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Let's Plant Bamboo-Guadua To Harvest Houses

Let's Plant Bamboo-Guadua To Harvest Houses


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By By Mario Francisco Alvarez Urueña *

There is definitely in guadua a great potential for solving many problems, especially housing and this without overlooking (especially with bamboo): food, production of ethanol -alcohol- cellulose -making of paper-carbon, medicinal uses , protective forests and many more.

Can you imagine that by sowing 80 guadua seedlings today in an area of ​​1,300 m2 -31.50 mts x 31.50 mts approx. - after 4 or 5 years you can "obtain in one go" a developed guadual, with the approximate corresponding material to 130 stems or culms required to build the walls and structure of upper beams and columns necessary for a house of 60 M2, besides that the guadual as a perennial crop is still productive.?

The above is perfectly possible not only in Colombia but also in most of the world, taking into account that in a native guadual, of the coffee zone type, technically exploited we can obtain 1,300 culms or guadua stems per hectare / year; or if it is a new crop, we can begin to exploit it intensively from the fifth (5) year of sowing; which means obtaining the basic material to build 10 houses / year that according to the policies, priorities and needs in the housing solution we can adjust the area of ​​cultivation and exploitation; this without taking into account existing crops.

There is definitely in guadua a great potential for solving many problems, especially housing and this without overlooking (especially with bamboo): food, production of ethanol -alcohol- cellulose -making of paper-carbon, medicinal uses , protective forests, carbon "sink", erosion control, landscaping and many more, we find in this a resource little exploited and known in our environment in a technical and massive way. Unfortunately, we have known guadua in temporary and poorly made constructions (temporary construction camps, "slum" houses), which has led to a certain loss of prestige; But in the same way as the house of the rich or the poor is built with brick, the same happens with this one and finally it is not the material itself that makes the difference but rather an integral conception that makes it. Its importance is evident from the "I World Congress of Bamboo / Guadua" -Pereira 1992- to the different forums and seminars on the subject and the recent "Symposium on the uses and services of Bamboo / Guadua" -Armenia 2001-. This writing is a contribution to the dissemination of a resource, of which there is very little scientific technical literature, guadua is a suitable material for many types of construction, especially social housing and which, paradoxically, more Germans and Dutch know, where not there is, that we ourselves where it grows wild. In the spirit of brevity, I omit in these notes aspects related to forestry, taxonomy, anatomical, among others -developed in my book-; additionally as a result of my own experiences and research and at the request of my readers of a past article on the internet: "From the House of Guadua to the House of Paper Tubes" who asked me for more information about it.

HOUSING DEFICIT IN COLOMBIA AND THE WORLD

According to calculations by "HABITAT", the housing needs of the world population will double by the middle of this century; there are particular cases like that of Africa, where it will triple. It is estimated that more than 600 million urban dwellers and more than 1 billion peasants from Asia, Africa and Latin America live in accommodation that is "so crowded and of such poor quality with such an inadequate provision of water and sanitation that their health and their lives are continually at risk "; the supply of accommodation is practically destitute. The United Nations - UN - estimates that at least 100 million people in the world do not have any home; the number reaches 1 billion if "those with especially unsafe and temporary accommodations, such as trespassers, are included" (Brown 1999); It is here where the beautiful, resistant and economic guadua becomes a true world alternative to satisfy the hunger for housing; additionally fulfilling a purpose of substituting the use of wood for another alternative construction material, economic and indicated for a region of high seismicity.

In Colombia, although it is difficult to determine the housing deficit due to strong internal and external migratory flows; According to a report by "CAMACOL from June 2001, which is based on the 1993 census, the current housing deficit in the country is concluded at a figure of over 1,400,000 units." At the end of the year 2,000, there were an estimated 6,180 in Colombia. 000 urban households and an average of 182,000 new households were created each year in the decade 1990-1999, of which 128,000 with incomes below 4 smlm. (at $ 1,040,424 corresponding to $ 495 USD)

FIRST THINGS FIRST: SOW GUADUA

Of the once immense native guaduales destroyed to expand the agricultural frontier, in Colombia, it is estimated that only 54,000 hectares remain today; For this reason, promoting its cultivation is the first priority and although it is a perennial crop, its importance lies in finding substitute materials for wood due to its high cost and the great deforestation suffered by the environment. The constructions with guadua have proven to be a safe system -see the report of the earthquake in Armenia, Colombia, of January 2000- above all, taking into account the high degree of seismicity faced by our country and Latin America in general. My specific proposal is to develop a guadua construction policy that begins by strengthening laboratories in the style of: Cordoba -Quindío, Colombia- for the cultivation of seedlings or "chusquines" -the most efficient form of propagation- whose dimensioning also to attend a reforestation policy (protective forest) also encourage its industrial exploitation which is our objective.

