Innovative Materials Strategies To Solve Global Warming – The Use Of Bamboo Plastic Composites For Sustainable Building

The Need for Sustainable Building Materials

Title: Use Of Bamboo Plastic Composites For Sustainable Building.

The current practices of construction have led to a rapid consumption of energy and depletion of natural resources. The has been a problem of resources availability and their accessibility. The traditional building materials such as concrete and aggregate have been found to be using around 30-40% of global energy production, with this kind of energy use they account to around 30% of the global greenhouse gas emissions (Adriane et.al, 2017). To solve this problem an alternative low carbon construction material should be used. Bamboo plastic composites is the suitable alternative. This material is renewable and its production can be easily sustained for longer period with the necessary management. Bamboo is able to capture carbon(iv)oxide during its growth phase and store it into its tissues, this significantly minimize the atmospheric carbon dioxide. The figure below shows the preferred species of bamboo in the development of BPC.

Source:(google,2019)

Fig1.1 figure of bamboo species used in analysis

Engineered bamboo products should be used in the construction of building structural elements. With this system a glue is used to laminate bamboo elements, with this the system is standardized hence making its adoption to be simpler in terms of construction and design. From various research conducted it is estimated that engineered bamboo products are able to sequester 15.65kg of carbon dioxide per kg of the product this means that the material is sustainable and significantly reduces the available carbon dioxide footprint (Ahmad & Kauke, 2015).

Life cycle assessment(LCA) has been and efficient and effective method of assessing the environmental performance of construction material. The main feature of this method is that it is able to be used in identification of the promising strategies of improving sustainability performance of a material throughout its supply chain and service life.

Another product that can be used in construction industry is the wood plastic composite(WPC). This are bio-composites which are manufactured by accurately mixing lignocellulos fibers, wood and wood flour. The material is eco-friendly and has low maintenance cost, the suburb mechanical properties has made it to be used in various friendly such as construction, automotive, residential market and outdoor structures. Although the material has been suitable to be used in construction it has one main drawback, the material has low monolithic properties this can be attributed to the poor compatibility between the polymer matrix of the material and the wood flour. But with the use of maleic anhydride grafted polyethylene the interfacial interaction of WPC can be improved hence increased compatibility. To further increase the strength of WPC much emphasis should be placed in the construction and the morphology of natural fibers. Accurate proportions of fiber content and mixture ration of glass fiber and polypropylene will have a drastic impact of the flexural and tensile properties of the composite. From various material science research, it has been shown that the use of white mud and bamboo pulp fibers increases the overall mechanical properties of WPC. Since cost is an important criterion in selection of material the white mud and bamboo pulp fibers used in reinforcing the bamboo plastic (BPC) should be manufactured using extrusion technology since it is economically feasible. BCP composites can also be supplemented by other natural materials such as sisal, kenaf, cellulose fibers and jute to increase their mechanical performance. Furthermore, blending tea residue can also be blended with high density polyethylene to manufacture supporting beams which can be used in construction. With these material overall environmental pollution can be minimized since industrial waste are recycled and are used in construction of building support structures (Ammunidin & Ablatiff,2011).

Benefits of Bamboo Plastic Composites in Construction

To outline the role of engineering and material science in the development of eco-friendly and sustainable materials.

To show the effects of greenhouse gases to the environment, economy and the livelihood

To ascertain the use of bamboo composite material as a suitable alternative material to be used in construction since it has a lower carbon footprint.

Evaluate suitable future material science developments that can be implemented to minimize the global carbon footprint.

(i)Material methods

The bamboo plastic composite(BPC) is manufactured by mixing bamboo reinforcing fibers(BRF), high density polyethylene(HDPE), white mud(WM)and bamboo pulp fibers. For the HDPE suitable for use must have a density of around 0.945g/cm3 and have an appropriate melting mass flow rate for easy mixing. Since all the material used are incompatible the maleic anhydride grafted polyethylene is used as the interfacial compactibilizer. With this chemical the final product is usually stable an evenly mixed and irregularity cases are further minimized. To improve the lubricity of BPC, PE-wax is used this wax is used during the early stages of the development of BPC(Andam,2015).

