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See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/281102581 Recycled Aggregate Characterization Methods_Presentation Conference Paper August 2015 CITATIONS READS 0 87 1 author:

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See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/281102581

Recycled Aggregate Characterization Methods_Presentation

Conference Paper · August 2015

CITATIONS READS

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1 author: Some of the authors of this publication are also working on these related projects: Use of CDW as Raw Material View project A book on recycling of recycling of building materials. Very little about waste management and very much about processing and building materials. View project Anette Mueller IAB - Institut für Angewandte Bauforschung Weimar GmbH

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Institut für Angewandte Bauforschung Weimar gemeinnützige GmbH

Recycled Aggregate Characterization Methods

  • Prof. Dr.-Ing. habil. Anette Mueller

IAB Weimar gGmbH Sao Paulo August 2015

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Construction and Demolition Waste and Recycling Materials in Germany: Quantities and sectors of reuse State of the Art of Quality Control: Methods and results on composition and granulometry Sensor Based Optical Methods: Future alternatives for control of composition and granulometry? Sophisticated Characterization

  • Recycled concrete aggregates as composite material
  • Construction and Demolition Waste as feedstock

Conclusions

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1 CDW and Recycling Materials in Germany

Amount of Construction and Demolition Waste from different sources

Bundesverband Baustoffe – Steine und Erden e.V. Monitoringberichte 1996-2012

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Amount of material reused in different sectors

TV-Foto/Archiv: Gabi Vogelsberg

CDW for filling Price: giving away for free

Bundesanstalt fuer Strassenwesen: Jahresbericht 2009/2010. http://www.stadtentwicklung.berlin.de/umwelt/abfall/rc-beton/

1 CDW and Recycling Materials in Germany

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2 State of the Art of Quality Control

Technical Standards on

  • Reuse of asphalt in road construction
  • Reuse of recycled concrete aggregates

in road construction

  • Reuse of recycled concrete as

aggregate in structural concrete Environmental Standards on

  • Reuse of tar containing asphalt
  • Permitted content of leachable substances in dependence on site

conditions

P

> 1 m

RC with minimum leachable matter Permeable layer

P

> 1 m

RC with low/medium con- tent of leachable matter Impermeable layer

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Composition Granulometric parameters Physical parameters Reuse as base course material in road construction Material composition Finely divided organic constituents Particle size distribution Particle shape Content < 0.063 mm Content of oversize Portion of crushed particles Water content Density Proctor density Resistance to abrasion Freeze/thaw resistance Reuse as recycled concrete aggregate Material composition Lightweight organic constituents Content of − water-soluble chloride − acid-soluble chloride − water-soluble sulfate − acid-soluble sulfate Total sulfur content Particle size distribution Particle shape Content < 0.063 mm Water absorption Density Resistance to abrasion Freeze/thaw resistance

Technical standards for recycled aggregates 2 State of the Art of Quality Control

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Material composition Method: Hand sorting of the fraction > 4 mm

Hand sorting of ore acc. to Agricola 1556

Percentage passing = 100*M2/(M1+ M2) M2 M1 W L Particle size and shape Method: Screening Method: Particle shape gauge Shape Index = 100*ML/W>3/Mtotal 2 State of the Art of Quality Control

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Material composition Particle size Quantity of sample for reliable results Max. size [mm] Sample mass [kg] 32 50.9 16 36.0 8 25.5 4 18.4 Threshold [mass-%] ≤ 0.2 ≤ 5 ≤ 10 Sample mass [kg] 83.9 3.2 1.5 Number of particles 4/8 + 8/45 122,054 + 13,832 4,648 + 527 2,201 + 249

Diederich, D.: Recycling R'13, Weimar 2013.

2 State of the Art of Quality Control

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Results on composition taken from quality control protocols of base course materials

as high as possible ≤ 30 mass-% ≤ 30 mass-% ≤ 5 mass-% ≤ 1 mass-% ≤ 0.2 mass-%

  • Material fulfils the requirements
  • Considerable differences in performance over- or undervaluation
  • Faction < 4 mm is not detected

2 State of the Art of Quality Control

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Results taken from quality control of material for recycled aggregate concrete

Type I/Type II ≥ 90 resp. ≥ 70 mass-% ≤ 10 resp. ≤ 30 mass-% ≤ 1 mass-% ≤ 1 resp. ≤ 2 mass-% ≤ 2 cm³/kg

  • Material fulfils the requirements
  • No clear declaration of content either of concrete aggregates or of virgin

aggregate recycling without recycled aggregates possible 2 State of the Art of Quality Control

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Results on particle sizes taken from quality control of base course material

Percentage passing x: particle size [mm] xmax: maximum particle size [mm] n: distribution exponent [-]

  • Material fulfils the requirements
  • Particle size distribution follows the

Gates-Gaudin-Schuhmann-Function

  • Material specific influences undetec-

table under industrial conditions

xmax= 32 mm, n = 0.4 xmax= 56 mm, n = 0.55

2 State of the Art of Quality Control

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3 Sensor Based Optical Methods as Alternative

http://www.haver-partikelanalyse.com/formanalyse-von-partikeln/

Sensor based optical methods as future alternative for control of composition and granulometry?

