Evaluation of hemp concrete thermal properties - PowerPoint Presentation

Slide1

Evaluation of hemp concrete thermal properties

2016 IEEE Smart World CongressWorkshop on Smart and Sustainable CityJuly 18th 2016 Billy SENG

SupervisorsCamille MAGNIONT (LMDC)Sandra SPAGNOL (PHASE)Sylvie LORENTE (LMDC)Slide2

Current

issues in construction industryBiosourced material’s impetus

2Energy consumption

Environmental

impact

Occupant’s

health

and

comfort

Insulating

Few

energy

consumption

for

manufacturing

RenewableCarbon storageGreenhouse gas balance : 35 kg(CO2)/m² storage (30 cm HC wall for 100 years)Local production

Hygrothermal regulationAdapted to retrofitting

Context

& Objectives

Conclusion

& Perspectives

Physical

properties measurement

HC: Hemp concrete

Thermal conductivity and capacity measurementSlide3

(2013 - )Refurbishment

of Rangueil’s campus11 Toulouse’s laboratoriesObjectives:Increase the users’ comfortReduce

the environmental impacts & the operational costs Perspective : use of biosourced material as instrumented walls in a new building3

Context

& Objectives

Conclusion

& Perspectives

Physical

properties

measurement

Thermal

conductivity

and

capacity

measurementSlide4

Study

MaterialPrecast hemp concreteCooperative work between LMDC & SEAC4

Hygrothermal transfers modelExperimental measurement:Material’s propertiesExperimental test (wall

scale): bi-climatic

chamber

Indoor/

outdoor

conditions

&

Initials

conditions

Indoor

&

wall

conditions

Heat

lossHealth & comfortDurabilityObjective: Prevision

of the hygrothermal behaviour of this precast hemp concrete

Hemp

+

Lime-

metakaolin

1

2

3

Context

& ObjectivesConclusion & Perspectives

Physical

properties

measurement

Thermal

conductivity

and

capacity

measurementSlide5

5

Hygrothermal

transfer modelExperimental measurement:Material’s propertiesThermal propertiesThermal conductivitySpecific heat

capacity

Hydric

properties

Vapour

permeability

Liquid

permeability

Sorption

isotherm

Physical

propertiesDensity and porosityAir permeabilityIssues: strong interdependencesTemperature/

Humidity Thermal properties

Hydric properties

Context

& Objectives

Conclusion

& Perspectives

Physical properties

measurementThermal conductivity and capacity

measurementSlide6

6

Apparent density ρapp

ρapp= 466 ± 25 kg/m³

Mass ratio x

i

x

hemp

=

0,12 ± 0,04

x

binder

= 0,88 ± 0,04

Context

& Objectives

Conclusion

& Perspectives

Physical

properties measurementThermal conductivity and capacity measurement

Total

porosity

calculation

εtot

ε

tot = 0,78 ± 0,05

Open

porosity

εopen

ε

open

= 0,76 ± 0,01 Slide7

7

Thermal conductivity λGuarded Hot Plate

Dry samples 15 cm x 15 cmHot WiredTransient method: evaluation of humidity impactSamples’ conditioning: dry, 50% HR, 65% HR and 95% HR

T

chaud

T

froid

Ech

.

Ech

.

e :

Thickness

(m)

q :

Heat

rate (W)

Δ

T :

Temperature

difference

(K)

S:

Sample

surface (m²)

Heat

rate

measurement

q

Temperature

measurement

T

Resistance

Thermocouple

q

  :

L

ineic

heat

flux (W/m)

t : Time (s)

Δ

T :

Temperature

increase

(K)

K : constant

Measurement

at T=10°C, T=23°C et T=40°C

6

samples

Context

& Objectives

Conclusion

& Perspectives

Physical

properties

measurement

Thermal

conductivity

and

capacity

measurementSlide8

8

Thermal conductivity λ=f(ρapp)

Literatureλ aerated concrete, dry = 0.1 W/(m.K) Context& Objectives

Conclusion

& Perspectives

Physical

properties

measurement

Thermal

conductivity

and

capacity

measurementSlide9

9

Thermal conductivity λ=f(T)

Context& ObjectivesConclusion & PerspectivesPhysical properties measurementThermal conductivity

and capacity

measurementSlide10

10

Thermal

conductivity λ=f(u)Model?Self-Consistent Scheme VS Linear regression?y = 0.2236x + 0.1322

Slide11

11

Heat capacity measurement cp

Indirect cp measurement through effusivity b measurement

Hot plane

Temperature

measurement

T

q

:

Heat

flux(W/m²)

t : Time (s)

T :

Temperature

(K)

ρ

app

: apparent dry

density

(kg/m³)

λ

: thermal

conductivity

(W/(

m.K

)

Ech

.

