1 Introduction
2 Materials and methods
2.1 Description of assessed floor slabs
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Model A: Prefab piece made of cement mortar including recycled mixed PP. This model includes the recently patented prefab cement mortar with recycled mixed polypropylene interjoist filling piece (recycled mixed PP vault).
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Model B: Ceramic piece with horizontal upper surface. This model includes a prefab ceramic interjoist filling piece. The upper side of this piece is horizontal.
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Model C: Ceramic piece with arched upper surface. This model includes a ceramic prefab interjoist filling piece. Both the upper side and the inferior side of this piece are arch shaped; this commercial model is considered a traditional piece.
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Model D: Concrete piece with horizontal upper surface. This model includes a prefab concrete mortar interjoist filling piece. The upper side of this piece is horizontal.
Length (cm) | Height (cm) | Width (cm) | Weight per unit (kg) | |
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Model A: slab with recycled mixed PP vault | 36.00 | 12.00 | 25.00 | 8.32 |
Model B: ceramic piece with horizontal upper surface | 50.00 | 14.00 | 25.00 | 8.50 |
Model C: ceramic piece with arched upper surface | 50.00 | 14.5 | 22.00 | 3.00 |
Model D: cement mortar vault | 60.00 | 20.00 | 18.00 | 14.50 |
Interjoist filler (kg/m2) | Concrete (kg/m2) | Timber beam (kg/m2) | Stainless steel beam connectors (kg/m2) | Reinforcement steel mesh (kg/m2) | |
---|---|---|---|---|---|
Model A: slab with recycled mixed PP vault | 69.33 | 239.58 | 16.00 | 0.42 | 2.20 |
Model B: ceramic piece with horizontal upper surface | 54.84 | 319.6 | 15.48 | 0.32 | 2.20 |
Model C: ceramic piece with arched upper surface | 21.99 | 373.9 | 15.48 | 0.32 | 2.20 |
Model D: cement mortar vault | 105.99 | 252.63 | 16.84 | 0.35 | 2.20 |
2.2 Methodology
2.2.1 Goal definition
2.2.2 Functional unit
2.2.3 System boundary
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A1: Extraction and processing of raw materials, secondary materials input processing.
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A2: Transport to the manufacturer.
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A3: Production at factory, to the final product at the gate of the factory. Including energy consumption and processing of wastes.
2.2.4 Allocation criteria
Impact category | 1 ton recycled mixed PP production |
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Abiotic depletion (ADPE) | 2.91E−04 |
Abiotic depletion (fossil fuels) (ADPF) | 1.59E+03 |
Global warming (GWP100a) | 1.63E+02 |
Ozone layer depletion (ODP) | 1.90E−05 |
Photochemical oxidation | 4.29E−02 |
Acidification | 9.74E−01 |
Eutrophication | 2.85E−01 |
2.2.5 Life cycle inventory
Elementary component | Data | Process | Source |
---|---|---|---|
Materials common to all models | |||
Concrete | Generic database | Market for concrete, normal, GLO. | Ecoinvent database |
Timber beam | Generic database | Market for sawnwood, hardwood, raw, GLO. | Ecoinvent database |
Stainless steel beam connectors | Generic database | Market for steel, chromium steel 18/8, GLO. | Ecoinvent database |
Reinforcement steel mesh | Generic database | Market for reinforcing steel, GLO. | Ecoinvent database |
Specific materials for each model | |||
Model A | Specific | Prefab piece made of cement mortar including recycled mixed PP Cradle to gate LCA. | Patent process (Rubio-de Hita et al. 2018) |
Model B | Specific | Ceramic vaults and hollow blocks. Environmental Product Declaration EN 15804 (2012) 2012+A1:2014 | EPD Hyspalit (AENOR 2017) |
