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Does papercrete fulfil the increased needs of a façade cladding technology?

Papercrete is an experimental material which replaces an amount of cement with paper in the normal concrete mix. Concrete is the most commonly used material in construction. Its annual energy consumption exceeds that of all the other engineering materials. An estimated five to eight percent of the world’s carbon emissions coming from the concrete industry. Concrete industry is constantly looking for new ways to create lighter more ecological friendly products. Adding mineral fibres or foam are the most common ways.

Annual consumption of energy

The total weight, the cost and the CO2 emissions during production are reduced. Its use remains limited, because of the lack of official data about its structural behaviour, mechanical properties and durability. In order to bring papercrete closer to standardization further experimentation is needed.

The research is material based, and aims to define the limiting properties and set the main design principles. Results showed that papercrete meet most of the façade cladding systems requirements. It is a lightweight material (7 times lighter than concrete) with good heat and acoustic insulation properties and big variety on shapes, colours and textures. Papercrete though, is a new material and like all the new materials there is a period of time which its applications are limited because the manufacturing, processing and construction techniques are still not developed enough to facilitate its use.

Papercrete is a properties limited material. These properties will define whether if can be used as a façade cladding material or not. Adding reinforcement (fibres or metal mesh in the mesh) to improve the mechanical properties, changing the manufacture process (use less water-ovens) to minimize the drying period and increase the strength and prefabricating the panels in a controlled environment and moving them in situ when needed are the first steps towards standardizing the process and improving the quality. Papercrete is a property limited, materialThere are significant challenges going into business with papercrete but also opportunities. Deep knowledge in material properties and long term liability, advance in processing and building aspects, in combination with future material technology, will bring papercrete closer to standardization. Getting a building permit will become easier, will attract more investments, and eventually papercrete will be commercially accepted.

http://www.youtube.com/watch?v=XYv2POqyz0c


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PaperKrete production

Papercrete is easy to produce but requires accurate measurements. It is important to weight the newspapers before soaking them. The standard process to make the mix is:
• Soak newspaper in water overnight to soften the fibres and make mixing easier.
• Mix the soaked paper until it becomes a homogeneous pulp.
• Add Portland cement, sand and water.
• Blend into a concrete mixer or similar machine (Papercrete Tow-Mixer) the ingredients until the mix becomes a thick consistent pulp.
• Pour mix into forms (wooden or metal) to create blocks of any size and shape. To maximise the benefit of re-use of moulds, steel moulds must be used. They have long life span providing thousands of re-uses and also reduction of waste.
• Remove the forms (after 7 days in a wet climate)

http://www.youtube.com/watch?v=XYv2POqyz0c

1.Make wooden forms…

…or use the plastic forms used to make concrete


2.Soak newspaper overnight

3. Make the paper pupl (I used x-shaped head drill)

3. Weight cement and sand

4. Pour cement and sand into the paper pulp

5. Mix all the ingredients for approx. 10 minutes6. Pour the mix into the wooden or plastic forms

7. Vibrate the mix to remove the air

8. Let the specimens dry for at least one week ( Drying time varies in different climates and water content percentage on the mix)

9.Remove forms

10. Clean the forms and the Laboratory

11. Let the specimens dry for 2 week more (drying time varies fot the same reasond mention above) to take their final properties.



12. Specimens ready to be used or tested

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Anisotropy

Specimens don’t shrink symmetrically. The process of making the pulp (drill with special x-shaped head) distributes the fibres unevenly. From the existing specimens I could not define a dominant direction. Anisotropic materials properties vary with the direction of measurement( e.g. Thermal expansion coefficient)

 

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Acknowledgments

This report is a research on Precast Papercrete Facade Panels (PPP), as part of my graduation project for the master program of building technology department in TU Delft.
This result wouldn’t be possible without advice, constructive criticism and ideas from others. I would particularly like to recognize suggestions made by my two mentors Dr.Ir. F.A. Veer, Peter van Swieten and acknowledge their willingness to help. I would also like to thank A. Borgart, Dr.ir.R.M.F Stouffs and M. Yurrin for their assistance in the early stages of the project during the course “Stand Up Architecture”.
The staff of the concrete Lab in Civil Engineering Faculty and Kease were always helpful when I asked for their assistance. Equally valuable has been the contribution of numerous colleagues and friends. A. Petalas, G.Chatzikonstantinou D. Papadopoulou and D. Baltoukas helped me with our long – and/but – constructive discussions during the project.
Thank you to all who assisted in collecting newspapers needed (more that 200Kg in total):
Efi Ntefi
Marco Alvarez
Ifigeneia Dilaveraki
Karolina Konecka
Teo Klouva
and Ari Goula for assisting me finding the chemicals used.
Thanks also to A. Kourkoula, M. Kokkinou, M. Bittermann, R. Bokel, Barry Fuller, M. Tenpierik for their helpful comments and J. Rhemrev for her patience. Finally, my ongoing debt to my family for their continuous moral encouragement and financial support.

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Compressive and bending strength

Papercrete, especially the untreated one, has poor mechanical properties. The compression and bending test gave the following information.

σpapercete≈0.90 Mpa (1/25 normal concrete, lower than soft woods)
3 phases elastic-plastic-after starting to crumble becomes stiffer

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Availability and processibility

Papercrete is made from materials widely available and easy to found. Paper comes from a variety of sources and is usually without cost.

Manufacturing processes are still not developed enough to facilitate its use. If we decide to go into market with papercrete the process must adjust to the requirements of fast and mass production. The components must be manufactured by industrial methods to build a large number of panels in a short time at low cost.
Specialized personnel with the technological know-how and the necessary experience to provide quality and time lasting assurances is needed. Building mixers must become commercially available. We also have to reconsider the paper pulp used because the needs will be much bigger and the cost might increase.
Papercrete is a soft material so it can be easily processed after it is hardened. Processing might create cracks. Panels may be cut with a circular saw; a precision tipped blade is recommended.

The porosity of the material creates a very interesting texture. Papercrete is available in many standard colours, textures and finishes. Because of this relative porosity delicate designs can not be created.
The range of finishes and the quality control in precast elements is wider than that available for in-situ work. The materials used to cover the exterior surface (for waterproofing, colouring etc) must let the air to evaporate because if water is trapped inside will create moisture problems and the panel will start to rotten.
Papercrete can be moulded into almost any form and finish. Custom-made forms were used to create panels in the precise dimension and shape. These forms introduce reveals, joints, patterns, and other expressive detailing to the panel surface. Specific colour effects and texture can be achieved through varying sands, aggregates, and pigments.
Colorants increase the price and affect the physical and mechanical properties. Weight is increased (around 10%), specimens shrink more (5% more). Testing must be made to find out the effect on strength

Papercrete is a soft material and processing is easy.

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Cost-effectiveness

The total cost vary depending what kind of additives or reinforcement is used in the mixture. The untreated mixture lies in the cheapest end of lightweight concretes. Colorants, water and fire sealants increase the price.

Low cost materials, lie to the left of the chart.Cheap stiff materials lie towards the top left of the chart – mostly metals and ceramics. Concrete is cheap and stiff – ideal for structures.

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