This invention is in the field of building materials for sustainable architecture and disaster resilient structures, especially against earthquakes. Clay is a cheap, eco-friendly material, but the high density and low strength of clay in its original condition have caused the buildings made of this material to collapse in several past earthquakes. However, if it can be made lighter and at the same time stronger, the buildings made of this improved material would receive less seismic forces, and would have more resistance and stability against earthquakes. Furthermore, the lightness of materials would lead to reduction in transportation and construction costs.
The main weaknesses of masonry buildings against earthquake, especially adobe and clay include:
The purpose of this invention is to improve the specifications of clay, as an eco-friendly, low-cost material with high workability, to present a better seismic behavior, by reducing its specific weight and increasing its resistance, particularly in tension, as well as its ductility, so that it can keep its integrity after cracking.
In an article entitled “An Innovative Technique of Improving the Soil Using Human Hair Fibers”, by Pillai and Ramanathan, in Proceedings of the 3rd International Conference on Construction in Developing Countries in 2012, it has been mentioned that by adding two percent of human hair to clay, its compressive strength is approximately doubled [1]. In another article entitled “An Innovative Method of Improving Subgrade Strength of Soft Soil Using Human Hair Fibers as Reinforcement”, by Patil and Harini, in International Journal of Scientific Research in Science, Engineering and Technology in 2016, it is stated that by adding 0.1% hair to the soil, its compressive strength increases by more than 70% [2]. Also, in another article entitled “Stabilization of Clay with Human Hair Fiber”, by Narayanan and Rebekah, in International Journal of Civil Engineering and Technology (IJCIET) in 2017, referring to human hair as a natural waste material, it has been stated that hair is non-biodegradable and that the compressive strength of clay by adding 1.2% human hair increase from 125 to 209 kg force per square centimeter [3].
The innovation of this invention is high mechanical strength and low specific weight of FHRC material, and the ability to maintain its integrity even after cracking.
FHRC is made of the combination of 73% clay passed through the sieve No. 25, 24% water, 1.5% foam, and 0.5% natural hair fiber pieces approximately 1.5 to 2 cm long. The steps of making FHRC material are as follow:
By this invention, for the first time the combined usage of lightening admixture and reinforcing fibers is addressed, resulting in a fully indigenous and economical material that is easily usable, and its specific weight is 1.5 times less than the normal clay (the specific weight of clay in normal compacted conditions is close to 2). The foam material used in FHRC can be natural- or artificial-based materials. FHRC is stronger than ordinary clay in shear, bending and compression, respectively, 4, 6 and 1.5 times on average.
FHRC has also more insulation capability against heat, sound and moisture than ordinary clay, thanks to its high porosity and also high resistance of clay to heat. In the event of a fire, FHRC can keep healthy the strands of hair inside the material. High heat capacity also helps to store energy in the building that is an important feature of sustainable architecture. Finally, FHRC is more resistant to moisture than traditional clay, and can be used in various parts of the building including:
FHRC can be used in all types of conventional buildings as the main material for the construction of exterior and interior walls, false ceiling tiles, flooring and even load bearing walls in traditional masonry buildings, preventing the buildings from collapse, even after cracking, which as a result, save human lives. Using this material would also extend the useful lifespan of the building as well as that of walls and ceilings of the buildings retrofitted by this material.
It is also worth mentioning that since the integrity of the whole building cannot be kept, if parts of it are made of traditional blocks or bricks, even if the used mortar is strong enough. This is while the materials of this invention can be used to build different parts of buildings without the need for mortar even for rural homes. On this basis, FHRC can be used for the construction of new buildings as well as the restoration of the monuments.
High performance and moldability can be considered as another advantage of FHRC material. This merit makes it easy to work with the material in the factory for manufacturing, and also at the construction sites. FHRC material is also suitable for prefabricated building elements, which their use increases the speed of construction. FHRC can also be used for creation of different types of building components, even decorative elements, in different shapes and sizes.
Finally, a little moisture inside the building can make the FHRC create a good scent, which is usually felt after rain in dry areas, and give the building users a great feeling. Due to the color of the materials of this invention, if dark appearance is not desired, it can be easily painted and coated with a thin layer of material such as plaster.
Some useful pictures are provided in a separate file, which help to better understand the specifications and features of the FHRC material.
Pillai, R.R. and Ramanathan, A., 2012, July. An innovative technique of improving the soil using human hair fibers. In Proceedings of the 3rd international conference on construction in developing countries (pp. 4-6).
Patil, P. and Harini, H.N., 2016. An innovative method of improving subgrade strength of soft soil using human hair fibers as reinforcement. International Journal of Scientific Research in Science, Engineering and Technology, 2(4), pp.551-554. Science, Engineering and Technology, Volume 2, Issue 4, 551-554 (2016).
Narayanan, K.S. and Sharmila, S.M.R., 2017. Stabilization of clay with human hair fiber. International Journal of Civil Engineering and Technology (IJCIET) Volume, 8.
Filing Document | Filing Date | Country | Kind |
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PCT/IB2020/055774 | 8/19/2020 | WO |