To sow one (1) hectare, approximately 625 seedlings / Ha are required. -if it were carried out in a planting grid of 4 X 4 meters. which depends on many factors- as a reference, the cost of sowing per hectare is estimated at $ 39,900 pesos / HA (USD $ 197) and for its management at $ 388,500 pesos / HA (USD $ 185) for a period of 5 years including the value of labor. Assuming that said propagation laboratory works continuously for a certain period, we will obtain the necessary material to achieve the planting goal and with such an area obtain the necessary material to sustainably build -from the fifth year- a certain number of houses per year, the above without taking into account the existing guaduales and their exploitation possibilities. Assuming that the average present value per mature stem in said plantation is around $ 1,500 pesos ($ 0.71 USD), which corresponds to the current value in the guadual; We will have that for the projected house of 60 M2 with 130 stems or culms, the cost of said basic input would be in the order of $ 195,000 Colombian pesos in December 2000 (92 USD $) to the above, we must add transportation and immunization and the rest Necessary materials and different from this, such as: the reinforced concrete foundation -similar to that of a conventional brick house- electrical, hydraulic and sanitary installations with their corresponding devices, panels, paint and cover.

VEGETABLE STEEL

One of the current problems regarding the physical-mechanical characteristics of guadua is that the documentation of said investigations is not approved; to have an order of magnitude and given the seriousness and representativeness of the tests carried out by the "German Institute for Testing of Civil Construction Materials in Stuttgart" in November 1999 for the ZERI pavilion in Colombia at ExpoHannover, in guadua variety "macana" from the coffee zone; We present their results noting that they do not correspond to the limits but to those of design: 1) Compression. Sigma: 18 N / mm2, Lamda: 0, Modulus of Elasticity: 18,400N / mm2 2) Tension. Sigma: 4 18 N / mm2, Modulus of Elasticity: 19,000 N / mm2 3) Bending: Sigma 18 N / mm2, Modulus of Elasticity: 17,900 N / mm2 4) Shear: Tau -without cement in the pipe- 1.1 N / mm2 5) Specific Weight: 790 Kg / M3. Conclusion -and comparatively- an iron rod with a section of 1 cm2 - less than ½ "- resists to traction 40 KN. (Kilo Newtons); a guadua with a section of 12 cm2 resists 216 KN. For this reason it is called : "vegetable steel"!
Let us remember that guadua works very well in flexion and traction, in the latter the problem is how to hold it efficiently; it works very badly when bending and crushing perpendicular to its length; therefore the guadua structures must be calculated as articulated bars in ties; since in none of these nodes can it be considered as a frame structure or an embedment.

SECOND: BUILDING WITH GUADUA

In Costa Rica in 1988 there were no guadua - there were other varieties of bamboo - and only 3-4 years after planting 2,000 houses were built in this material; the "National Bamboo Project" (PNB) decided to build 7,200 bamboo houses at low cost. In Bangladesh there are 15 million houses made of bamboo. By sowing guadua a variety of bamboo, we can harvest ecological houses with excellent earthquake-resistant characteristics due to their characteristic of light and very flexible "vegetable steel", a renewable natural resource that, unlike wood that is cut and must be re-sown; the guadua is not cut if not pruned; taxonomically, bamboos belong to the most primitive, diverse and least studied family of Poaceae (grasses), the so-called subfamily Bambusoideae; from where the variety of "Bambusa Angustifolia Kunth" or guadua is derived; a true dinosaur of the plant kingdom; It is not a forest species (tree), it is a grass, that is, a giant grass of the same family of corn, rice and wheat; it is the fastest growing plant species; it can grow an average of 10 cm per day; unlike timber trees that require about thirty (30) years for their exploitation and use in construction. Pine, which is one of the fastest growing forest species (tree), takes 15 years to be used; Guadua can be used after 4 years of sowing when it is mature and is suitable for use in construction.

