APPLICATION OF NATURAL FIBERS FOR REDUCING CARBON FOOTPRINT IN ROAD CONSTRUCTION

Transcription

1 INDIAN GEOTECHNICAL CONFERENCE APPLICATION OF NATURAL FIBERS FOR REDUCING CARBON FOOTPRINT IN ROAD CONSTRUCTION J.Maity1, B.C.Chattopadhyay2, S.P.Mukherjee3 ABSTRACT The global demand for reduction of energy consumption and mitigation of emissions of greenhouse gases like CO2 from development works, is big challenge for all nations. Carbon is the essential ingredient of all fossil fuels. When these fuels are burned to provide energy, carbon dioxide (CO2), a Green house gas (GHG), is released to the Earth s atmosphere. As material developments are becoming more dependent on carbon-based fuels, a rapid increase in the atmospheric concentration of CO2 has occurred. If current trend of fossil fuel use continues, the concentration of CO2 is likely to achieve harmful situation in future. According to experts, this could lead to global warming which may results in more frequent severe weather conditions and damage to many natural ecosystems. To avoid such disastrous situation many believe that it is essential to promote actions that ensure stabilization of atmospheric CO2 concentrations to safe limit. In 2004, CO2 reportedly constituted approximately 77% of total anthropogenic GHG emissions. The comparison of different GHGs in terms of their expected contribution to global warming within the next century (Climate Change The UK Programme 2006) is shown in Fig.1 70% 60% 50% 40% 30% 20% 10% 0% Carbon Dioxide Methane Nitrous Oxides Others Fig.1: Emissions of GHGs contributed to Global Warming within the next century (Climate Change The UK Programme 2006) 1 Maity_J, Civil Engg. Dept, MSIT, Kolkata, India, joymaity1975@yahoo.co.in. Chattopadhyay_B.C., Civil Engg. Dept, MSIT, Kolkata, India, ccbikash@yahoo.com. 3 Mukherjee_S.P., Civil Engg. Dept, J.U, Kolkata, India, sibapmukh@yahoo.co.in. 2

2 J.Maity, B.C.Chattopadhyay & S.P.Mukherjee Contribution of the road construction industry to global warming is well attested and can no longer be ignored. In conventional way, construction of Road consumes energy during production of highway materials and components, during transportation of materials from production plants to the actual construction of the road, and during demolition process of roads. Recently, in India large amount of construction of rural roads are going on under different schemes like, Pradhan Mantri Gram Sadak Yojona. Such constructions of road require massive quantity of good brickbats for sub-base construction in conventional way. But the production of bricks needs soils of special quality which are generally being procured mostly from agricultural lands which itself is of limited amount in India to be spared because of huge population and low per capita land holding. Further use of agricultural land for brick making inanely invites sociological problems. Again for burning bricks, large energy is consumed. But in India, conservation of energy is of highest priority. In view of this, there is great demand of using some alternate suitable materials in place of brickbats. As one of the important alternate materials for use in above case, sand is being advocated and is being thought to be capable of generating comparable California Bearing Ratio for ideal subbase. The natural fibers like Coir, Jute, etc. are eco-friendly and available in abundance in many countries like India and can be used as additive material in the sub base course employing sand to result increase in strength and decrease deformability. Natural fiber composites are also claimed to offer environmental advantages such as reduced dependence on non-renewable energy/material sources, lower pollutant emissions, lower greenhouse gas emissions, enhanced energy recovery, and end of life biodegradability of components. Since, such superior environmental performance is an important driver of increased future use of natural fiber composites, a thorough comprehensive analysis of the relative environ-mental impacts of natural fiber composites and conventional composites, covering the entire life cycle, is warranted. In this paper, comparative results of the estimated cumulative CO2 emission as well as cumulative energy embedded using possible alternate materials for subbase are highlighted. Advantages of the application of sand mixed with randomly distributed Coir fiber replacing conventionally used brick bats and jhama for sub-base road construction are presented. Keywords: Greenhouse gas, Global warming, Conservation of energy, Eco-friendly, Randomly distributed Coir fiber.

