away from the neutral axis, making the most efficient use of the
> reinforcement.
>
> The sprayed mortar or concrete can be modified to include polymers, fibres
> or admixtures, and textured moulds and colour pigments can be used to
> adjust the appearance. No other method of concrete manufacture can
> economically provide the engineers and designers with such a choice of
> concrete material quality, steel reinforcement contents and surface
> colours or textures. By combining precast elements, spray-welded together,
> a substantial cellular structure can be configured. The cells of such a
> structure can become the permanent shuttering for concrete placing.
>
> These techniques are particularly appropriate to the construction of large
> cellular marine structures that are required to support devices for
> extracting wind, wave and tidal energy (see Figure 7). As the structures
> can be constructed in sheltered waters from floating moulds, sites
> relatively close to areas where installations are required can be
> selected, obviating the need for dry docks and reducing towing charges.
> Very large structures, either of the floating or gravity type, are
> required to support the devices that extract wind, wave and tidal energy.
>
> The use of laminated ferrocement and concrete for applications that can
> increase the use of renewable energy provide an opportunity for
> engineering consultants and construction companies to make a contribution
> to the reduction of global warming and sustainability of finite resources.
>
> Further reading
>
> NAAMAN, A.E. Ferrocement and laminated cementitious composites.
> TechnoPress 3000, Michigan, 2000. 367pp. (see CONCRETE, May 2001, p.12 for
> review).
>
> Author's notes
>
> Laminated ferrocement refers to SOmm thick or less
>
> Laminated concrete refers to sections SOmm thick or more
>
> The process of spraying and laminating concrete, together with associated
> systems of floating moulds, ferrocement slipforming and sequential
> construction are the subject of patents and licences registered in the
> names of Martin Iorns and Michael Pemberton.
>
> References
>
> ACI COMMITTEE 549. ACI 549.18-93. Guide for the design, construction and
> repair of ferrocement. ACI, 1993. 30pp. (A new model code is being
> prepared by the International Ferrocement Society. Address: IFIC/AIT, GPO
> Box 2754, Bangkok, Thailand, www.ait.ac.th/clair/)
>
> 123Next »
>
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