Life-Cycle Analysis and Multi-Criteria Decision Analysis for a Reinforced Concrete Villa

 Goal and scope of the assessment:

The main goal of this assessment is to do a carbon footprint analysis. An analysis of one’s carbon footprint sheds light on how much carbon dioxide and other greenhouse gases are released as a result of different actions. Individuals and businesses can contribute to international efforts to prevent climate change by reducing their carbon footprint by being aware of these emissions. Finding areas for resource optimization is made easier by analyzing carbon footprints

Below is the goal and boundary of the system.

Parameters and Design Options:

Design Option	Beams Material	Slab Material
Option 1	Reinforced Concrete	Reinforced Concrete
Option 2	Fly Ash reinforced Concrete	Fly Ash reinforced Concrete
Option 3	Ground granulated blast-furnace slag Reinforced Concrete	Ground granulated blast-furnace slag Reinforced Concrete

 

Element	Dimensions (width * height )	Material
RC Beams	(0.3 * 0.5 )	42.5 MPA, Mix 1 [1]
RC Slab	(15 * 0.2 )	42.5 MPA, Mix 1 [1]
FA RC Beams	0.8 * RC Beams	42.5 MPA, Mix 2 [1]
FA RC Slab	0.8 * RC Slab	42.5 MPA, Mix 2 [1]
GGBS RC Beams	0.7 * RC Beams	42.5 MPA, Mix 3 [1]
GGBS RC Slab	0.7 * RC Slab	42.5 MPA, Mix 3 [1]

First option: In order to ensure a structure’s structural integrity and support different loads, reinforced concrete beams and slabs are essential components. Ensuring the overall safety and function of the structure depends on the proper design and detailing of these components. This option includes the usual concrete components, cement, big and small aggregates, and water.

Second Option: Fly Ash Concrete. Producing cement is energy-intensive and emits a large amount of CO2. Waste products like fly ash can be used as an alternative to cement, thereby minimizing cement consumption, and thus, FA can be beneficial both environmentally and economically [2]. Furthermore, such a high utilization of FA is vital for sustainable development because waste resources may be utilized as efficiently as feasible.

Third Option: Ground Granulated Blast Furnace Slag (GGBS) reinforced concrete, also known as slag cement concrete, is a type of concrete that incorporates GGBS as a partial replacement for Portland cement. Adding the GGBS to the concrete mix design can increase the compressive strength [3]. The total carbon footprint of producing concrete can be decreased by using GGBS in place of cement [1]. GGBS is an industrial by-product, therefore using it in concrete is a way to make use of something that may otherwise be thrown away.

System lifespan with interventions:

S = Stitching          G= Grouting        RS= Routing and Sealing          FR= Full Replacement

The events are based on [4].The lifespan is 108 years, similar to what have been studied at the 1^st assignment. In concrete repair, grouting is used to seal gaps, cavities, and cracks in buildings. In RC, the Grout frequency is 9 years, unlike in FA RC and GGBS RC, because the fly ash and ground granulated blast furnace slag can increase the compressive strength. Installing extra materials, like steel rods or plates, to stabilize and bridge structural discontinuities is known as stitching. It keeps forces from building up in weak spots in the structure by redistributing loads and stress throughout the stitched area.  Routing is the technique of making a rectangular shape more consistent and widening a crack in order to prepare it for sealing. It is applied after 27 years in most design options because large cracks can appear within this time. Full replacement is required only in RC design option after 54 years when the deterioration level becomes significantly high.

Life Cycle Inventory and Analysis:

The Amount of quantities of materials and emissions are based on [1]. Some missing values for reinforcement and other indicators were assumed Based on [5].

The results favor the third option over the second and first. This confirms that the use of GGBS reinforced concrete saves energy and reduces the amount of gases emitted. It is considered environmentally friendly, and the results are logical when comparing them with the study case that has been done by [1].

Cost Analysis:

Materials	Energy	Co2	NOX	SOX
Quantities Option1	621,353	57,675,941	674,985.2	630,472.8
Maintenance and production cost Option1	248541.2	720949.263	11249.75	9006.7429
Overall cost 1051882

 

Materials	Energy	Co2	NOX	SOX
Quantities Option2	307,432	28,577,238	233,419.3	278,972
Maintenance and production cost Option2	122972.8	357215.475	38856.98333	3985.3143
Overall cost 553773

 

Materials	Energy	Co2	NOX	SOX
Quantities Option3	268,800.6	24,966,081	129,373.8	220,353.6
Maintenance and production cost Option3	134400	312076.01	2156.21	3147.9
Overall cost 451780

Looking at the results obtained from Life Cycle Inventory and Analysis, The matrices of Energy, Co2, NOX, and SOX are defined based on the comparison of the results and using Saaty scale.

To conclude, CO2 is the most important factor because its quantity and price are the highest with a very clear difference among the others. After that, The energy has less importance than CO2 but more than SOX AND NOX. The main goal of this study was to evaluate the energy and emission, thus we are trying to decrease them. In order to achieve that, the numbers in the CWPC Matrix were formed to take into consideration the most important results.

The results are similar to the results of the study that was taken as a reference in this study and to the results of life cycle inventory and analysis. The third Design option is the optimum one. It can be considered as the most friendly environment option. As the goal of this study is to study the emission and energy, the 3^rd option emits the lowest amount of gases, and consumes the least energy. Thus, GGBS design option must be used For concrete to be more long-lasting, stronger over time, and to support ecologically friendly and sustainable building methods.

The trade-offs can be

• (cost vs. performance): Higher-performing components or materials could cost more. Materials like Ground Granulated Blast-furnace Slag and fly ash are environmentally friendly and are being used as a replacement for the Portland cement, and their cost is not high. Thus we can pay reasonable number for adding higher amounts of GGBS.
• (Cost vs. durability): Using expensive materials may result in a material with higher durability. Ground Granulated Blast-furnace Slag reduces the permeability, resists chemicals and freezing, reduces cracks, and provides long-term performance due to the hydration products in it.
• (Performance vs. environmental impact): Choosing eco-friendly materials may also have improve the performance needed to achieve the LCA goal.

 

 

References used:

[1].Tait, M. and Cheung, W. (2016). A comparative cradle-to-gate life cycle assessment of three. International journal of life cycle assessment, 21:848-858.

 

[2].Nayak, D. and Singh, R. and Kumar, R. (2022). Fly ash for sustainable construction: A review of fly ash concrete and its beneficial use case studies. Indian Institute of Technology (BHU), pp.1-3.

[3].Kumar, V. and Garikipati, V. and Raju, P. (2015). Strength and Durability Studies on GGBS Concrete. International Journal of Civil Engineering, 10(2), pp.34-38.

[4].Bahadur, S. (2018). A minor project report on protection, repair, and maintenance of RCC structures. Geeta engineering college, pp.33-37.

[5].Marceau, M., Nisbet, M.A. and Van Geem, M.G. (2007). Life cycle inventory of portland cement concrete. Portland Cement Association, pp.80-100