3 INDIAN GEOTECHNICAL CONFERENCE APPLICATION OF NATURAL FIBERS FOR REDUCING CARBON FOOTPRINT IN ROAD CONSTRUCTION J.Maity, Assistant Professor, Civil Engg. Dept, MSIT, Kolkata -150, B.C.Chattopadhyay, Professor, Civil Engg. Dept, MSIT, Kolkata -150, S.P.Mukherjee, Professor, Civil Engg. Dept, J.U, Kolkata -32, ABSTRACT Large amount of construction of rural roads are going in India which involve massive quantity of good brickbats for sub-base construction in conventional way. For burning bricks, large energy is consumed, but conservation of energy is of highest priority. So, there is great demand of using some alternate suitable materials in place of brickbats. The natural fiber is eco-friendly, cost effective and available in abundance in India and can be used as additive with sand to result increase in strength and decrease deformability. Apart from reducing the cost of construction, they also play a great role in reduction of CO2 emission and consequently help in the protection of the environment. Comparative analysis of CO2 emission as well as energy embedded using the application of sand mixed with randomly distributed Coir fiber for sub-base road construction are presented in this paper. INTRODUCTION For development of a country, large scale construction activities are unavoidable but such construction-related activities account for quite a good amount of CO2 emissions. In almost every sector, like coal, oil, gas, power generation, transport, agriculture, industrial production and residential construction, stress has been imparted on increasing energy efficiency and conservation. It is felt that reduction in consumption in various fields and rationalization of uses of energyguzzling systems would also substantially contribute to our country s efforts in reducing GHGs and mitigating global warming [1]. Contribution of the road construction industry to global warming can no longer be ignored. Construction of Road in conventional way, consume energy in a number of ways. Energy consumption in road construction occurs in five phases. The first phase corresponds to the manufacturing of highway materials and components, which is termed as embodied energy. The second and third phases correspond to the energy used to transport materials from production plants to the road construction site and the energy used in the actual construction of the road, which is respectively referred to as grey energy and induced energy. Fourthly, energy is consumed at the operational phase, which corresponds to the running of the road when it is occupied. Finally, energy is consumed in the demolition process of roads as well as in the recycling of their parts, when this is promoted. The cost-effective and alternate construction technologies, which apart from reducing cost of construction by reduction of quantity of road material by using alternate lowenergy consuming materials, can play a great role in reduction of CO2 emission and thus help in the protection of the environment. Conventionally brick bats are used in construction of sub-base of flexible roads. Due to large scale increase of construction of roads, particularly rural roads under Pradhan Mantri Gram Sadak yojona, in India, amount of bricks needed to meet the demand generated for brick bats, is of enormous quantity. Production of bricks needs soils of special quality which are generally being procured mostly from agricultural lands which itself is of limited amount in India to be spared because of huge population and low per capita land holding. Further use of agricultural land for brick making inanely invites sociological problems. Again for

4 J.Maity, B.C.Chattopadhyay & S.P.Mukherjee burning bricks, large energy is consumed. But in India, conservation of energy is of highest priority. In view of this, there is great demand of using some alternate suitable materials in place of brickbats. As one of the important alternate materials for use in above case, sand is being advocated [2] and is being thought to be capable of generating comparable California Bearing Ratio for ideal subbase. Moreover, geo-natural fibers like Coir which is eco-friendly, available in abundance in many countries including India and cropped each year, can be used as additive material in the sub base course employing sand to result increase in strength and decrease deformability. Such application will also reduce the cost of pavement. Natural fiber composites are also claimed to offer environmental advantages such as reduced dependence on non-renewable energy/material sources, lower pollutant emissions, lower greenhouse gas emissions, enhanced energy recovery, and end of life biodegradability of components. Since, such superior environmental performance is an important driver of increased future use of natural fiber composites, a thorough comprehensive analysis of the relative environmental impacts of natural fiber composites and conventional composites, covering the entire life cycle, is warranted. In this paper, comparative results of the estimated cumulative CO2 emission as well as cumulative energy embedded using possible alternate materials for subbase are highlighted. Advantages of the application of sand mixed with randomly distributed Coir fiber replacing conventionally used brick bats and jhama for sub-base road construction are presented. METHODOLOGY In a previous study [3-6] to investigate the effect of inclusion of natural fibers on CBR values of various locally available sands, the CBR tests were conducted for above three different types of sand mixed with various percentage of the Jute and Coir fiber by weight of different length of fiber in Unsoaked condition at corresponding optimum moisture contents. All the tests were conducted as per relevant I.S. codal provision [7]. From these experiments, it was evident that there is a significant increase in the CBR value for such sands when discrete natural fibers were mixed randomly in those sands. CBR value is found to be maximum for fiber length of 5mm for all natural fibers used. Optimum percentages of fiber inclusion for coir fiber were 1.5% of the dry weight of Fine and Silver sand. But for medium sand highest CBR value can be obtain for 1% of fiber inclusion [5, 6]. In this experimental study, coir fibers with varying percentage were mixed with sand causing maximum CBR. With optimum length of 5mm and optimum percentage of coir fiber of 1.5% of the dry weight of Fine and Silver sand, the fibers were randomly mixed with three different types of sand for different combination of mix at their corresponding OMC. ECOLOGICAL ANALYSIS AND DISCUSSIONS A typical PMGSY road section recently proposed to be constructed in South 24 Paraganas, W.B. is considered. The pavement composition of the road section as per IRC SP 72:2007, according to CBR value and Traffic are as: GSB-I 4.05m width and 150mm thick, GSB-II 3.75m width and 75mm thick, 3.75m width and 75mm thick, 3.75m width and 75mm thick, Premix carpet 25mm thick and Seal coat (B type) 6mm thick. Ecological advantages of the application of sand mixed with randomly distributed Coir fiber replacing conventionally used brick bats and jhama for sub-base road construction are analyzed as below: A) Calculation of Carbon foot print of the construction of road: In view to calculate the carbon foot print during construction, analysis was made for the production of CO2 per units of different items of road construction. Then the cumulative CO2 demand was estimated for subbase when constructional materials and possible alternate materials were used for construction of the subbase. From such analysis, the CO2 Emission (Tonnes) per km as well as percentage reduction of the same replacing conventionally used brick bats and jhama