It must be taken into account that the good design of a construction and its earthquake resistant properties are the product of the correct application of a series of design and construction principles, namely: 1. Regular shape. 2. Low weight. 3. Greater rigidity. 4. Good stability. 5. Firm ground and good foundation 6. Adequate structure 7. Competent materials. 8. Quality in construction 9. Capacity to dissipate energy and 9. Correct fixing of finishes and installations.

The horizontal forces that generate an earthquake are directly proportional to the mass or weight of the construction and its height or "center of gravity"; consequently, the higher the weight and height, in the event of an earthquake there is more acceleration and greater damage. Due to their low weight the constructions with guadua present an excellent behavior against these. Let's see some figures:

The weight of a wall of cement bahareque is between 90 and 130 Kg./M2; a hollow concrete block wall weighs 250 kg / m2 and if it were made of adobe it would be between 500 and 700 kg / m2. A wooden mezzanine weighs 70 to 90 Kg./M2 compared to one of joists and reinforced concrete slabs that weighs 400 Kg./M2, a galvanized tile roof (Zinc) weighs 20 Kg./M2 including the trusses; that of asbestos cement tiles weighs 30 Kg./M2 and if it were made of clay tile it would weigh 90 Kg./M2

Every year earthquakes and earthquakes confirm the lack of respect for good construction standards; "strong" material properties do not necessarily guarantee strong buildings, because bricks are inflexible and have a serious problem because of their high specific gravity. Modern earthquake-resistant buildings in Kobe, Japan, when the 1995 earthquake struck, were too rigid to withstand shock waves and failed. The bamboo or guadua canes on the other hand are very flexible. The January 2000 earthquake in the coffee region knocked down almost all the brick buildings, as well as different reinforced concrete structures and even some bahareque houses with rotten bases; although in general they responded quite well; Many studies were done to establish the physical mechanical properties of Guadua and they confirmed that the tensile strength is comparable to "vegetable steel"; the importance of protection by design, protection against all types of humidity, adequate anchoring and avoiding overly rigid triangulation was highlighted. The establishment of special construction standards with Guadua is also required and a law to be added to the current Earthquake Resistant Standard is close to presidential sanction in Colombia.

PLATES AND SCREWS

The current development of the system is based on the use of 3/8 "screws with their respective nuts and washers and the use of 7/8" x 1/8 "plates and clamps, all of them screwed and as guadua works poorly to crushing in the supports or crosses between them, this is supplemented by filling the pipes with cement mortar and sand 1: 3 or 1: 4.

As we see the correct concept of design and construction is essential, it is a matter of knowledge of specialists. If your construction is in guadua or in cemented guadua bahareque, do not add brick walls or heavy elements of the style that make it vulnerable to an earthquake. Remember that construction in guadua is characterized by being light and flexible, faithful to the Chinese principle that says that "bamboo that does not bend splits. Although it may seem incredible in the city of Armenia -the" Mecca "of guadua in Colombia- it find the ruins of a deplorable and recent experience of mismanagement and design in a small urbanization carried out by the same municipality where the most elementary principles of design and construction were ignored, resulting in the total deterioration and abandonment of said houses by of its inhabitants in less than three (3) years of being built; but there we also find, as in all of old Caldas, Tolima, Valle del Río Cauca and Antioquia, excellent examples of houses built a hundred years ago that are intact and that of more recent constructions very well designed, built and preserved in this material.

Building with bahareque cemented with guadua is at least 20% cheaper compared to traditional brick, iron and cement construction, and its durability is of many generations if the rules of its good use have been followed.

EMPLOYMENT GENERATION AND COMMUNITY ORGANIZATION

The constructions in this material do not require specialized tools and allow the intensive use of unskilled labor, although there must be a professional and a master craftsman in their direction; This contributes positively to job creation. We do not propose here the revalued self-construction system because it is uneconomical; We propose the design and construction with the participation of the community so that each individual contributes actively to the quality and definition of their own home and leads them to appreciate and re-evaluate the concept they have about this type of material, the above within the concept of Companies Community Construction. The experience of Costa Rica teaches us that the project has allowed the planning of a communal organization system, through housing committees in each of the communities, forming groups of beneficiaries who have received technical advice from the PNB. In many of the communities, the system contributed to their development, not only in terms of the construction of houses, but also in repairing roads, drinking water, improving their health conditions, and marketing agricultural products.

HISTORICAL AND CULTURAL ASPECTS OF THE BAHAREQUE.

