Assam is located in the north eastern part of the country, surrounded by six of the other seven sister states: Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura and Meghalaya. It is a land of plains, hills and river valleys.The North-Eastern region of India, being prone to many types of natural calamities, uses building construction techniques which prove to be resilient to disasters.
One of the most common types of traditional housing practices found in this part of the country is the Assam-type housing, predominantly witnessed in the state of Assam. This type of construction uses lightweight materials such as bamboo, ikra (a locally available reed), wood etc which prove to be extremely effective against earthquake events. Unfortunately these houses are becoming extinct with the advancement in technology, and hence the growing popularity of RCC multi-storied buildings and steel framed structures.
House Building Materials and Typologies:
Because Assam is an earthquake-prone region, a special type of earthquake-resistant a house is built. Bamboo, wood, thatches, cow dung, reed, cane, and other available local materials were used to construct Assam-style houses in the past. In traditional Assam-style houses, a weed called Ikora is extensively used to construct the walls and roof. The walls are also plastered with earth to make them stronger and more protective. Bamboo strips are sometimes used to make mud-plastered walls. Both bamboo and wood are used for the doors and windows. Mud plastered floors are common in rural areas. Local grass and thatch, as well as bamboo and wooden frames, are used to construct the slanting roof.
Modern homes, such as yours, can incorporate Ikra panels in parts of the houses, in conjunction with techniques suited to the modernity of the house. The unique textures that can be created using this method, certainly leads it to be a focal point.
Ikra is a popular method of construction in Assamese homes wherein reeds are used in conjunction with materials like mud or adobe for the construction of walls. It is not a practice of today; Ikora form of construction has been in practice for the past two hundred years or so.
Typically these houses are built with lightweight locally available materials like bamboo, wooden planks, thatch etc. Such houses have a proper system of bamboo/wooden beam-column and fulfil the earthquake safety requirements of rectangularity and simplicity. Ikora houses are single-storey structures consisting of brick or stone masonry walls up to about 1 m above the plinth.
This masonry supports the walls consisting of bamboo woven together with a wooden frame, and plastered with cement or mud plaster.For the construction process bamboo poles are used as the frame of the house with a shallow foundation. Once the bamboo columns are erected next is the construction of the walls. The Ikora are laid vertically and woven together into a form of a mat with thin pieces of bamboo. Next is the plastering of the walls for which mud mortar is used.
The mud mortar is prepared simply by mixing soil and water until the mixture becomes plastic enough to be laid over the Ikora walls. The walls are plastered on both sides with a decent number of coats of mortar. After the mortar has dried a finishing coat made from a mixture of mud and cow dung is applied over the walls.
There have been no reports of any significant damages to Ikra structures during past earthquakes.The need of the hour, hence, is to minimise destruction and mishap by providing lightweight renewable materials for the structure. Bamboo, is another locally abundant material and fits the bill undeniably.
Traditional houses are generally made of locally available materials and in this region bamboo is a material found in abundance. In a bamboo housing system, bamboo is used as the main structural members. The brick wall is used for modelling. And it is rigidly connected with plinth as well as with bamboo. In this system the wall is made of bamboo strips and it is plastered with mud.
Now, for any kind of house the frame of the building is very crucial as it takes up the load applied and transfers it to the ground below. For houses built in earthquake prone areas an added parameter of flexibility of the frame along with load carrying capacity is needed, because rigid structures when vigorously shaken by an earthquake break more easily as compared to structures which are flexible.
This is where the humble bamboo steps in. Bamboo has been known since ages to be a flexible yet strong material having the capacity to take up dead, imposed and as well as seismic loads. The cheap and easy availability of bamboo made it a popular building material among the masses. Moreover in seismic zones the building materials used are supposed to be lightweight so that if during an earthquake any of the members break and fall they don’t cause fatal accidents. Apart from the lightweight materials used, earthquake resistant construction practices such as use of seismic bands at the roof, lintel and plinth level make these houses safer.
The houses are detailed out to combat the heavy monsoons. The roof of the house is built of local grass and can last up to 10 years before it is replaced again.
Mahi, a unique herbal ink prepared with cow urine as extractant, was used for manuscript writing in early Assam.The key factor for this long-lasting marriage between Mahi and Sancipat (folios made of bark of the sanci tree) is the herbal concoction’s resistance to aerial oxidation and fungal attacks and its non-corrosiveness. It was also non-corrosive unlike the corrosive acidic iron gall ink (IGI) of contemporary Europe.
A cocktail of fruit pulp and barks such as haritaki, amla, bibhitakhi or bhomora, mango, jamun, often infused with the blood of eels or catfish. Mahi was extracted using cow urine. Rust from iron tools or nails were also added for an intense black hue. Mahi’s endurance is proven by the stability of Sancipat manuscripts that are said to have existed for centuries without fading or wearing out.
The major phytochemical constituents in Mahi have been identified as phenolic acids, flavonoids and tannins and their complexes with iron. Though there are several recorded recipes for Mahi formulation, one commonality exists for all, the season during which it is concocted.It is only prepared (in natural settings) in the winter season. The low temperatures and dry conditions in winter ensure minimum exposure of the mixture to microbes and heat, which may decompose the dyes during the long time needed for extraction. Another interesting feature is that the pH of Mahi remains neutral because of cow urine and the absence of acidic ingredients like vinegar.