5 INDIAN GEOTECHNICAL CONFERENCE in sub-base by laterite metal and sand, moorum and sand, sand mixed with randomly distributed polypropelene fiber and sand mixed with randomly distributed Coir fiber are given in the Table 1 and 2. The percentage reduction of CO2 emission per km by using randomly distributed Coir fiber and sand in sub-base is 62.05%. To calculate the carbon foot print during construction, the production of CO2 per units of different items of road construction was analyzed. Then the cumulative CO2 demand for different materials used in sub-base was estimated. Comparison of the total amount of CO2 emission (M.T.) for different materials used in sub-base is also shown in Fig. 1. From the figure, it is seen that by using randomly distributed Coir fiber and sand in sub-base considerable amount of carbon-di-oxide emission are reduced with respect to using other possible alternate materials. CO2(M.T.) COMPARISON OF PAVEMENT USING DIFFERENT MATERIALS IN GSB Geosynthetic Sand Laterite Sand Table 1: Comparative CO2 Emission analysis of different items of pavement using different subbase material. Description Carbon-di-oxide Emission (M.T.) Bats Coir Mooru Later Geosyn m ite thetic Jha Sand Sand Sand Sand ma Earth work & Subgrade Base I Base II Hard Shoulder Premix Carpet Total = Table 2: Comparative CO2 emission estimated for using different subbase materials Materials used in GSB Bats Jhama Coir Sand Moorum Sand Laterite Sand Geosynthetic Sand CO2 Emission (T) per km % Reduction in CO2 emission Nil MoorumSand CoirSand BatsJhama Fig.1. Comparison of CO2 emission of different material. The percentage of Carbon-di-oxide emission of different items of pavement using coir-sand in GSB is given in Fig. 2. PERCENTAGE CO2 OF DIFFERENT ITEMS OF PAVEMENT USING COIR-SAND IN GSB Open-Graded Earth w ork Premix Carpet 5% 2% GSB-I (sand coir) 7% GSB-I (sand coir) 9% Hard Shoulder 15% Fig.2. Percentage Carbon-di-oxide emission of different items of pavement using coir-sand in GSB. From figure, it is seen that by using randomly distributed Coir fiber and sand in sub-base considerable amount of carbon-di-oxide emission are reduced with respect to using brick bats and

