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6 th International Conference on Sustainable Solid Waste Management The alkali activation of construction and demolition waste (CDW) components for stabilization purposes Marco Bassani (1) , Luca Tefa (1) , Paola Palmero (2) (1) Department of

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The alkali‐activation of construction and demolition waste (CDW) components for stabilization purposes

6th International Conference on Sustainable Solid Waste Management

The Cultural Center former Ursuline School ‐ Naxos, Greece

13th June 2018

Marco Bassani(1), Luca Tefa(1), Paola Palmero(2)

(1) Department of Environment, Land and Infrastructures Engineering (2) Department of Applied Science and Technology,

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Introduction

CONSTRUCTION AND DEMOLITION WASTE (CDW) Waste material produced in the process of construction, renovation, or demolition of buildings and infrastructures.

(US EPA, United States Environmental Protection Agency)

  • concrete
  • bricks and tiles
  • asphalt
  • natural aggregates and excavated soil
  • impurities (metals, wood, glass, plastic)

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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Natural aggregates Concrete Bricks and tiles Asphalt

Production and recycling EU‐28 (2014): 868 million of tons of CDW per year (1/3 of total waste generated in EU) Average recycling rate: 46 %

(European waste statistics)

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Surface Base Subbase Subgrade Embankment

Motivation and interest

  • recycling and re‐using policies of Europe
  • increasing demand for sustainable infrastructures
  • reduction of exploitation of natural resources
  • environmental and economic benefits

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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CDW AGGREGATE USES Improving performances in terms of strength, stiffness, and durability

Stabilization techniques

Alkali‐activation From waste to resource…

  • no addition of binders
  • addition of cementitious binders
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NA RC BT RA NA RC RA BT

Research objective

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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Alkali‐activation

  • f CDW fines

CDW aggregates in 4 components:

  • RC (recycled concrete)
  • RA (recycled asphalt)
  • BT (bricks and tiles)
  • NA (natural aggregates)

UND

  • UND

(undivided CDW) Binding attitude exhibited by the most reactive phase Coarse particles d>0.125 mm Fine particles d<0.125 mm

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Fines characterization

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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Particle size distribution, density Physical characterization X‐ray diffraction Chemical analysis POWDERS

X‐ray detector Specimen Diffracted X‐ray X‐ray emitter

Smith (1993). Foundations of materials science and engineering. McGraw‐Hill.

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X‐ray diffraction test (XRD)

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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Mineral phases RC RA BT NA UND Aluminosilicates (%) 23.3 29.7 63.6 30.1 56.8 Minerals from mica group (%) 15.2 11.9 30.3 n.a. 22.7 Carbonates (%) 26.0 13.9 6.1 17.2 11.8 Quartz (%) 9.1 9.9 22.2 8.5 14.7

XRD patterns

5 10 15 20 25 30 35 40 45 50 55 60 65 70

Intensity (a.u.) 2(°)

Q - Quartz C - Calcite G - Gypsum E - Enstatite Ph - Phengite L - Lizardite Cl - Clinochlore

Q Q C Q Q Q C Q C Q C CQ Q Q C QQ Q Q G E Al Ph Ph Ph Ph L L Cl Cl E E C C Q Q C C Q 10000

5 10 15 20 25 30 35 40 45 50 55 60 65 70

Al

Intensity (a.u.) 2(°)

Q - Quartz H - Hematite Al - Albite Cr - Cristobalite M - Muscovite C - Calcite

10000 Q Q Q Q Q Q Q Q Q Q Q QQ Q Q H H H H Cr Al Al Al Al M M M C

RC BT Semi‐quantitative phase analysis Aluminosilicates in all components (especially BT and UND) essential for alkali‐activation process.

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Alkali‐activation of fines

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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+

  • 0.4

Mixing

  • room temperature
  • 3, 7, 28 days

Casting

(Prisms 20x20x80 mm)

  • RC, RA, BT, NA
  • UND

CDW fines 2 size fractions:

  • d < 0.063 mm
  • 0.063 mm ≤ d < 0.125 mm

Activating alkaline solution (AAS)

(10% NaOH + 29% Na2SiO3 + 61% H2O)

3 concentrations:

  • 100%  AAS_100%
  • 75%  AAS_75%
  • 50%  AAS_50%

15 combinations

  • f mixtures

Curing

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Characterization of mixtures

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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F F

3‐point flexural tests Compressive tests MIXTURES Strengths of hardened products Viscosity Properties of fresh mixtures Mechanical properties Brookfield viscometer

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Viscosity of fresh mixtures

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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20000 40000 60000 80000 100000 120000 140000 160000 180000 10 100 Viscosity (cP) Speed (rpm) RC RA BT NA UND 200 20000 40000 60000 80000 100000 120000 140000 160000 180000 10 100 Viscosity (cP) Speed (rpm) RC RA BT NA UND 200 20000 40000 60000 80000 100000 120000 140000 160000 180000 10 100 Viscosity (cP) Speed (rpm) RC RA BT NA UND 200

AAS_50% AAS_75% AAS_100%

  • viscosity decreases with revolution speed (non‐Newtonian)
  • viscosity increases with AAS concentration
  • different viscosity for each components
  • highest values for UND and RC, lowest one for NA

Workability during compaction

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Flexural strength

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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RC RA BT NA UND 3 days 0.07 0.05 0.12 0.15 0.06 7 days 0.11 0.09 0.20 0.16 0.08 28 days 0.23 0.37 0.46 0.26 0.15 0.0 1.0 2.0 3.0 4.0 5.0 6.0 Flexural strength (MPa) RC RA BT NA UND 3 days 0.60 0.00 0.38 0.33 0.40 7 days 1.00 0.15 0.72 0.40 0.99 28 days 1.30 0.37 1.72 1.04 1.80 0.0 1.0 2.0 3.0 4.0 5.0 6.0 Flexural strength (MPa) RC RA BT NA UND 3 days 0.00 0.00 0.33 0.35 0.83 7 days 0.00 0.63 0.38 0.42 0.98 28 days 0.09 4.52 0.99 0.51 4.96 0.0 1.0 2.0 3.0 4.0 5.0 6.0 Flexural strength (MPa)