The manufacturing process of BPC is usually simple and the carbon footprint extremely low. The first step of manufacturing is done by preparing the composites by using a 4.5cm conical extruder. After this has been done the acceptable volume fractions of White mud(WM) and bamboo pulp fiber(BPF) are calculated according to the loading requirement of the building structure under construction. After analysis of the respective volume fraction of the material the raw material is mixed while considering the loading requirements. With the use of double-screw extruder the mixture is the subjected to melt-bending this is done at optimum temperature of around 170C, the composite is then extruded and passed through a die then cooled at room temperature and later granulated with the use of a grinder. The material obtained can then be shaped into the appropriated shaped to be used in the construction of any building structure (Benoit & Mazijin,2018).

To further assess the suitability of the material the dimensions should be checked with an optical microscope and the BPC tensile strength should be measured with the use of a micro-tester

(ii)Life cycle assessment (LCA)

With the use of CES-Edupack the environmental impact of various building material is assessed. The LCA assessment is considered to be having two stages, construction process and product. Five phases are used to simplify the analysis this includes construction scenario, manufacturing, extraction process of raw materials used, transport scenario and transportation means (Khandal et.al,2011). The figure below shows the building assessment information which was used in the analysis of carbon footprint production. 

Manufacturing Process of Bamboo Plastic Composites

Source:(Soila,2015)

Fig1.2 representation of building assessment information

In this project much emphasis is not placed on the end-of-life phase since it has a lot of inherent uncertainty. With the information generated from the CES-Edupack results it was noted that the LCA accounted for the significant amount of composites which were required for construction of supporting beams and trusses which were used in the construction. The geographical position of the building under construction will greatly affect the carbon footprint analysis of the construction material. Assuming that the building is located in a developing nation located in Africa, this means that the technical conditions and the specific climate will have an impact on the heating and cooling methods used in the manufacturing of BPC, since artificial heating and cooling is not common in the area, this will imply that main demand of energy will be from the appliances used in manufacturing and the lighting which both are not material-dependent.

For the project the functional unit used in the analysis was defined by the amount carbon dioxide gas produced by the square meter of building under construction.in this case the carbon footprint was to be related to the transportation and the manufacturing process of the building materials.

For better comparison between bamboo plastic composite(BPC) and other traditional materials the life cycle inventory is created for all of the materials under comparison. This is done by collecting LCI and geographic information system data with this the carbon footprint produced during transportation can be easily assessed. In order to calculate the LCI various criteria are considered they include; low performance, the mean performance and high performance. With this method the visualization of environmental impacts can be easily done while allowing subsequent checking of uncertainty(Cleaver,2013).

The second step involves checking of the respective transport distance of the materials from their manufacturing centers. With this the production centers of cement, bamboo and glue-laminated bamboo are analyzed, the obtained centers are marked and georeferenced with the use of a GIS software. The figure below shows an overview of the transportation distances which were used in the calculation of the carbon foot print produced by each material. fig1.2 

Source:(Maina,2020)

Fig 1.3 transport distances used in the life cycle assessment analyisis

To property do impact assessment of each material SIMApro v8 software can be used, this tool is able to do analysis of emissions produced due to human activities.as for this case the will include the transportation, production and extraction of the building material, thus the subsequent equivalent mass of carbon dioxide produced is calculated. The main drawback of using this method for analysis is that it fails to account for the carbon dioxide stored by the bio-composites, for now there is no consensus on the appropriate method to be used in the carbon footprint accounting(Gratani,2016).

Life Cycle Assessment

In order to overcome this methodological challenge (Zeal et.al 2016) proposed a method of carbon dioxide balance. With this method the amount of carbon dioxide which was used by the bio-composites is calculated then the value is subtracted from the carbon dioxide emission produced in the extraction, manufacturing and the transportation process. As for the buildings a similar balance is also done, the overall carbon foot print from the manufacturing process is calculated and then the amount of carbon dioxide stored in the bio-composite is subtracted from the value. This means that if the overall value obtained is negative, this means that the material is sustainable and therefore a reduction of atmospheric carbon dioxide is experience. A negative value is obtained for BCP and bamboo, hence implying that the materials are eco-friendly. As for the traditional material such as concrete and steel a positive value is obtained hence the material increases the amount of greenhouse gases into the atmosphere.

It is also very vital to note that highest variation is seen in unsustainable materials such as brick and concrete while vice versa is true for sustainable materials such as bamboo and its composites (Klaus,2011). This means that concrete buildings are extremely sensitive to any kind of variation in transportation and production efficiency compared to bio-based material buildings. The table below shows the CES-Edupack results for the carbon footprint production.