Model C | Specific | Ceramic vaults and hollow blocks. Environmental Product Declaration EN 15804 (2012) 2012+A1:2014 | EPD Hyspalit (AENOR 2017) |
Model D | Specific | Concrete vaults and hollow blocks. Environmental Product Declaration EN 15804 (2012) 2012+A1:2014 | EPD Andece (ANDECE 2020) |
Unit | Elementary flow | Source | |
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Material consumption (kg) | |||
Cement | 1.55E-01 | Cement production, Portland, Europe without Switzerland. | Ecoinvent database |
Water | 1.20E-01 | Tap water production, conventional treatment, Europe without Switzerland | Ecoinvent database |
Sand | 6.24E-01 | Sand 0/2, wet and dry quarry, production mix, at plant, undried, EU-27 S System. | ELCD database |
Recycled mixed PP | 1.02E-01 | Obtained according production process information. | Patented product |
Transport (ton km) | |||
Lorry | 4.37E-02 | market for transport, freight, lorry 16–32 metric ton, EURO5, RER. | Ecoinvent database |
Energy consumption (W) | |||
Electricity | 2.03E+00 | market for electricity, low voltage, ES. | Ecoinvent database |
Impact category | Units | 1 ton recycled mixed PP vault production |
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Abiotic depletion (ADPE) | kg Sb eq | 9.72E−05 |
Abiotic depletion (fossil fuels) (ADPF) | MJ | 5.97E+02 |
Global warming (GWP100a) | kg CO2 eq | 9.59E+01 |
Ozone layer depletion (ODP) | kg CFC-11 eq | 5.98E−06 |
Photochemical oxidation | kg C2H4 eq | 1.21E−02 |
Acidification | kg SO2 eq | 2.81E−01 |
Eutrophication | kg PO4 eq | 7.79E−02 |
Human toxicity | kg 1,4-DB eq | 1.67E−02 |
Impact category | Units | 1 ton precast cement mortar vault production |
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Abiotic depletion (ADPE) | kg Sb eq | 1.02E−05 |
Abiotic depletion (fossil fuels) (ADPF) | MJ | 2.41E+03 |
Global warming (GWP100a) | kg CO2 eq | 2.40+02 |
Ozone layer depletion (ODP) | kg CFC-11 eq | 6.29−08 |
Photochemical oxidation | kg C2H4 eq | 9.07E−02 |
Acidification | kg SO2 eq | 1.00E−00 |
Eutrophication | kg PO4 eq | 6.51E−02 |
Impact category | Units | 1 ton precast cement mortar vault production |
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Abiotic depletion (ADPE) | kg Sb eq | 9.05E−06 |
Abiotic depletion (fossil fuels) (ADPF) | MJ | 6.20E+02 |
Global warming (GWP100a) | kg CO2 eq | 7.68E+01 |
Ozone layer depletion (ODP) | kg CFC-11 eq | 8.46E−06 |
Photochemical oxidation | kg C2H4 eq | 1.92E−02 |
Acidification | kg SO2 eq | 2.01E−01 |
Eutrophication | kg PO4 eq | 4.50E−02 |
2.2.6 Impact assessment
3 Results and discussion
Impact category | Units | Model A | Model B | Model C | Model D |
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Abiotic depletion | kg Sb eq | 1.31E−04 | 1.25E−04 | 1.34E−04 | 1.20E−04 |
Abiotic depletion (fossil fuels) | MJ | 3.67E+02 | 5.13E+02 | 4.76E+02 | 4.01E+02 |
Global warming (GWP100a) | kg CO2 eq | 4.81E+01 | 6.39E+01 | 6.27E+01 | 5.12E+01 |
Ozone layer depletion (ODP) | kg CFC-11 eq | 3.25E−06 | 3.37E−06 | 3.76E−06 | 3.85E−06 |
Photochemical oxidation | kg C2H4 eq | 1.16E−02 | 1.67E−02 | 1.45E−02 | 1.31E−02 |
Acidification | kg SO2 eq | 1.52E−01 | 2.10E−01 | 1.94E−01 | 1.57E−01 |
Eutrophication | kg PO4 eq | 4.97E−02 | 5.48E−02 | 5.80E−02 | 5.01E−02 |
3.1 Normalisation
3.2 Contribution analysis
3.2.1 Contribution analysis for model A slab
3.2.2 Contribution analysis for model A vault
3.2.3 Contribution analysis for recycled mixed PP
3.3 Sensitivity analysis
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Model A slab production step: concrete use. Mixed PP vault is the second contributor in GWP impact score
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Model A mixed PP vault production step: use of cement. Use of recycled mixed PP is the second contributor.
