Thermal Performance of Concrete with Recycled Concrete Powder as Partial Cement Replacement and Recycled CDW Aggregate
Abstract
:1. Introduction
2. Materials and Methods
2.1. Materials
2.1.1. Binders
2.1.2. Aggregates
2.2. Testing and methodology
2.3. Concrete Design
3. Results
3.1. Fresh Properties
3.2. Mechanical Properties
3.3. Physical Properties
3.3.1. Dry Density
3.3.2. Open Porosity
3.3.3. Electrical Conductivity
3.4. Thermal Properties
3.4.1. Thermal Conductivity
3.4.2. Specific Heat Capacity
3.5. Cross-Property Relationships
3.5.1. Thermal Properties and Air Content
3.5.2. Thermal Properties and Compressive Strength
3.5.3. Thermal Properties and Open Porosity
3.5.4. Thermal Properties and Electrical Conductivity
4. Conclusions
- The use of GRC to replace 25% of OPC and MRA to replace 50% of NA lowered concrete fresh-state density by 6.2% and raised its air content by 30%. All the recycled material concrete mixes studied had an air content under 4.5%, the upper limit recommended by the ACI committee for structural concrete;
- Porosity rose by 39.7% in the mixes with 25% GRC and 50% MRA and by 13.2% in the mixes with 25% GRC and 100% NA relative to the reference mix made with 100% OPC and 100% NA;
- The decline in dry density and the rise in electrical conductivity were associated with the incorporation of GRC in mixes with 100% NA as well as those with 50% MRA due to the higher porosity in the recycled materials;
- The use of 25% GRC in conjunction with 50% MRA reduced thermal conductivity by 11.8% and raised specific heat capacity by 9.1%, whilst the values for 25% GRC with 100% NA were a 6.9% reduction in thermal conductivity and a 4.1% rise in specific heat capacity, both relative to concrete with 100% natural aggregate (NA);
- Due to their greater porosity, the new recycled materials concrete may provide better thermal insulation and greater thermal inertia than conventional concrete;
- Cross-referencing concrete properties showed that, whereas using GRC and MRA as replacement materials had an adverse effect on concrete’s compressive strength, it improved its thermal properties;
- Mixes with 25% GRC and 100% NA and those with 10% GRC and 50% MRA, with compressive strength values of >25 MPa, are not only apt for use in building construction, but afford greater energy efficiency than conventional concrete.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Property | OPC | RB10 | RB25 | EN 197-1 1 | |
---|---|---|---|---|---|
Setting time (min) | Initial | 84 | 90 | 91 | ≥60 |
Final | 136 | 138 | 141 | - | |
Water content (g) | 143 | 144 | 147 | - | |
Normal consistency (mm) | 36 | 35 | 35 | 34 ± 2 | |
28 d compressive strength (MPa) | 67.5 ± 1.0 | 62.6 ± 1.0 | 51.39 ± 2.2 | ≥42.5 |
Parameter | Value | Property | Value |
