Linking A World Tradition With Modernity
APPROPRIATE BUILDING TECHNOLOGIES BASED ON EARTH
This research aims at making extensive use of stabilised raw earth as the main building material, thereby using a local resource to help develop technologies that are energy saving, eco-friendly and sustainable. The main research and development is focussed on minimising the use of steel, cement and reinforced cement concrete. Note that these technologies are seen only as tools for creating a safe, comfortable, progressive and aesthetic architecture.
Compressed Stabilised Earth Block (CSEB)
A wide range of equipments for building with earth, including the Auram equipment, has been researched and developed
Sustainable Buildings 175 from the very onset by the Auroville Earth Institute. It ranges
from a press for compressed stabilised earth blocks, quality control devices for block making, handling equipment, hand tools, scaffolding, to rammed earth equipment.
The press 3000 is today being sold worldwide – mostly in South Asia and in Africa. A few machines have also been sold in Europe, USA, Arabic peninsula and China. The press 3000 with hollow interlocking moulds was sold in large quantities to Gujarat-India, for the rehabilitation of the zones affected by the severe earthquake of January 2001.
The Auram press 3000 is a multi mould manual press which can fit 16 moulds on it, for producing about 70 different types of blocks, with various shapes and thicknesses. CSEB made in Auroville with 5% cement, have an average dry compressive crushing strength of 50 kg/cm2 (5 Mpa)
and a wet compressive crushing strength of 25 kg/cm2.
The water absorption is around 10%. Country fired bricks have around 35 kg/cm2 for the dry compressive strength
and 12% water absorption. Stabilised Rammed Earth
The soil is mixed with sand and stabilised with an average of 5% cement. The mix is rammed by hand. Foundations are rammed directly in the trench. It is the cheapest and fastest way to do a foundation.
Walls are rammed in between formworks, based on “slipping forms made of plywood reinforced by wooden members. Composite Basement And Plinth Beam
Basements are made with CSEB blocks with 5% cement. The plinth beam is cast into a U shaped CSEB. Reinforced cement concrete is cast in the U shape blocks and this is a very neat and efficient way to do a plinth beam.
The latter acts also as a damp proof course. Composite Columns
Round hollow CSEB are reinforced with cement concrete. Reinforcements vary with the height and load, but the rod diameter cannot exceed 10 mm for the blocks 290 and 12 mm for the blocks 240.
Table 1 – Comparison of building materials in Auroville (September 2006)
ENVIRONMENTAL COST MONETARY COST STRENGTH
CSEB and RE are more CSEB and RE always CSEB and RE are: eco-friendly than fired bricks cheaper than fired bricks
Pollution emission: A finished m3 of CSEB wall is: 1.4 times stronger than
2.4 times less than wire cut bricks 19.5 % cheaper than country fired bricks country fired bricks 7.9 times less than country fired bricks 45.5 % cheaper than wire cut bricks
Energy consumption: A finished m3 of RE wall is: 0.5 times weaker than
4.9 times less than wire cut bricks 21.9 % cheaper than CSEB wall wire cut bricks 15.1 times less than country fired bricks 37.1 % cheaper than country fired bricks
57.4 % cheaper than wire cut bricks Note: RE = Rammed earth
Fig. 62: Stabilised rammed earth Fig. 63: Stabilised rammed earth
Fig. 64: Composite plinth beam Fig. 65: Casting a composite plinth beam
Fig..66: Composite column 240 Fig. 67: Composite column 290
176 New Architecture and Urbanism: Development of Indian Traditions Composite Beams And Lintels
Reinforced cement concrete is cast in U shaped CSEB. The bottom part of the beam is precast in a reversed position on the ground. Once cured, it is lifted and the middle and top parts are built on it.
The blocks are used as lost shuttering, but they also help the compressive strength of the beam.
Vaulted Structures
The research on this kind of roofing aims to revive and integrate in the 21st century, the techniques used in past centuries and millennia, such as those developed in ancient Egypt or during the period of Gothic architecture in Europe.
