Research paper - BAMBOO AS AN ALTERNATIVE TO STEEL IN RCC

Research paper - BAMBOO AS AN ALTERNATIVE TO STEEL IN RCC

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  USING BAMBOO TOREPLACE STEEL IN REINFORCED CEMENT CONCRETE STRUCTURES IN INDIA AVAILABILITY, CHARACTERISTICS AND COST COMPARISON Jaazim Salahudeen  Faculty of Architecture, Manipal University  11/23/2014
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   USING BAMBOOTO REPLACE STEEL IN REINFORCED CEMENT CONCRETE STRUCTURES IN INDIA  Page 1 USING BAMBOO TO REPLACE STEEL IN REINFORCED CEMENT CONCRETE STRUCTURES IN INDIA AVAILABILITY, CHARACTERISTICS AND COST COMPARISON Abstract This is a study done to evaluate the feasibility of using bamboo as reinforcement in RCC beam construction. The aim is to reduce the usage of steel. Focus is given on mechanical and physical properties of bamboo, durability and preservation methods, availability of bamboo in India and cost comparison. Methodology The study is done majorly as a literature survey on:  Physical and mechanical properties of bamboo  Durability of bamboo and preservation techniques  The embodied energy of different materials The cost of making one cubic metre of concrete is calculated for both steel reinforcement and bamboo reinforcement. Results are tabulated and analysed. Bamboo Bamboo belongs to the botanical family of grasses and is resistant to tensile stress and is therefore one of nature’s versatile products. In its ability to withstand tensile forces, bamboo is superior to timber and even to reinforcement steel (Griebel, 2013). Depending on the species, bamboo can be harvested in one to five years versus 10-50 years for most softwoods and hardwoods. Thereafter harvests are possible every second year for up to one hundred and twenty years the yield is up to 25 times higher than that of timber. Bamboo absorbs carbon dioxide and releases 35% more oxygen into the atmosphere than an equivalent stand of hardwood trees. Some species of bamboo grow more than three feet each day. It is one of the fastest growing plants. When it is harvested, it will grow a new shoot from its extensive root system with no need for additional planting or cultivation (Kappagantula & Lingam, 2007). Bamboo diversity in India India is the second richest country in bamboo genetic resources after China. These two countries together have more than half the total bamboo resources globally. Sharma (1987) reported 136 species of bamboos occurring in India. Fifty-eight species of bamboo belonging to 10 genera are distributed in the north eastern states alone. The forest area, over which bamboo occurs in India, on a conservative estimate, is 9.57 million hectares, which constitutes about 12.8% of the total area under forests (Bahadur and Verma 1980). On average, 250 air-dried culms weigh one tonne and the price per tonne of dry bamboo is approximately Rs 1000 (Katwal, et al., 2003)
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   USING BAMBOOTO REPLACE STEEL IN REINFORCED CEMENT CONCRETE STRUCTURES IN INDIA  Page 2 Table 1:Area under bamboo in India States/Union territories(year of inventory) Bamboo area (km2 ) Andhra Pradesh (1968-74) 6598 Arunachal Pradesh (1985-90) 4590 Assam (1988-90) 8213 Bihar (1971-74) 795 Goa, Daman & Diu 249 Gujarat (1977-78) 2806 Haryana 42 Himachal Pradesh (1974-76) 60 Jammu & Kashmir 15 Karnataka (1983-94) 4925 Kerala 517 Madhya Pradesh (1970-86) 18124 Maharashtra 8893 Manipur (1986-88) 3692 Meghalaya (1986-88) 3102 Mizoram (1988-89) 9210 Nagaland (1984-87) 758 Orissa (1976-84) 7822 Punjab 50 Rajasthan (1984-86) 529 Tamil Nadu 3101 Tripura (1989-90) 939 Uttar Pradesh (1981-85) 2010 West Bengal 1751 Andaman & Nicobar Islands 784 Total 89575 The largest bamboo covered area belongs to Madhya Pradhesh followed by Mizoram, Assam, Orissa and Andhra Pradesh. But when we compare the total forest area in each of these states we can see that Mizoram is far ahead with more than half its forest area as bamboo growth. Among the south Indian states, Andhra Pradesh has the largest bamboo cover, closely followed by Karnataka. Physical and mechanical properties Natural materials like wood and bamboo have varying properties from specimen to specimen depending on different factors like environment conditions, soil conditions, water content etc. So while designing for bamboo reinforcement the allowable stress is much lower than the failure stress compared to steel. Steel is a well tested material. Its properties are definite. Allowable stress of steel is taken much closer to the failure stress. In case of an unexpected situation, a bamboo structure can take stresses much more than what it is actually designed for. So a structure made of bamboo has better chances of surviving a natural disaster compared to steel. (Janssen 2000) Properties of bamboo depend on chemical composition, which vary with age, height and layer. Maximum strength is generally found in bamboo culms of around three to four years old. Embodied energy Bamboo can be considered as a low embodied energy material due to various reasons (Imbulana, et al. 2013).  