---|---|---|---|
Cement type | CEM II/A-L 42.5 R | Slump class 2 | S3 |
Cement content | 300 kg/m3 | Compressive strength 3 | 39.8 MPa |
w/ceff 1 | 0.55 | Splitting tensile strength 3 | 2.75 MPa |
Coarse aggregate | 1020 kg/m3 (crushed limestone) | Modulus of elasticity 3 | 38.9 GPa |
Fine aggregate | 910 kg/m3 (natural river sand) |
Constituent | Label | Content (wt%) |
---|---|---|
Concrete and mortar | Rc | 47.1 |
Natural stone | Ru | 25.2 |
Clay materials | Rb | 22.6 |
Bituminous materials | Ra | 0.2 |
Glass | Rg | 1.7 |
Floating particles | FL | 1 |
Gypsum | X1 | 1.8 |
Metals | X2 | 0.4 |
Property | NS-F | NS-C | NC-M | NC-G | MRA | EHE 08 |
---|---|---|---|---|---|---|
Dry density (kg/m3) [30] | 2581 | 2583 | 2600 | 2620 | 2069 | - |
SSD 1 density (kg/m3) [30] | 2601 | 2609 | 2630 | 2670 | 2256 | - |
24 h water absorption (wt%) [30] | 0.4 | 0.5 | 1.3 | 1.3 | 9.1 | ≤5 |
10 min water absorption (wt%) [31] | 0.2 | 0.3 | 0.5 | 0.6 | 8.1 | - |
Los Angeles coefficient (wt%) [32] | - | - | 28 | 26 | 46 | ≤40 |
Flakiness index (wt%) [33]. | - | - | 13 | 16 | 20 | <35 |
Parameter Tested | Standard | Specimen Dimensions |
---|---|---|
Fresh properties | ||
Slump | EN 12350:2 [35] | - |
Fresh density | EN 12350-6 [36] | |
Air content | EN 12350-7 [37] | |
Mechanical properties | ||
Compressive strength | EN 12390-3 [38] | 150 mm Ø × 300 mm |
Tensile strength | ||
Physical properties | ||
Open porosity Dry density | UNE 83,980 [39] | 100 × 100 × 100 mm |
Electrical resistivity | UNE 83988-2 [40] | 100 mm Ø × 200 mm |
Thermal properties | ||
Thermal conductivity | ISOMET 2114 [41] | 100 × 100 × 500 mm |
Volume heat capacity |
Component | Amount (kg/m3) | |||||
---|---|---|---|---|---|---|
NAC | N10/0 | N25/0 | R0/50 | R10/50 | R25/50 | |
Cement | 300.0 | 270.0 | 225.0 | 300.0 | 270.0 | 225.0 |
GRC | - | 30.0 | 75.0 | - | 30.0 | 75.0 |
Total water | 171.3 | 177.1 | 183.3 | 205.2 | 211.2 | 217.2 |
NS-F | 154.0 | 150.0 | 154.0 | 154.0 | 154.0 | 154.0 |
NS-C | 754.5 | 754.5 | 754.5 | 754.5 | 754.5 | 754.5 |
NG-M | 367.0 | 367.0 | 367.0 | 183.6 | 183.6 | 183.6 |
NG-G | 653.0 | 653.0 | 653.0 | 326.5 | 326.5 | 326.5 |
MRA | - | - | - | 449.0 | 449.0 | 449.0 |
Agg. Group | Mix | w/beff | Slump (mm) | Density (kg/m3) | Air Content (vol%) |
---|---|---|---|---|---|
NA | NAC | 0.56 | 65 ± 2.8 | 2367 ± 8 | 2.6 ± 0.2 |
N10/0 | 0.58 | 74 ± 2.5 | 2340 ± 9 | 2.7 ± 0.2 | |
N25/0 | 0.60 | 65 ± 3.7 | 2309 ± 10 | 2.9 ± 0.1 | |
MRA | R0/50 | 0.59 | 75 ± 3.1 | 2251 ± 11 | 3.2 ± 0.1 |
R10/50 | 0.61 | 61 ± 3.7 | 2244 ± 12 | 3.4 ± 0.2 | |
R25/50 | 0.63 | 63 ± 4.2 | 2219 ± 10 | 3.8 ± 0.2 |
NA mix | MRA mix | |||||
---|---|---|---|---|---|---|
Parameter/Differential | NAC | N10/0 | N25/0 | R0/50 | R10/50 | R25/50 |