Mogensen GmbH & Co. KG, Wedel, Germany.

Combination of optical measurement of color, NIR spectrum (available) and size, shape (available)

  • Size, shape, color, and NIR spectra

material composition

  • Size and shape

particle size distribution, particle shape index

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Detection of kind of material: Investigations of identification by means of near infrared spectra

Rubble of aerated auto- claved concrete Gravel Concrete Calcium silica brick Lightweight concrete Clay brick Masonry rubble Pure AAC Concrete rubble ~ 1930 nm ~ 1430 nm

Escher, M.: Diplom Thesis, Weimar 2010.

3 Sensor Based Optical Methods as Alternative

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Impact crusher - cubic particle Jaw crusher - splintery and platy particles

  • Defined as diameter of circle with equal area
  • Cubic particles: Good agreement
  • Platy particles: Correction necessary

Detection of particle size

Stark, U.; Mueller, A.: AufbereitungsTechnik 45 (2004) 6, S. 6 - 16.

3 Sensor Based Optical Methods as Alternative

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Detection of particle shape

  • Defined as ratio length (Feret diameter)

to width (maximum secant)

  • Ratio xFe/xS of particles generated with

the jaw crusher higher than with the impact crusher

  • Correaltion between shape index SI and ratio xFe/xS

x

xFe xS

Direction of measurement

Stark, U.; Mueller, A.: Beton (2006) 9, S. 390 – 397.

3 Sensor Based Optical Methods as Alternative

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Automated quality assurance of material composition, particle size and shape as future option for recycling? Advantages/Disadvantages

  • Sufficient large sample mass during reasonable time measurable
  • Higher frequency of quality control
  • No subjective influences, especially on detection of kind of material
  • Mass of material fractions not directly measured but calculated from

granulometric parameters and typical densities

  • Fraction < 4 mm not measurable

Research for deepening of knowledge is required! 3 Sensor Based Optical Methods as Alternative

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4 Sophisticated Characterization

Civil engineer approach Recycled concrete aggregate as composite material Mortar Composite Pure aggregate

Arguments against civil engineer approach:

  • Counterparties in concrete are cement

paste and aggregates (and ITZ), not mortar and aggregates

  • Cement paste content in mortar can vary
  • Mechanical properties of mortars are not

far from concrete

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4 Sophisticated Characterization Material scientist approach Pure aggregate Cement paste Composite

Clear characterization of recycled concrete aggregates by the properties of the main components (natural aggregates + cement paste) and the content of the cement paste

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4 Sophisticated Characterization As acid soluble content:

  • Moebius, Schnell/2001: Solubility in hydrochloric acid (10%) similar to

Standard DIN 52170

  • Engelsen et al./2009: Solubility in concentrated nitric acid similar to

Standard Nord Test Build 437

  • Weimann/2009: Solubility in hydrochloric acid (10%) similar to Standard

DIN 52170

  • Belin et al./2014: Solubility in nitric acid solution (1/50)

As difference of the quartz content up to 100%:

  • Florea, Brouwers/2013: Quartz content by phase transition of α-SiO2 to β-

SiO2 measured by thermogravimetric (TG) and differential scanning calorimetry (DSC) Methods for determination of cement paste content

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4 Sophisticated Characterization Comparison of cement paste content measured with the different methods

  • Similar results and trends for the dependency of the cement paste

content on the particle size

  • Both methods not suitable for concrete with calcitic aggregates
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21 BAST Jahrbuch 2008

4 Sophisticated Characterization Binary state diagram for recycled concrete aggregates

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22 BAST Jahrbuch 2008

4 Sophisticated Characterization Effects of “old” cement paste

  • Increase of CSH-phase content and porosity
  • Decrease of compressive strength and modulus of elasticity

Further properties depending

  • n paste content
  • Workability
  • Shrinkage and creep
  • Durability

Points: Measured values of 19 authors Lines: Calculated on the basis of the following assumptions

  • Additional porosity ~ 0.5 vol-%

in case 1 or ~ 3 vol-% in case 2

  • 1 vol.-% porosity results in

a strength loss 3 - 4 N/mm²

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Construction and demolition waste as feedstock

4 Sophisticated Characterization State of the art Recycling in a material conversion

  • process. Specific changes in the

chemical and mineralogical compo- sition for generating new product features. Reuse by utilizing the mechanical properties without transformation of the chemical and mineralogical composition. Future developments First assessment of possible applications based on

  • Ternary systems for “chemical” manufactured building

materials like cement clinker, clay brick, rockwool, expanded clay etc.