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Recycled mixed PP production step: electricity consumption is the largest contributor. Transport process is the second contributor.
3.3.1 Transport distance sensitivity analysis. Recycled mixed pp production step
Transport sensitivity analysis Model A Recycled mixed PP production | Reference scenario transport 74.25 Tkm | Sensitivity (+50%) Transport 37.12 Tkm | Sensitivity (−50%) Transport 111.37 Tkm | Sensitivity (+50%) Transport 111.37 Tkm (%) variation | Sensitivity (−50%) Transport 37.12 Tkm (%) variation |
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Abiotic depletion | 1.29E−04 | 1.29E−04 | 1.29E−04 | 0.21 | −0.23 |
Abiotic depletion (fossil fuels) | 3.66E+02 | 3.67E+02 | 3.64E+02 | 0.37 | −0.40 |
Global warming (GWP100a) | 4.81E+01 | 4.82E+01 | 4.80E+01 | 0.18 | −0.21 |
Ozone layer depletion (ODP) | 3.25E−06 | 3.26E−06 | 3.23E−06 | 0.51 | −0.55 |
Photochemical oxidation | 1.16E−02 | 1.16E−02 | 1.16E−02 | 0.12 | −0.14 |
Acidification | 1.52E−01 | 1.52E−01 | 1.51E−01 | 0.17 | −0.22 |
Eutrophication | 4.96E−02 | 4.96E−02 | 4.95E−02 | 0.12 | −0.16 |
3.3.2 Electricity consumption sensitivity analysis. Recycled mixed pp production step
Electricity sensitivity analysis Model A Recycled mixed PP production | Reference scenario | Sensitivity electricity (+50%) Increase | Sensitivity electricity (−50%) Reduction | Sensitivity (+50%) Electricity % variation | Sensitivity (−50%) Electricity % variation |
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Abiotic depletion | 1.29E−04 | 1.30E−04 | 1.28E−04 | 0.43 | −0.89 |
Abiotic depletion (fossil fuels) | 3.66E+02 | 3.69E+02 | 3.60E+02 | 0.84 | −1.64 |
Global warming (GWP100a) | 4.81E+01 | 4.84E+01 | 4.75E+01 | 0.7 | −1.12 |
Ozone layer depletion (ODP) | 3.25E−06 | 3.28E−06 | 3.17E−06 | 1.12 | −2.24 |
Photochemical oxidation | 1.16E−02 | 1.17E−02 | 1.15E−02 | 0.97 | −1.27 |
Acidification | 1.52E−01 | 1.55E−01 | 1.48E−01 | 2.02 | −2.5 |
Eutrophication | 4.96E−02 | 5.02E−02 | 4.88E−02 | 1.3 | −1.62 |
3.4 Discussion of results
4 Conclusions
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The flooring assessed systems incorporating ceramic vaults bear far worse scores in GWP100a and AD fossil fuel categories.
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The conducted contribution and sensitivity analysis conclusion is that the assessed recycled mixed PP vault has a reduced density, and fills the slab interjoist space with less mass consumption per square metre of slab; therefore, the impact score for model A slab is lower than assessed commercial slabs.
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Specific data used, corresponding to ceramic and cement mortar vaults, has been obtained from commercial models representing the current state of the art for Spanish construction market. Specific data for recycled mixed PP vault (model A) has been obtained from prototype production process. Therefore, the results obtained are considered to be representative of Spain current construction market.
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The research has been conducted following EN 15804 (2012) rules; consequently, obtained results can be compared with any other research applying the same standard and dealing with the same functional unit.
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This example shows the benefits of the construction sector to incorporate recycled plastics. This leads to an enhanced environmental performance and to a reduction of plastics waste (da Silva et al. 2021).
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Obtained results can encourage the research in the incorporation of recycled plastics in construction products.
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Bearing in mind that this study assesses the impacts corresponding to a recycled mixed PP vault prototype (model A), it is considered that there is room for further investigation on this new piece production process optimisation and consequently for further environmental impact score reduction.