6 J.Maity, B.C.Chattopadhyay & S.P.Mukherjee jhama (more than 62% per km) in GSB. The percentage of Carbon-di-oxide emission using coirsand composites in GSB of different works like compaction of road, material preparation and carriage of materials is shown in Fig.3. PERCENTAGE CO2 OF DIFFERENT ITEMS OF WORKS USING COIRSAND IN GSB CO2 FOR Compaction of road 3% for construction of the subbase. The Energy embeded per km as well as percentage reduction of the same replacing brick bats in sub-base by laterite metal and sand, moorum and sand, sand mixed with randomly distributed polypropelene fiber or Coir fiber are given in the Table 3 and 4. Table 4: Comparative estimation of Embedded Energy for using different subbase materials Materials used in GSB CO2 for Material Preperation 70% CO2 FOR Carriage Material 12% Fig.3. Percentage of Carbon-di-oxide emission of different works using coir-sand composites in GSB. Bats Jhama Coir Sand Moorum Sand Laterite Sand Geosynthetic Sand Energy Embeded (GJ) per km % Reduction in Energy embedded Nil The percentage reduction of energy embedded per Table 3: Comparative Energy embedded analysis of km by using randomly distributed Coir fiber and different items of pavement using different sub-base sand in sub-base is 62.21%. To calculate the energy embedded during material. construction, the production of energy per units of Embodied Energy (GJ) Description Bats Coir Moorum Laterite Geosynthetidifferent items of road construction was analyzed. Jhama Sand Sand Sand c Sand Then the cumulative energy demand for different Earth work & materials used in sub-base was estimated. Subgrade Comparison of total amount of Energy embedded for different materials used in sub-base are also Base I shown in Fig Premix Carpet Total = Base II Hard Shoulder 6105 ENERGY EMBEDED (GJ) FORCOMPARISON OF PAVEMENT USING DIFFERENT MATERIALS IN GSB Geosynthetic Sand Laterite Sand MoorumSand CoirSand BatsJhama B) Calculation of Embedded energy of the construction of road: In view to calculate the energy embedded during Fig.4. Energy embedded comparison of different material construction, analysis was made for the production of energy per units of different items of road construction. Then the cumulative energy demand From the figure, it is seen that by using randomly was estimated for subbase when constructional distributed Coir fiber and sand in sub-base materials and possible alternate materials were used considerable amount of energy embedded are

7 INDIAN GEOTECHNICAL CONFERENCE reduced with respect to using other possible alternate materials. The percentage of Energy embedded for different items of work using randomly distributed Coir and sand mix in sub-base layer is given in the Fig. 5. ENERGY EMBEDED FOR DIFFERENT ITEMS OF PAVEMENT USING COIRSAND IN GSB Open-Graded Premix Carpet 5% 2% Earth w ork GSB-I (sand coir) 7% GSB-I (sandcoir) 9% Hard Shoulder 15% Fig.5. CO2 emission of different items of pavement using Jute-sand From figure, it is seen that energy consumption for GSB layers (1) is much lesser in comparison to WBM layers (34%) though the thickness of GSB layers (225mm) is more than WBM layers (150mm). CONCLUSIONS From the study presented above, following conclusion may be drawn: 1. Randomly distributed natural Coir fiber and sand mix is more eco-friendly than artificial synthetic polypropelene fiber when used in subbase layer of road construction. 2. Randomly distributed Coir fiber mixed in locally available sand mix in construction of sub-base layer of road, decreases the carbon foot print as well as the embedded energy to a great extent. 3. Low cost natural Coir fiber can also be used in sub-grade to enhance its strength and CBR value. The improvement of CBR value reduces the design thickness of sub-base layers. This reduction will lead to not only large decrease in the cost of pavement construction but also in reduction of CO2 emission and embedded energy to large extent. 4. When natural Coir randomly mixed in sand is used in road construction of both sub-grade and sub-base will lead to very useful energy saving and reducing carbon footprint which is of utmost concern of all the nations on the globe. REFERENCES 1. Singh, V. and Prasad, H.S. (2004) Use of sand layer as subbase materials in road construction on alluvial soil, Proc. Indian Geotechnical Conference on Ground Engineering: Emerging Techniques, Warangal Vol 1, p Sengupta, N. (2008) Use of cost-effective construction technologies in India to mitigate climate change, Current Science, Vol. 94, no. 1, 10 January, Maity, J., Chattopadhyay, B.C. and Mukherjee, S.P. (2010); Application of geonaturals spoils in sub base for Road Construction Proc. Indian Geotechnical Conference, Vol.-I, Dec , 2010, Mumbai, pp Maity, J., Chattopadhyay, B.C. and Mukherjee, S.P. (2013), Improvement of Characteristics of Sand mixing with Natural Coir Fiber Indian Journal of Geosynthetics and Ground Improvement. Vol. 2, No.2, July pp Maity, J., Chattopadhyay, B.C. and Mukherjee, S.P. (2012), Behaviour of Different Types of Sand Randomly Mixing with Various Natural Fibers, Journal of The Institute of Engineers(India), Series A, May 2012, Vol-93, Issue -2, pp Maity, J., Chattopadhyay, B.C. and Mukherjee, S.P. (2012), Behaviour of sands mixed randomly with natural fibers Electronics Journal of Geo-technical Engineering, Vol. 17,Bund L, pp BIS 2720 (Part XVI) -1987, Laboratory determination of California Bearing Ratio. Bureau of Indian Standards, New Delhi, India.