  • Chemical composition of recycled materials

http://www.keller.de/ www.steine-und-erden.net > 2008 > 1/08 http://www.cn-consulting.de/

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4 Sophisticated Characterization “Cement” ternary system

  • Fields of cementitous materials
  • Distribution of pure building materials

Clay brick as Al2O3 “supplier” for cement clinker production Clay brick as raw material for production

  • f artificial puzzolans

Concrete with calcitic aggregates as CaO “supplier”

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“Ceramic” ternary system 4 Sophisticated Characterization

  • Fields of different products
  • Distribution of pure building materials

(Aerated autoclaved concrete as raw material for glass) (Clay brick as raw material for brick) Clay brick as raw material for expanded clay

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Recycled materials in the “cement” ternary system

Masonry rubble as Al2O3 “supplier” for cement clinker production Masonry rubble as raw material for production

  • f synthetic puzzolans

Concrete rubble as SiO2 “supplier”

Technology for activation must be developed 4 Sophisticated Characterization

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Recycled materials in the “ceramic” ternary system

Masonry rubble as raw material for expanded clay

Existing technology must be adapted, suitable expanding agents must be found 4 Sophisticated Characterization

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Lightweight aggregates (LWA) from masonry rubble Expanding agent Product: Lightweight aggregates

Mischen Mixing + Shapening Pelletiermixer Thermal treatment Rotary kiln

Raw material

Pretreatment Crusher/Screen Grinding Ball mill

 Hamish John Applepy  Hamish John Applepy

Technology 4 Sophisticated Characterization

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3 % SiC 0.62 g/cm³ 1 % SiC 0.99 g/cm³ 0 % SiC 1.8 g/cm³

Achieved expansion 4 Sophisticated Characterization Achieved homogenization

∆ = 750 kg/m³ ∆ = 145 kg/m³

Input material Product

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Mechanical properties of concretes made of LWA from masonry rubble

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4 Sophisticated Characterization

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LWA from masonry rubble Expanded clay

Production of concrete blocs Production of concrete elements

TBR Technologiezentrum GmbH&Co.KG Bernburg Fenger Kies + Beton Kropstädt

4 Sophisticated Characterization

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Quelle: Reinhold, 2001 32

Primary raw material consumption → decrease from 100% (reference material expanded clay) to 5% (LWA from masonry rubble) Process heat consumption → decrease from 100% (reference material expanded clay) to 83% (LWA from masonry rubble)

SA EA 0.164 t Water for shapening

0.07 t Lost of ignition 1.22 t Green, wet granulates 1 t LWA 0.99 t Masonry rubble 0.164 t Water

Primary raw material

EC: Expanded clay LWA: Lightweight aggregate [kJ/kg EC] [kJ/kg LWA] Heating processes 1443 1225 Endothermic chemical processes Evaporation of moisture 659 391 Dehydration of clay minerals 241 Decomposition of CaCO3 67 238 Decomposition of CaSO4 37 Exothermic chemical processes 105 Sum 2305 1891

4 Sophisticated Characterization

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Construction and Demolition Waste is the biggest waste stream in Germany. Aggregates from CWD are characterized by wide variations

  • f composition and physical properties.

With the currently applied methods, the quality is not adequately monitored. With new sensor-based methods, both the frequency of testing as well as the reliability of the results could be improved. The use of CDW as feedstock opens new fields of reuse. It needs further research but it is essential for the development of a true recycling economy. 5 Conclusions

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An uncomplete List of Future Research How can the physical law that during the comminution fine fractions are generated, be tricked? What happens during storage? Partial or complete decontami- nation from soluble constituents like SO3? Carbonatisation? Use in road construction Material becomes finer by compaction? What about permabiliy? Durability? Reactions during use if partners (H2O, CO2, SO3) are available? Generation of ettringite or thaumasite? Heaving

  • f the top layer?
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Use in concrete What can be done to promote the use of coarse recycled aggregates in concrete? Do the fine fractions have really an hydraulic activity that can be bring back only by grinding? (We never found this.) Feedstock recycling of the fine fractions For which products CDW is suitable as raw material? Which processes can be adapted, which have to be developed? In which processes the use of CDW as feedstock has advantages in energy consumption?

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Homepage: www.iab-weimar.de E-Mail: a.mueller@iab-weimar.de

Thank you for your attention !

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