It can be processed easily – labour consumption and machine usage is minimum Treatments for durability (for example boron treatment) are also not complex.  Wider availability makes it easy to find nearer to the construction sites. Hence the energy for transportation is low. We can see that bamboo has a very low embodied energy of 1.5 MJ/kg compared to Aluminium (155 MJ/kg), Steel (20.1 MJ/kg) and Timber (10 MJ/kg) Source: (Katwal, et al. 2003)
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   USING BAMBOOTO REPLACE STEEL IN REINFORCED CEMENT CONCRETE STRUCTURES IN INDIA  Page 3 Figure 1: Embodied energy for building materials Durability Without protective treatment, most bamboo species have an average durability of less than 2 years. But if it is covered and stored properly, untreated bamboo may last four to seven years. The lower portion of the bamboo culm is considered more durable, while the inner part deteriorates faster than the outer portion. The large amount of starch present in bamboo makes it attractive to mould, fungi, termites and beetles. The damage caused is maximum during drying, storage and subsequent use. Bamboo is more prone to soft rot and white rot attack than to brown rot. Bamboo consists of 50-70% hemicellulose, 30% pentosans, and 20-25% lignin. Bamboo is also known to be rich in silica (0.5 to 4%), but the entire silica is located in the outer layer (1mm), with hardly any silica in the rest of the wall. Bamboos also have minor amounts of waxes, resins and tannins, but none of these have enough toxicity to improve its natural durability. (Guadua Bamboo S.A. 2013) The innermost layers are more vulnerable to fungal and insect attacks. The typical lifetime of an untreated bamboo culm varies from one month to three years depending on the species and climatic condition (Li 2004) . For structural uses, whether for indoor or outdoor, whether in tropical or temperate region, bamboo should be treated with preservative chemicals to provide adequate service life (Gnanaharan 2000). Bamboo preservation methods The selection of the appropriate treatment method depends on various factors: (Guadua Bamboo S.A. 2013) 1. Condition of bamboo- dry or green 2. Form - round bamboo or splits 3. Intended use 4. Quantity and time available 5. Potential cause of decay Leaching of bamboo Immersing bamboo in water is known as leaching. It is a traditional bamboo preservation method used in certain Asian and Latin American regions. Bamboo from hilly regions was transported downhill by means of rivers in the form of rafts. By the time it reaches the destination, the leaching process would have been done. The starch content of the poles is subjected to a leaching process that tends to decrease the starch level and increases its durability. But leaching alone does not guarantee long protection but it does help to remove starch and enhances permeability for further treatment (Guadua Bamboo S A 2013). Chemical preservation Chemical preservation (with or without the help of special equipment) ensures long term protection. Depending upon the method of bamboo treatment, chemical preservatives can impart short term or long term protection. Most of the chemical used for treatment are toxic. Great care needs to be taken to meet performance, environment requirements and safety. Depending upon the carrier solvents, bamboo preservatives are divided into two different categories: Non-fixing and fixing type preservatives. Non-fixing preservatives will leach out the bamboo when exposed to rain. In other
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   USING BAMBOOTO REPLACE STEEL IN REINFORCED CEMENT CONCRETE STRUCTURES IN INDIA  Page 4 words non-fixing type preservatives are not suited for outdoor use (Guadua Bamboo S A 2013). The main examples for chemical preservatives are Boric acid borax (non-toxic), Copper chrome arsenic, copper chrome boron, Zinc chrome and Copper chrome acetic. Cost analysis Table 2: Cost comparison for one cubic metre bamboo reinforced and steel reinforced cement concrete beam The cost required for one cubic meter of concrete is calculated in the two different cases. Apart from the material cost for cement, sand, aggregate and reinforcement, the cost for labor and equipment is also considered. It was found