Context

& Objectives

Conclusion

& Perspectives

Physical

properties

measurement

Thermal

conductivity

and

capacity

measurementSlide12

12

Heat

capacity

measurement

c

p

Differential

Scanning

Calorimetry

DSC

DSC

blank

DSC

sample

DSC

sapphirTemperatureTime

Heat rate

1)

Blank



deviation

study

2) Reference (

Sapphir

)



Cp of a

known

material

3

)

Sample



Cp

of the

sample

reference

sample

Heat

rate signal (tension)

Issues :

small

quantities

of

material

(

≈10mg)

:

Representativeness

?



Compound :

hemp

& binder



Temperature

range 0-50°C

c

p,sample

;

c

p,sapph

:

Sample

&

sapphir

specific

heat

capacity

(J/(

kg.K

))

m

sample

;

m

sapph

:

Sample

and

sapphir

masses (g)

Context

& Objectives

Conclusion

& Perspectives

Physical

properties

measurement

Thermal

conductivity

and

capacity

measurementSlide13

13

Indirect cp measurement

through effusivity b measurement

c

p,hemp

= 1771 ± 300 J/(

kg.K

)

c

p,binder

= 874 ±

69 J/(

kg.K

)

xchen= 0,12 ± 0,04 xliant= 0,88 ± 0,04

cp,HC (DSC)= 985 ± 210 J/(kg.K) at T=20°C

Differential

Scanning

Calorimetry

DSC

b= 197 ± 16 W/(m².K. s

1/2)λ = 0,112 ± 0,007 W/(m.K) ρapp= 466 ± 25 kg/m³

c

p,HC

(hot-plane)

= 741 ± 230 J/(

kg.K

)

at

T=20°C

Heat

capacity

measurement

c

p

Literature

b= 155

W/(m².K. s

1/2

) (

Nozahic

2012)

b

= 213

W/(m².K. s

1/2

)

(

Samri

2013)

b

=286

W/(m².K. s

1/2

)

(Evrard 2008

)

Literature

c

p,HC

= 1560 J/(

kg.K

) (Evrard 2008)

c

p,HC

=

1000

J/(

kg.K

) (Collet 2004)

Literature

c

p

,

hemp

=

1517

J/(

kg.K

) (LNE)

c

p,biomass

= 1300-1500

J/(

kg.K

)

(Dupont et al., 2014

)

c

p,lime

-MK

= 900

J/(

kg.K

) (

Vejmelková

et al., 2011)

Context

& Objectives

Conclusion

& Perspectives

Physical

properties

measurement

Thermal

conductivity

and

capacity

measurementSlide14

14

Heat

capacity

measurement

c

p

Wet

heat

capacity

calculation

u: water content (kgwater

/kgmat)

Literaturecp,aerated

concrete, dry

= 850 J/(kg.K)

Context

& Objectives

Conclusion & Perspectives

Physical properties measurementThermal conductivity and capacity

measurementSlide15

15

Context& Objectives

Conclusion & PerspectivesPhysical properties measurementThermal conductivity and capacity measurementSEAC Hemp concrete blockAerated concrete

Thermal

conductivity

λ

(W/(

m.K

))

(dry state)

λ

=0,112

W/(

m.K

)

λ(u): regression, model?

λaerated concrete≈ 0,11 W/(m.K)Heat capacity cp (J/(kg.K)) (dry state)cp≈ 741 – 985 J/(kg.K)Cp(u) : calculation cp,aerated concrete ≈ 850 J/(kg.K)

Summary

and

comparison

…but

different

environmental assets.Slide16

Perspectives

16

Hygrothermal transfers modelExperimental measurement:Material’s propertiesExperimental test (wall scale): bi-climatic chamber

Indoor

&

wall

conditions

1

2

3

Thermal

properties

Thermal

conductivity

Specific

heat

capacityHydric

propertiesVapour permeabilityLiquid permeabilitySorption isotherm

Context

& Objectives

Conclusion

& Perspectives

Physical properties measurement

Thermal conductivity and capacity

measurementSlide17

17

Thank you for your attention