AAS_50% AAS_75% AAS_100%

  • improvement of flexural strength (σf) with curing time
  • σf strongly influenced by the AAS concentration and the component of CDW
  • σf of RC, BT, NA higher with AAS_75%; RA, UND more active with AAS_100%
  • UND shows the highest σf (for different curing time)  5.0 MPa
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Compressive strength

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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RC RA BT NA UND 3 days 0.34 0.29 0.50 0.43 0.35 7 days 0.47 0.31 0.62 0.45 0.42 28 days 0.61 0.60 0.94 0.58 0.47 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 Compressive strength (MPa) RC RA BT NA UND 3 days 1.75 0.00 1.53 1.07 1.48 7 days 2.63 0.45 2.10 1.33 2.68 28 days 3.57 1.24 4.59 2.51 5.66 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 Compressive strength (MPa) RC RA BT NA UND 3 days 0.00 0.00 2.00 1.33 3.41 7 days 0.00 1.13 2.51 1.52 5.38 28 days 0.23 7.85 4.32 2.08 12.79 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 Compressive strength (MPa)

AAS_50% AAS_75% AAS_100%

  • similar behavior of flexural strength results (σc≈ 3 σf)
  • σc of samples with AAS_75% and AAS_100% >> AAS_50%
  • σc of RC and NA higher with AAS_75% than AAS_100%
  • BT and UND  rich of aluminosilicates  highest σc
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Conclusions

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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Presence of aluminosilicate phases in all components (RC, RA, BT, NA, UND) potentially reactive in alkaline environment Chemical analysis Mechanical properties Key role of concentration of AAS both in workability of fresh mixtures and in strength development Best mechanical strengths for UND component (calcium‐ reach and alumina‐silicate phases  geopolymers and C‐S‐H) Huge variability in mechanical behavior AAS+CDW powders (d<0.125 mm) increase strengths without any thermal treatment and binder addition

  • better performances for BT and UND

(aluminosilicate and mica‐group phases)

  • σc and σf increase with curing time
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Future perspectives

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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From mixtures of fine particles… … to stabilized CDW aggregates

  • lab scale
  • full scale application
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POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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Thank you!

The alkali‐activation of construction and demolition waste (CDW) components for stabilization purposes

Marco Bassani(1), Luca Tefa(1), Paola Palmero(2)

(1) Department of Environment, Land and Infrastructures Engineering (2) Department of Applied Science and Technology

luca.tefa@polito.it

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Additional information (I)

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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  • Particle size distribution

10 20 30 40 50 60 70 80 90 100 0.1 1 10 100 1000 Cumulative frequency (%) Particle size (μm) RC RA BT NA UND

d < 0.063 mm

10 20 30 40 50 60 70 80 90 100 0.1 1 10 100 1000 Cumulative frequency (%) Particle size (μm) RC RA BT NA UND

0.063 mm ≤ d < 0.125 mm

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Additional information (II)

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

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  • Density

Component Particle size [m] ρp [Mg/m3] ρb [Mg/m3] ν (%) RC <63 2.580 1.945 24.6 63 ÷ 125 2.687 1.953 27.3 RA <63 2.424 1.940 20.0 63 ÷ 125 2.347 1.990 15.2 BT <63 2.763 2.010 27.3 63 ÷ 125 2.722 1.946 28.5 NA < 63 2.726 1.987 27.1 63 ÷ 125 2.710 2.025 25.3 UND < 63 2.640 1.963 25.6 63 ÷ 125 2.673 1.963 26.5

Particle density Bulk density Rigden porosity

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Additional information (III)

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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  • X‐ray diffraction output pattern

5 10 15 20 25 30 35 40 45 50 55 60 65 70

D At Cd E E E At At At At At At At

Q - Quartz C - Calcite At - Antigorite E - Enstatite Cd - Cordierite Cl - Clinochlore M - Muscovite D - Diopside

C C C C C C C C Q Q Q Q Q Q Q Q Q Q Q Q Q Q

Intensity (a.u.) 2(°)

10000 Q E Cd Cl M M

RA

5 10 15 20 25 30 35 40 45 50 55 60 65 70

DE

Q - Quartz C - Calcite Cd - Cordierite E - Enstatite L - Lizardite Cl - Clinochlore D - Diopside I - Illite

Intensity (a.u.) 2(°)

Q C Q C Q C Q Q Q C Q C Q Q C Q Q C Q Q Q Q 10000 Cd Cd Cd E E E E I I D Cl Cl Cl Cl L L

NA

5 10 15 20 25 30 35 40 45 50 55 60 65 70

Intensity (a.u.) 2(°)

Q - Quartz C - Calcite Al- Albite G - Gladiusite Ph - Phengite Cl - Clinochlore A - Antigorite D - Diopside

Q Q C C Q Q C Q Q C Q CC Q Q QC Q C Q Q Q Q Al Al Al Al Al G Cl Cl Cl Ph A

UND

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Additional information (IV)

POLITECNICO DI TORINO The alkali‐activation of CDW components for stabilization purposes Luca Tefa

6th International Conference on Sustainable Solid Waste Management, Naxos. Greece ‐ 2018

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  • Proportion of components in the alkaline solution

AAS_75% AAS_100% AAS_50%