that the major expense in a steel reinforced cement beam is from the steel. Structural steel reinforcement comes upto 157 kg for one cubic metre for concrete which cost about Rs. 9420 for the material alone. The quantity of bamboo reinforcement required for a similar RCC beam will be around 14 kg only. And the cost for the reinforcement, including the preservation and transportation comes to around Rs 10. Hence the total cost for a bamboo reinforced cement concrete beam is calculated as Rs.5371. Compared to the Rs 16944 of steel reinforced concrete we can easily understand the cost savings in using bamboo reinforcement. Figure 2: Cost comparison of bamboo reinforced and steel reinforced concrete beam The major difference in cost is clearly from the savings due to replacing steel with bamboo reinforcement. So from the above calculations it is evident that a bamboo reinforced cement concrete beam costs only roughly about 32% that of a steel reinforced concrete beam. That is a remarkable reduction while considering today’s housing shortage and rising housing prices. ITEM Steel Bamboo Cement Bags 2420.75 2420.00 Sand 378.00 378.00 Aggregate 588.00 588.00 Reinforcement 9420.00 10.00 Mason 111.00 111.00 Labour 700.00 700.00 Water carrier 278.00 278.00 Bar Bender 314.00 0.00 Mixer operator 14.28 14.28 Mixer Vibrator 14.28 14.28 Water Charges 1.5% 213.57 67.70 Sundries (including mixer machine, transportation etc) 7.5 % 1067.87 338.52 Contractor's Profit 10% 1423.83 451.36 TOTAL 16,944 5,371
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   USING BAMBOOTO REPLACE STEEL IN REINFORCED CEMENT CONCRETE STRUCTURES IN INDIA  Page 5 Conclusion From the literature studies it is evident that Bamboo is an abundant material in certain parts of India. Most of the species of Bamboo have proven its worth as a structural material. Specific studies and literature referred shows how structural members can be designed with bamboo reinforcement exactly like steel reinforced concrete members. The cost analysis further emphasis its feasibility to be used in construction. This study is expected to be a catalyst for further probes into the world of sustainable building materials. The replacement of steel is a huge leap forward for this end. Further studies can be done for using bamboo planks for walls, bamboo poles and tiles for roofing etc. List of figures Figure 1: Embodied energy for building materials ..................................................................................................3 Figure 2: Cost comparison of bamboo reinforced and steel reinforced concrete beam..........................4 List of tables Table 1:Area under bamboo in India.........................2 Table 2Cost comparison for one cubic metre bamboo reinforced and steel reinforced cement concrete beam....................................................................4 References 1. Gnanaharan, R., 2000. Preservative treatment methods for bamboo : A reveiw; part-II of Bamboo shelter : a demonstration of best construction practice, s.l.: Kerala Forest Research Institute. 2. Griebel, D. D., 2013. Advanced Fibre Composite Materials. [Online] Available at: http://www.futurecities.ethz.ch/project/b amboo/ [Accessed 30 September 2014]. 3. Guadua Bamboo S A, 2013. Chemical Bamboo Preservation. [Online] Available at: http://www.guaduabamboo.com/blog/ch emical-bamboo-preservation [Accessed 7 November 2014]. 4. Guadua Bamboo S A, 2013. Leaching Bamboo. [Online] Available at: http://www.guaduabamboo.com/blog/le aching-bamboo [Accessed 7 November 2014]. 5. Guadua Bamboo S.A., 2013. Bamboo Preservation and Treatment. [Online] Available at: http://www.guaduabamboo.com/bambo o-preservation/ [Accessed 7 November 2014]. 6. Imbulana, P. K. et al., 2013. Bamboo as a low costand green alternative for reinforcement in light weight concrete. SAITM Research Symposium on Engineering Advancements, pp. 166-172. 7. Janssen, J. J., 2000. Designing and Building with Bamboo, Eindhoven: International Network for Bamboo and Rattan 2000. 8. Kappagantula, A. & Lingam, P., 2007. Bamboo house India. [Online] Available at: http://www.bamboohouseindia.org/bam boo.asp [Accessed 15 October 2014]. 9. Katwal, R. P. S., Srivastva, R. K., Kumar, S. & Jeeva, V., 2003. State of Forest Genetic
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   USING BAMBOOTO REPLACE STEEL IN REINFORCED CEMENT CONCRETE STRUCTURES IN INDIA  Page 6 Resources. Kuala Lumpur, Asia Pacific Association of Forestry Research Institutions (APAFRI) and the International Plant Genetic Resources . 10. Li, X., 2004. Physical, chemical, and mechanical properties of bamboo and its utilization potential for fiberboard manufacturing, s.l.: s.n.