SPATIAL EXPERIMENTS IN FERROCRETE




 


Ar. Shekhar Garud graduated from School of Planning and Architecture,  New Delhi in 1984. He is partner in the firm Narendra Dengle and Associates and currently teaches at VIT’s PVP College of Architecture, Pune. He has been actively associated with IIA, AESA,BAI,PCERF.


Ferrocement is commonly known to be a mixture of Portland cement and sand applied over layers of woven or expanded steel mesh and closely spaced small diameter steel rebars. Being able to be formed into relatively thin, curved sheets, it is extensively used to form hulls for boats, shell roofs, water tanks, sculptures, prefabricated building components etc.
A Frenchman, Joseph Monier ( 1823-1906) invented “Ciement arme”. As a gardener, not satisfied with clay pots which are easily broken, he experimented with embedding iron mesh in cement and sand mixture and invented ferrocrete troughs and later on even took patents for iron-reinforced cement pipes, cement panels for building facades and other reinforced concrete products. Paris exposition of 1867, brought the attention of the world on his products and patents and reinforced concrete started becoming a prominent building material.
Another French inventor, Joseph-Louis Lambot (1814-1887) was also simultaneously working laong the same lines who first constructed a boat in reinforced cement concrete and exhibited at Exposition Universelle at Paris in 1855.
In 1875, Monier expanded his patents to include even bridges and designed his first steel and concrete bridge. He also introduced “Faux Bois” concrete in which the outer layer was sculpted to mimic rustic logs and timbers.
Ferrocrete, with relatively good strength, resistance to impact , better resistance to fire, earthquake and corrosion than traditional methods such as wood, adobe and stone masonary, has become quite a popular material not only in construction but also creating “novelty architecture”. It has become popular because the technique can be learned very quickly, thus people are able to supply their own labour and become active participants in the process.
Ferrocrete as a construction technique was made popular in India by a gifted structural engineer and alumnus of College of Engineering, Pune of 1948 batch, late shri Vishnu Joshi. While working with the renowned architect Joseph Alan Stein as structural engineer and designing structures for many landmark buildings like Express Towers at Mumbai, India International Centre and India Habitat Centre at New Delhi, he explored “Ferrocrete” as a material for innovative use. He believed “it was most suitable for developing countries, which could help in employability of unskilled labour.” It was his passion and commitment to the spread of knowledge that inspired a generation of architects, structural engineers as well as civil contractors to explore ferrocrete in innovative ways.  Apart from creating miscellaneous building components for use in building industry and irrigation projects, his vision inspired many to create fascinating building forms using ferrocrete.
As he settled in Pune in later part of his life, his vision and guidance inspired Ar. Narendra Dengle to design some fascinating roof forms which explore the freedom offered by ferrocrete, unmatched by ordinary reinforced cement concrete. While the architect skillfully explored the forms, the expertise and experience of late shri V.D. Joshi ensured the strength, stability and performance of the structure.
Architect’s own house and studio at Pune, constructed during 1995-1997 provided the first opportunity to explore the possibilities and the freedom offered by ferrocrete. For a house designed with minimal use of RCC and extensive
 use of load bearing construction in hollow concrete blocks, modulated roof forms in curved ferrocrete “in-situ” construction was the natural choice. With the use of plywood shuttering, bent to desired shape, interesting volumes could be created for the first floor rooms. Along with the “in-situ” ferrocrete roofing, pre-cast panels/petals were used to construct a truncated dome (Shankav) over the central double heighted family space. Even though, the volumes are large and complex, the structure itself is very light and Elegant.
The Welfare Centre for workers at Deccan Florabase, a floriculture project near Pune, executed during 1998-2001, consisted of tow overlapping octagons in plan. The roof was designed as a folded plate structure with a central skylight and covered by a thin ferrocrete skin. The skin was cast in-situ supported by “Sitatex” boards used as lost shuttering over a steel structure. China mosaic finish offered the waterproofing and acted as a thermal reflector.
During the same period, a guest house complex at Vansda, Gujrath was constructed for BAIF, Pune. Since BAIF had been actively promoting use of ferrocrete for constructing Toilets in remote villages by training the villagers, they readily accepted the pyramidal roof over the Canteen and sloping roofs for the guest rooms, both to be done in precast ferrocrete panels. The pyramidal roof with a skylight at top was conceived as an assemblage of easily manageable pre-cast ferrocrete plates which when could be joined together with cast-in-situ edge beams. Once the structure was complete, batons were cast in cement mortar for placing the manglore tiles over them. The guest rooms were also provided with pre-cast ferrocrete panels complete with eaves boards, finished in manglore tile roofing. This technique along with the exposed brick walls created a harmonious architecture in the rural setting. The pre-casting techniques saved lot of labour and it could be done under skilled supervision by unskilled workers. It also demonstrated a new economical and better performing technique of building sloping roofs compatible with the local architecture.
The “Universal Temple of Sri Ramakrishna” at Pune, built during 1998-2002, provided a unique opportunity to explore ferrocrete daringly for one of the most conspicuous elements of Indian temples, i.e. the shikhara. The architect has deviated from the practice of making the shikhara as a solid element with various types of adornment and created a lightweight, porous and transparent shikhara. Thus not only the association of the devotees with the traditional image of the temple is respected but an aesthetic experiment in using ferrocrete technology hs been successfully carried out. The petals of the dome were precast on the ground when the main structure was being built and then they were joined together progressively with cas-in-situ ribs. The petals of the smaller domes were also precast  and then assembled on site. Glass mosaic tiles have been applied over the exposed surfaces as a waterproofing and aesthetically pleasing finish. While the traditional shikaras are always lit up from outside, this unique shikhara “glows from within”. The precasting technique saved major construction time and simplified the construction itself.
All the above experiments which involved the imaginative architectural solutions supported by innate understanding of the structural aspects were guided by late shri V.D.Joshi. After his demise, the ferrocrete technology was nurtured by his disciples with equal passion. Ar. Dengle designed further  projects with Er. Bhalchandra Bhedasgaonkar who had been trained by late V.D. Joshi in the ferrocrete technology.

For the extension of Swami Samartha Math at Hedavi, built during 2007-09) a different attempt was made in the form of a asymmetrical pyramid over the existing garbhagirha. The roof is envisaged as a skin of asymmetrical stepped pyramid supported on sloping RCC beams. The stepped form was explored to create opening at various levels for admitting light and ventilation in the spaces below.
The proposed Railway Museum at Mysore, has been conceived as three interconnected vaults like a wavy tunnel under which the vintage collection of railway engines and bogies will be displayed. Here again the ferrocrete skin is wrapped over the steel structure of the vaults. The skin has a layer of thermocole sandwitched in between the ferrocrete skins. The structure would be light and the construction time for such a large volume would be less.
At present, the redevelopment of the Mhasoba Deosthan at village Kharawade near Pune is under construction which also has a shikhara over garbhagirha with precast petals assembled on site  with cast-in-situ ribs. The Sabhamandap will have a pyramidal stepped roof with in-situ ferrocrete skin with sandwitched thermorcole offering thermal insulation.
Ferrocrete does offer interesting possibilities in modulating the roof forms provided the structural engineer guides the architect in resolving the stability and strength issues. Adequate care and expert supervision to ensure quality and maintaining accuracy of the geometry is very critical. Ferrocrete is not only a material / technique to produce low cost building components but can be explored most imaginatively by architects and open minded structural engineers to create a different spatial experience.
 

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