Fig. 70: Triple height beam 240 Fig. 69: Double height beam 240
Fig. 71: 2 m span double height beam 295
1750 Kg/m, 5.54 mm deflection with cracks Fig. 72: 2.5 m span triple height beam 2401280 Kg/m, 4 mm deflection without cracks
Fig. 75: Bull eye 80 cm diameter, built in 2 days
Fig. 76: Catenary shaped vault 6 m
span, 3 m Rise Fig. 77: Starting a lunette Fig. 73: Typical sections of
composite beams
Fig. 74: “Egyptian shaped” catenary vault, 5 m span, 9 m long, built in 12 days
Sustainable Buildings 177 This R&D seeks to increase the span of the roof, decrease
its thickness, and create new shapes. Note that all vaults and domes are normally built with compressed stabilised earth blocks which are laid in “Free spanning” mode, meaning without formwork. This was previously called the Nubian technique, from Egypt, but the Auroville Earth Institute developed it and found new ways to build arches and vaults.
The free spanning technique allows courses to be laid horizontally, which presents certain advantages compared to the Nubian technique which has vertical courses.
Depending on the shape of vaults, the structures are built either with horizontal courses, vertical ones or a combination of both.
Fig. 78: Lunette, 1.2 span Fig. 79: Completed lunette Building a lunette 1.2 m span, 2.20 m rise, built in 3 days with 2 masons
Segmental vault, 10.35 m span, 2.20 m rise, 6 m long, built in 18 days with 4 masons
Fig. 80: Starting the squinch Fig. 81: Starting the segmental vault Fig. 82: Completed vault
Fig. 83: Horizontal courses Fig. 84: Laying keystones Fig. 85: Completed vault- Equilateral vault 3.60 m span, 8 m long, built in 36 days with 4 masons (raw construction)
178 New Architecture and Urbanism: Development of Indian Traditions
Fig. 87: Auram Blocks 245 Fig. 86: Auram Blocks 295
Fig. 88: Emergency House 1996 City Summit Habitat Istanbul, Turkey
Fig. 89: Prototype AUM House Assembled in 66 hours New Delhi,
India Fig. 90: Improved AUM House Assembled in 62 hours Khavda, Gujarat, India DISASTER RESISTANCE
Since 1995, research has been oriented towards the development of a cost-effective technology which is based on reinforced masonry with Hollow Interlocking Compressed Stabilised Earth Blocks (HI CSEB). Vertical and horizontal reinforced concrete members reinforce the masonry so as to create a box type system which can resist disasters.
Two types of blocks have been developed: the square hollow interlocking block 245, which allows building up to 2 storeys high, and the rectangular hollow interlocking block 295, which is used only for ground floors.
In June 1996, at the request of CRATerre and the United Nations (UNCHS/Habitat), the Auroville Earth Institute built a prototype demonstration house of 9 m2 – the
Minimum Emergency House, at Istanbul, Turkey, during the “1996 City Summit / HABITAT”. This house was precast in 10 days and assembled in 8 days.
Other demonstration houses of 23 m2 were built in India:
the Aum Houses. They were prefabricated at Auroville and transported up to New Delhi or Gujarat in trucks. The superstructure of the house was assembled in 66 hours by our 18-men team during the “1999 India International Trade Fair” at New Delhi. This demonstration was granted a gold medal by the India Trade Promotion Organisation for the excellence of the special display. The second demonstration house was built in Gujarat, after the 2001 earthquake, in 62 hours with a 20-man team.
This technology has been used extensively in Gujarat for the rehabilitation after the 2001 earthquake. With a six-month technical assistance from the Auroville Earth Institute, the Catholic Relief Services built 2698 houses and community centres in 39 villages. This technology was also transferred to Kutch Nav Nirman Abhiyan. This technology is presently
being used in Sri Lanka for the reconstruction of the zones affected by the 2004 tsunami.
Note that this technology has not been tested on a shaking table but it has government approvals, as it satisfies all seismic requirements:
- The Government of Gujarat, India, (GSDMA) as a suitable construction method for the rehabilitation of the zones affected by the 2001 earthquake in Kutch district. It is allowed to build up to 2 floors.
- The Government of Iran (Housing Research Centre) as a suitable construction method for the rehabilitation of the zones affected by the 2003 earthquake of Bam. It is allowed to build up to 3 floors (8 m high).
- The Government of Tamil Nadu, India, (Relief and Rehabilitation) as a suitable construction method for the rehabilitation of the zones affected by the 2004 tsunami of Indonesia.
Sustainable Buildings 179