In Colombia and Latin America, the architecture of the bahareque is the product of the fusion of elements contributed by the natives and colonizers that gave rise to a mestizo architecture: the bahareque, the adobe and to a lesser extent the tread wall, which in turn they constitute the most frequent ways of working with clay in our construction tradition. The tread wall and adobe were the European contribution of the colonizers and given the high seismicity in the coffee region, they were quickly abandoned due to their vulnerability to earthquakes. They all have a common ingredient: clay.

The bahareque is autochthonous and corresponds to the constructions that our natives made and it is their best legacy; The bahareque houses were built using the original covering of the interwoven structure of reeds, sticks and / or guaduas, it was a mixture of mud, straw and dung; a frame with pitchforks or guaduas nailed directly to the ground and tied by vines; By way of walls, a wall was armed with vertical or horizontal elements constituted by "cans" of guadua or thin wood, forming a kind of box which was filled and then a plaster or clay cloth was applied. The roof was made up of a main framework in thicker wood as beams and a secondary one with thinner rods or canes and covered in straw, which later evolved to zinc tile and baked clay tiles.

DECALOGUE OF THE GOOD MANAGEMENT OF GUADUA FOR CONSTRUCTION

Here is a brief summary of aspects more widely developed in my book:

1. Select and previously mark the guaduas to be cut. Use "jechas" or ripe guaduas of 4 or 5 years. Although this occurs from sea level to 2,600 meters above sea level, those that are found over 1,300 meters above sea level - coffee zone - have the best physical and mechanical characteristics.

2. Cut in the moon phase of "waning" between the hours of midnight and dawn.

3. Make the "bleeding" or "vinegar" on the plant; leaving them there packed vertically and protected from the ground for 20 to 30 days.

4. Clean and wash them with water and then allow them to dry naturally or artificially by scrunching them up very well to allow them to dry evenly and then leave them indoors until they turn yellow.

The previous steps correspond to the basic treatment that our ancestors practiced and that today allows us to have bahareque houses with more than 100 years of construction and in very good condition against the attack of pests.

5. Immunize it, preferably use natural products that are not harmful to man. "Pentaborate" is a good, proven, safe, inexpensive option that does not cause harm to man or the environment. Treatment by means of smoke widely used in Japan, although not technically experienced in our environment, is an excellent option. Immunization "under vacuum" is very good, although the most expensive, and it goes without saying that there is a wide range of chemical products from different laboratories for its preservation, some that are worth more than the same guadua and others that threaten human health. In "organic" agriculture there is a wide range of natural immunizers to investigate.

6. The guadua must be protected from the elements (sun and water) and duly protected from humidity by capillarity, therefore it must be placed under roof and protected with large eaves and good pedestals and / or baseboards above the floor, with a height A minimum of 40 cm to protect against the splashes of rain and water by capillarity, taking into account the principle of having "good boots and a good hat".

7. Do not use tiptoe, nailing the slit; drill holes using drill and use with washers and nuts. Make properly the ties between guaduas in "fish mouth" and the appropriate ones to tie cylinders. After 6 months of construction, retighten the nuts.

8. As a final finish and protection against the ultraviolet rays of the sun that discolor and damage it and as an insect repellent, an application based on linseed oil with turpentine, or bitumen. Do not use enamels, they do not let you breathe.

9. Do integral maintenance to the construction, preventing pests, dampness and deformations. Keep in mind the 5 enemies of guadua which you must solve and foresee in its design and construction:

1. Water, humidity and bad weather, which cause rot.
2. The fire that consumes it.
3. Fungi and insects, which attack its structure and destroy it.
4. The ultraviolet rays of sunlight that discolor it and make it more vulnerable to the above agents.
5. Bad design and bad construction that destroy it quickly.

Dear reader, I hope to leave you some good concerns about this material that will serve to promote its study, research and use. Many successes and to "Plant bamboo / Guadua to Harvest Houses" consistent with their knowledge, correct management, good design and excellent construction.

Ibagué, Colombia, July 2002

* Architect graduated from the "National University of Colombia". Bogota 1977.
Partner of the "Colombian Society of Architects". Professional activity: Design and Construction of Housing and Urbanizations especially of "social interest", as well as designs and constructions in guadua.
The above is a brief summary of my book on the subject; which is in development.
Phones: (57) (8) 2702125; (57) (8) 2699517; Cell: 03315 - 7923513
Ibagué. Colombia.
email: [email protected]


Video: HOW TO PROPAGATE BAMBOO (July 2022).


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