Phase	The total Energy used (MJ)	Percent of Energy used (%)	Mass of Carbon dioxide  (kg)	Percent of carbon dioxide (%)
Material(Bamboo plastic composite)	344	85.7	9.6	47.1
Manufacturing process	86.8	21.6	6.94	34.1
Transportation	48.7	12.1	3.46	17.0
The usage	50.8	12.7	3.05	15.0
The approximate End of life	-240	-32.1	-2.68	-13.2
Total	401	100	20.4	100

 

Source:(Design,2020)

Fig 1.0 graph of carbon footprint

The figure below shows the model used in the life cycle assessment(LCA)

Source:(Ngatia,2011)

Fig 1.5 life cycle assessment model

Material solution mechanical properties

The table below shows a comparison of mechanical properties of bio-based material and other traditional construction materials.

Building material	Compressive strength()	Tensile strength()	The specific modulus()
Unidirectional GRP	170.4	245.0	23,456
bamboo	79.5	215.6	22,900
Polymer resin	99.6	41.2	4,245
GRP	88.8	120.5	5,123
BPC	209.4	309.4	21,890

Mechanical properties	Bamboo plastic composite(BPC)	Natural bamboo
Tensile strength	285.75Mpa	202.45Mpa
Flexural modulus	21.62Gpa	12.97Gpa
Fiber volume fraction	41.9%	30.2%
Specific density	0.95g/cm2	0.62g/cm2
Flexural strength	298.74Mpa	208.76Mpa
Compressive strength	119.30Mpa	77.92Mpa
The coefficient of shrinkage	0.398	0.752

 

Source:(Design,2020)

Fig 1.6 CES-Edupack bubble chart analysis of various construction materials

For the material selection Ashby methodology is used, with this method four basic steps are followed;

The design requirement is expressed as constrain and objectives as for our case the material should have appropriate mechanical properties and a lower carbon footprint.

The next step is screen various materials which are not able to do the job are eliminated, traditional building materials have a good mechanical strength and a high carbon footprint hence eliminated.

After screening the material remaining are ranked according to their efficiency in doing the task, in this stage supporting information is necessary since it allows the designer to explore the pedigrees of the suitable composites for the task.

Impact Assessment of Materials

Conclusion

To conclude from the results obtained in the project it was shown that the main contributors to increased carbon footprint was traditional material (concrete and steel), transportation and reinforcing steel. With this notion design stages should not only consider the structural loading but should also factor in the environmental impact of using the material. It can also be noted that locally available materials should always be preferred, this minimizes the transportation distance which significantly decrease the carbon footprint of the material. To further increase the efficiency of bamboo based construction system, a decentralized production process is suggested, with this method the energy demand is greatly reduced. As for the life cycle assessment done, there was scarcity of data and therefore the representation done was just an overview of the product, there is need for development of new models which should be as the basis for enhancing sustainable manufacturing of bamboo composites. It is very important to note that the values obtained from the analysis may significantly vary according to the geographical position of the construction site(Liese,2014). This can be attributed to difference in regulatory measures at different production facilities and the change in the transportation distances. Moreover, for sustainable building to be a future reality strict policies should be put in place, this policy will control the harvesting of bamboo and ensure only mature plants are harvested. Since the natural energy sources are being depleted rapidly, great yielding bamboo species should be developed, this species should be introduced into the tropical and subtropical countries were sustainable growth of bamboo can be achieved.

In order to make the manufacturing process of bamboo plastic composites(BCP) easier the following measure are supposed to be taken to improve the bamboo cultivation since it is the main material used to manufacture the composite(Naxim,2016). This measure includes;

A lot of priorities should be placed in the cultivation of high yielding bamboo species. This species should have a higher fiber content and should be able to survive in adverse weather conditions.

The manufacturing centers for bamboo products should be advised to use eco-friendly additives, the suggested additives include raisins and natural preservatives.

Recycling and Take-back techniques should be used to minimize the pollution, since most of the bamboo products are 100% reusable this will be easier to achieve.

Much research should be conducted on the field, this will enable material scientist to come up with new industrial products which may supplement bamboo based construction system, this product may include corrugated bamboo which has suburb mechanical properties.

More efficient manufacturing methods should be used, this will greatly minimize the energy use in the transformation of bamboo to finished products hence decreasing the carbon footprint produced during manufacturing and extraction process.

References

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