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Barbara PIETRUSZKA 1 , Michał GOŁĘBIEWSKI 2 , Paweł L ISOWSKI 1

1 Building Research Institute, Department of Thermal Physics, Acoustics and Environment, 21 Ksawerów Street, 02-656 Warszawa, Poland

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Barbara PIETRUSZKA 1 , Michał GOŁĘBIEWSKI 2 , Paweł L ISOWSKI 1

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  1. 1 Building Research Institute, Department of Thermal Physics, Acoustics and Environment, 21 Ksawerów Street, 02-656 Warszawa, Poland 2 Warsaw University of Technology, Faculty of Architecture, Department of Structural Design, Building Technology and Technical Infrastructure, Koszykowa Street, 00-659 Warszawa, Poland Barbara PIETRUSZKA1 , Michał GOŁĘBIEWSKI2, Paweł LISOWSKI 1 Characterization of hemp-lime bio-composite

  2. Content • Introduction • Materials and samples • Experimentalpart • Results • Conclusions 1402

  3. HEMPCRETE(as infillmaterial) = HEMP SHIV + LIME BINDER + WATER • a non-load-bearing material, • low mechanical strength: 0.05-0.9 MPa, • medium densitymaterial, • good insulating properties:0.08-0.12 W/(mK) • biological and chemical corrosion resistance, • good fire resistance, • high vapour permeability(4-30) 1402

  4. Construction techniques • Forming of monolithicwalls by tamping in 2-sided formwork, • Forming monolithicwalls by spraying on 1-sided formwork, • Bricklayingusingprefabricadedbricks and blocks, • Buildingwith a use of prefabricatedwallpanels. 1402

  5. Use in construction • - lowdensity mix (~ 220 kg/m3) for roof/ risedfloorinsulation, • - medium density mix for newwalls and insulation of existingwalls (~ 330 kg/m3), • - veryhigh density mix for external/internalplasters (~ 900 kg/m3). PHOTO: „Characterisation of Hemp – lime as a CompositeBuildingMaterial” by Edward Alexander Joseph HIRST 1402

  6. Applications • In newbuildings as infill materials for walls with woodenorsteelstructuralframemostly in small residential buildings and single-family houses, or for walls in biggerbuildings with reinforcedconcretestucture. • Renovationof historicalbuildings: cavitiesfillings and/orcomplete exchange of infills in wattle and daubstructures. 1402

  7. Materials and samples Two different mixes were prepared – both using hemp shiv „Białobrzeskie” cultivated and processed in the north-east region of Poland (the material has not declared functional properties for construction purposes): • mix T - a special binder for hempcrete production „Tradical PF 70” was used (75% of hydrated lime, 15% of hydraulic lime, 10% pozzolans and other minor additives) • mix B- so-called „builder’s mix” of commonly available binders was used (75% of hydrated lime, 15% of hydraulic lime and 10% of cement CEM II/B-V 42,5 N) • Freshsamples were condictionedfor first 28 days (temperature 18ºC ± 2 ºC, relative humidity 90% ± 10%). Rest of the time samples were stored in temperature 23 ºC ± 2 ºC and relative humidity 55% ± 10% (90 days). 1402

  8. Characteristics of samples prepared for tests 1402

  9. Experimentalpart The experimental programme consisted of: • density, • mechanical strength, • thermal conductivity, • sorption (moisture/watercontent), • watervapour permeability tests. 1402

  10. Density measurement of samples(EN 1602) Before the test, the samples were dried at temperature 100 oC, next conditioned at temperature (23 ± 2) oC and relative humidity below 5% until a constant mass of the sample was obtained. Five samples of every type of material were tested and the mean values of density for each type of material are presented. Compressive strength tests(EN 12390-4)Before the test, the samples were conditioned at temperature (23 ± 2) oC and relative humidity about 50%. Three samples of every type of material were tested and the mean values arepresented. 1402

  11. Thermal conductivity (EN 12667) • Before the test samples were conditioned to achieve a constant weight under constant temperature (23 ± 2) °C and relative humidity 0, 50, 80 and 90%. • Measurements of thermal conductivity  were carried out in the steady-state conductions by the hot plate method, with a FOX 314 apparatus. The measurements were made at the average sample temperature of 10 oC, the difference in temperature at the sample thickness of 20 K and heat movement from bottom to top, on samples with dimensions (300 x 300 x 100) mm. • Three samples of very type of material were tested and the mean values of thermal conductivity for each type of material are presented. 1402

  12. Watercontent/ sorption(EN ISO 12571 ) • Samples were placed under constant temperature conditions of 23 °C and relative air humidity of 0%, 50%, 80% and 90%, respectively until their mass were stabilized. • Measurements of mass change were made every 24 hours. • Five samples of every type of material were tested and the mean values for each type of material are presented. 1402

  13. Water vapour permeability(EN 12086) • The samples were conditioned at a temperature of (23 ± 5) oC and relative humidity (50 ± 5)% until the mass stabilized in three consecutive weighing (change in mass within ± 5%) • The samples, diameter 128 mm, thickness 100 mm, were placed in metal dishes on the bottom of which a drying agent (CaCl2) was used. • Measurements of the change in weight were recorded at an interval of 12 hours. • The tests were terminated when five consecutive changes in the mass per unit time were constant and housed within a tolerance of ± 5% of the average for each sample tested. • Five samples of every type of material were tested and the mean values of water vapour diffusion resistance for each type of material are presented. 1402

  14. Results Pure hemp shiv (without binder) Hemp-lime bio-composite 1402

  15. Characteristics of hemp-lime bio-composite Pure hemp shiv (without binder) had the lowest thermal conductivity of 0.046 W m-1K-1(for a dry sample) and density92 kg/m3. 1402

  16. Characteristics of hemp-lime bio-composite All the hemp-lime compositesshowedrelatively low water vapour diffusion resistance factor µ, between 24 – 29. 1402

  17. Conclusions 1. The density of the hemp-lime composite and thermal conductivity are both determined by the content of hemp shiveand lime binder in the mixture. 2. Hemp-lime bio-composite images have shown quite a homogeneous structure. 3. The best compressive strength result was obtained for the T750 composite: 0.6 MPa. 4. Thermal conductivity depends on the material density (moisture content). The results for the tested samples varied in a range from 0.080 W m-1K-1 to 0.12 Wm-1K-1for a dry T550 and T750 material (90% RH), respectively. 5. All the hemp-lime compositesshowedrelatively low water vapour diffusion resistance factor µ(24 – 29) and may be appropriate materials for the external walls, when using the suitable external and internal plasters . 1402

  18. Barbara Pietruszka b.pietruszka@itb.pl 1402

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