ρdry (kg/m3) | 2290 ± 35 | 2227 ± 20 | 2158 ± 25 | 2101 ± 40 | 2052 ± 38 | 1990 ± 42 |
Δ with GRC (%) | - | −2.8 | −5.8 | - | −2.3 | −5.3 |
Δ with MRA (%) | -8.3 | −7.9 | −7.8 | |||
Δ with GRC (%) × MRA (%) | −10.4 | −13.1 | ||||
Po (vol%) | 12.1 ± 0.2 | 12.7 ± 0.3 | 13.7 ± 0.3 | 15.2 ± 0.4 | 15.9 ± 0.5 | 16.9 ± 0.3 |
Δ with GRC (%) | - | 5.0 | 13.2 | - | 4.6 | 11.2 |
Δ with MRA (%) | 26.5 | 25.2 | 23.4 | |||
Δ with GRC (%) × MRA (%) | 31.4 | 39.7 | ||||
EC (10−3 Ω·m−1) | 8.8 ± 0.5 | 9.5 ± 0.3 | 10.6 ± 0.3 | 9.9 ± 0.3 | 10.2 ± 0.2 | 11.1 ± 0.4 |
Δ with GRC (%) | - | −7.1 | −16.8 | − | −3.0 | −10.9 |
Δ with MRA (%) | −10.6 | −6.7 | −4.3 | |||
Δ with GRC (%) × MRA (%) | −13.3 | −20.4 |
NA mix | MRA mix | |||||
---|---|---|---|---|---|---|
Parameter/Differential | NAC | N10/0 | N25/0 | R0/50 | R10/50 | R25/50 |
λ (W/m·K) 1 | 2.064 | 2.013 | 1.922 | 1.963 | 1.901 | 1.821 |
Δ with GRC (%) | - | −2.5 | −6.9 | - | −3.1 | −7.2 |
Δ with MRA (%) | −4.9 | −5.6 | −5.3 | |||
Δ with GRC (%) × MRA (%) | −7.9 | −11.8 | ||||
Volume heat capacity (MJ/m3·K) 1 | 1.864 | 1.839 | 1.828 | 1.781 | 1.771 | 1.768 |
cρ (kJ/m3·K) | 0.814 | 0.826 | 0.847 | 0.848 | 0.863 | 0.888 |
Δ with GRC (%) | - | 1.4 | 4.1 | - | 1.8 | 4.8 |
Δ with MRA (%) | 4.1 | 4.5 | 4.9 | |||
Δ with GRC (%) × MRA (%) | 6.0 | 9.1 |
NA mix | MRA mix | |||||
---|---|---|---|---|---|---|
Parameter/Differential | NAC | N10/0 | N25/0 | R0/50 | R10/50 | R25/50 |
λs (W/m·K) 1 | 2.345 | 2.303 | 2.223 | 2.310 | 2.256 | 2.186 |
Δ with GRC (%) | - | −1.8 | −5.2 | - | −2.4 | −5.4 |
Δ with MRA (%) | −1.5 | −2.0 | −1.7 | |||
Δ with GRC (%) × MRA (%) | −3.8 | −6.8 |
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Cantero, B.; Bravo, M.; de Brito, J.; Sáez del Bosque, I.F.; Medina, C. Thermal Performance of Concrete with Recycled Concrete Powder as Partial Cement Replacement and Recycled CDW Aggregate. Appl. Sci. 2020, 10, 4540. https://doi.org/10.3390/app10134540
Cantero B, Bravo M, de Brito J, Sáez del Bosque IF, Medina C. Thermal Performance of Concrete with Recycled Concrete Powder as Partial Cement Replacement and Recycled CDW Aggregate. Applied Sciences. 2020; 10(13):4540. https://doi.org/10.3390/app10134540
Chicago/Turabian StyleCantero, Blas, Miguel Bravo, Jorge de Brito, Isabel Fuencisla Sáez del Bosque, and César Medina. 2020. "Thermal Performance of Concrete with Recycled Concrete Powder as Partial Cement Replacement and Recycled CDW Aggregate" Applied Sciences 10, no. 13: 4540. https://doi.org/10.3390/app10134540
APA StyleCantero, B., Bravo, M., de Brito, J., Sáez del Bosque, I. F., & Medina, C. (2020). Thermal Performance of Concrete with Recycled Concrete Powder as Partial Cement Replacement and Recycled CDW Aggregate. Applied Sciences, 10(13), 4540. https://doi.org/10.3390/app10134540