Biomaterials and Binders - Lanos

8/10/2019 Biomaterials and Binders - Lanos

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C. Lanos, F. Collet

UEB - LGCGM, Equipe Matriaux Thermo-Rhologie

INSA-IUT, Rennes

France

Mechanical properties

of hempcrete

Biomaterials & Binders for Construction Hemp, Lime, WoodEuropean workshop in Darmstadt, 2122 !o"em#er 2$11


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Hempcrete samples


Mix proportioning influences

Summary


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Representative size

Hempcrete samples

Mineral binders

- Lime

- Portland cement

- Belite cement

- Plaster-

Hemp shiv

- With fibres

- Without fibres

Representative

size of sample ?

7 x D = 14 cm

300/m3 kg < apparent density < 800 kg/m3

0,3 < shiv+binder volume fraction


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Production method

Hempcrete samples

Real mixers

Laboratory mixers

- Wet mix

- Dry mix

Hobart type mixer (20 litres)- mix of the paste

- add of aggregate

mixing duration following the used binder

( typically 2 min)


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Uses of hempcrete

On site moulding

Precasting blocks

Spraying

Water content adjustment to ensure flow ability


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Hempcrete samples

Samples sizesReal size sample : box

30 cm30 cm

16 cm

Usable for :

- sprayed concrete

- moulded concrete

Respect of loading direction


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Hempcrete samples

Real size sample : wall

Prismatic samples 14x14x70 cm3

For flexural tests For compression test

Thickness = 17 cm Sample are take of the wall

Usable for :

- sprayed concrete

- moulded concrete


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Cylindrical sample

D = 16 cm H = 32 cm 3 layers with compaction

Usable for :

- moulded concrete

- shiv binder validation

Hempcrete samples


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Closed mould

6-28 days at room temperature (following the binder)

Removing of mould

drying at 23 C and 55 HR

Mass loss survey

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0 10 20 30 40 50 60

t (j)

masse chantillon (kg)

lime

2000

2500

3000

3500

4000

4500

5000

5500

6000

0 20 40 60 80 100 120 140 160

dmoulageHydraulic binder

Hempcrete samples

Curing conditions

Sample mass (g)

Sample mass (g)


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Imposed displacement : 5 mm/min

progressive cyclic loading(example : 1,5 mm, 3 mm, 5 mm, 10 mm and 50 mm)

final strain > 15%


MethodSample surface are straightened (by sawing)

Load cell capacity : 50 kN

(INSTRON 400 kN with large rigidity)

Output:

stress : F/So

strain : h/hoservo-mechanical

testing systems


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typical behaviour of hempcrete

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

,

0 0,05 0,1 0,15 0,2 0,25

def (m/m)

strain stress curves

Data analysis:- Maximum stress

- Compressive modulus

- Residual strength

- strain at maximum stress

Sample analysis

- Localization of compaction

- failure

0,3 < shiv+binder volume fraction < 0,55


Without compaction

Chamoin (2012)

c (MPa)

(m/m)


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strain stress curves

Data analysis:

- Compaction effect- Compressive modulus


Homogeneous strains

Compaction of sample

With compaction: 0.1 to 2.9 MPa

0,6 < shiv+binder volume fraction < 0,8

NGuyen (2010)

c (MPa)

(%)


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Repeatability


Lime hempcrete 700 kg/m3

Links with the sample density repeatability

c (MPa)

(m/m)


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OutputFailure type (lime hempcrete 450 kg/m3)

Without fibers With fibers


Lime hempcrete

710 kg/m3cement hempcrete550 kg/m3

ANR Btonchanvre (2010)


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Loading direction and compaction effects

Demi-prouvette horizontale Demi-prouvette verticale Bloc entier


Various loading direction



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Compression strength versus density

y = 3E-05x2,62

R2= 0,92

y = 0,0082x1,83

R2= 0,43

0

200

400

600

800

1000

200 300 400 500 600Masse volumique (kg m

-3)

Rsistancelacom

pression(kPa)

Matriau A (pr. entire)

Matriau A (demi-pr. horizontale)

Matriau A (demi-pr. verticale)

Matriau B (pr. entire)

Matriau B (demi-pr. horizontale)

Matriau B (demi-pr. verticale)

Matriau C (pr. entire)

Matriau C (demi-pr. horizontale)

Matriau C (demi-pr. verticale)

Courbe modle d'Elfordy et al. (2008) = 0(/0)2

density

Compressionstren

gth


Sprayed lime hempcrete

Moulded lime hempcrete



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compacted lime hempcrete


Nguyen (2010)

density

Compressionstren

gth


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0

0,05

0,1

0,15

0,2

0,25

0,3

0 0,02 0,04 0,06 0,08 0,1 0,12 0,14 0,16 0,18 0,2

Rc

def (m/m)

0

0,02

0,04

0,06

0,08

0,1

0,12

0,14

0 0,002 0,004 0,006 0,008 0,01 0,012 0,014 0,016 0,018 0,02

Rc (MPa)

def (m/m)

36 MPa

14 MPa

Distinction between :

- apparent modulus 10 150 MPa- elastic modulus 10 300 MPa

Moduli


c (MPa)

(m/m)

c (MPa)


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Compression strength evolution


Crzo (2005)


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0

0,1

0,2

0,3

0,4

0,5

0,6

1 10 100 1000

j

Rc cube (MPa)

Compression strength evolution


1/3plaster 2/3 lime hempcrete

Quick setting

Lime carbonation effect


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Influence of binder content

Increase of

binder

content

Crzo (2005)


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Influence of fibres type, carbonation, binder type

0,00

0,10

0,20

0,30

0,40

0,50

0,60

0,70

0,80

0,90

350,00 400,00 450,00 500,00

F1-NC

F1-C

F2-NC

F2-C

F3-NC

F3-C

F4-NC

F4-C

c (MPa)

(kg/m3)

Shiv without fibres

Shiv with fibres

Chamoin (2012)


100 % lime

70 % plaster

30 % lime

C = carbonated

NC = non carbonated


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0,00

0,10

0,20

0,30

0,40

0,50

0,60

0,70

0,80

0,90

0,00 20,00 40,00 60,00 80,00 100,00 120,00 140,00



F1-NC

F1-C

F2-NC

F2-C

F3-NC

F3-C

F4-NC

F4-C

c (MPa)

apparent (MPa)

Shiv without fibres

Shiv with fibres

Chamoin (2012)

Compression strength versus apparent modulus

C = carbonated

NC = non carbonated


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0,0000

0,0050

0,0100

0,0150

0,0200

0,0250

0,0300

0,00 20,00 40,00 60,00 80,00 100,00 120,00 140,00



F1-NC

F1-C

F2-NC

F2-C

F3-NC

F3-C

F4-NC

F4-C

(c) (m/m)

Shiv without fibres

Shiv with fibres

Chamoin (2012)

strain at maximum compression strength versus apparent modulus

Carbonation effectC = carbonated

NC = non carbonated

apparent (MPa)


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Conclusions

Hempcrete :

compressible material

low compression strength 0,2 3,5 MPa

better strengths after compaction

links between mechanical parameters:large influence of density

low elastic modulus < 300 MPa

large strain

Interesting post pick strengths


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Documents

Biomaterials and Binders - Lanos