Environmental impact of construction Embodied energy New materials for construction desirable characteristics Building limes Pozzolans Hemp concrete

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2 Environmental impact of construction Embodied energy New materials for construction desirable characteristics Building limes Pozzolans Hemp concrete

3 EU Energy Performance of Buildings Directive EPBD (2002/91/EC). on building energy efficiency. intends to limit the use of fossil fuel energy and CO 2 emissions arising from buildings. came into force January 2003 ; to be implemented by the EU Member States January inspired by the Kyoto Protocol which commits the EU to reduce CO 2 by 8% by 2010 most effort has been concentrated into reducing operating system energy in buildings over their lifetime to improve energy efficiency. however, embodied energy of materials can be equivalent of several years of operational energy.

4 The construction industry is non- sustainable impact on the environment consumption of non- renewable natural resources both raw materials and fossil fuels production and transport generation of waste high CO 2 emissions- global warming & climate change New materials for construction Low energy to produce and transport (embodied) renewable, recyclable, energy efficient.

5 Properties vary on account of hydraulic strength: faster hardening and greater strengths Binder Hardening mechanism Hydraulicity Contraction coefficient Production temperature Clay dehydration Nil Medium ambient Gypsum Hydration (rapid hardening <15 minutes) Nil Nil 175 C Lime carbonation Nil High 900 C Hydraulic lime hydraulic set Low to high Mediumdepends C on hydraulicity Portland cement hydraulic set High Medium 1500 C Natural cements hydraulic set High Medium 1500 C

6 Choice of masonry mortar Strength of walls to use the full capacity of a high strength brick (>70 N/mm 2 ) a 3:1 (a:pc) is needed. for lower strength brick, lime can be used without strength loss. only special engineering applications need such strength! Unit strength N/mm2 Mix (OPC:lime: sand)* EN designation 10 1:2:9 iv :1:6 iii :1/4:3 i 70 or more * By volume 1:0:3 i

7 Building limes Air lime. Calcination of pure limestone. Hardens by carbonation- No hydraulic set. Seasonal. CL 90. CL 80. Ca(OH) 2 Hydraulic limes. Natural (NHLs) or Formulated (PFLs or FLs- can contain PC). Properties vary on account of hydraulic strength: Hardening speed; ultimate strengths; shrinkage; partial underwater set. Designation according to reactivity determined by strength development over time: NHL2/NHL3.5/NHL5- feebly, moderately, emminently hydraulic. Calcination of limestones containing SiO 2/ Al 2 O 3/ FeO.

8 LIME TECHNOLOGY

9 Pozzolans materials with amorphous SiO 2 or SiO 2 / Al 2 O 3 that react with Ca(OH) 2 in the presence of water to form cementitious hydration products calcium silicate hydrates and calcium silicate aluminate hydrates = hydration of PC clinker alter properties can result in faster setting times, higher mechanical strength, lower hydration and pozzolanic reactivity of pozzolan pastes

10 Pozzolans Blast- furnace slag, fly ash, silica fume, CKD, Industrial and agricultural by- products with pozzolanic activity Partial binder replacement (up to 60%!!!) significant economic and environmental benefits recycling waste reducing cement content in concrete, with the subsequent drop in energy consumption, non- renewable natural raw material consumption and CO 2 emissions,

11 Research Properties of pozzolan Behaviour of composite Particle Size Specific Surface Area Chemical Composition Mineralogy Amorphousness Water Demand Reactivity Compressive Strength Chemical Conductivity Setting Time Porosity

12 Methods - Physical characteristics pozzolans Particle Size laser diffraction - Malvern Mastersizer 2000 Particle Surface Area BET method - Quantachrome Nova 4200e Chemical Composition - % oxide - XRF Mineralogy and amorphousness - XRD Methods Behaviour / properties of pastes Lime: pozzolan pastes at 1:1 and 1:3 ratios and water content dependant on flow Water Demand Initial flow Setting Time VICAT test Reactivity Mechanical method : Compressive strength Chemical method : Conductivity in solution

13 Results Specific Surface Area and Particle Size Metastar, RHA, GGBS and PFA are the finest pozzolans (finer than lime). MS particles flocculated -finer than determined by laser. (60% of the MS particles are sized under 1 µm, therefore the finest). MS, Metastar and RHA - much greater specific surface area than any of the other pozzolans.

14 Results Water Demand It depends on: particle size; specific surface area; lime:pozzolan ratio surface area has the greatest influence on water demand Water Content (g) Ratio 1:1 Ratio 1: Surface Area (m2/g)

15 Results Water Demand finer pozzolans - greater water demand replacement of lime pozzolan reduced the water demand for all pozzolans except metastar 2 groups: High Water demand Meta, MS and RHA Low water demand Leca, PFA and brick dusts

16 Results Reactivity Both indices positioned the pozzolans in the same order of reactivity: Meta/GGBS/MS/RHA/Leca/PFA/YBD/Tile/RBD Mechanical Index Increasing silica content results in a higher mechanical index Dependant on the amount, type and microstructure of hydration products formed: S hydrates contributing more to strength than Al hydrates Pozzolanic Index (Mech) % Silica GGBS Leca Meta MS PFA RBD RHA Tile YBD

17 45 Activity Index (Mechanical) GGBS Leca Meta PFA RBD RHA Tile YBD D90 (um) strength increase as particle size decreases the filler effect

18 Reactivity and Strength Development 45 Pozzolanic Index (Mech) GGBS Leca Meta MS PFA RBD RHA Tile YBD increasing Amorphous Content a relationship between increasing amorphous content and reactivity clearly evident; amorphous materials - greater mobility and superficial location of their atoms

19 Mechanical index- Strength Development Metastar, GGBS, RHA and MS were found to be the most reactive pozzolans high specific surface area high amorphouness small particle size

20 Results Setting Time all pozzolans speed up the initial set of the lime paste except for PFA and MS all pozzolans reduced final setting time of the lime paste by at least 40% no clear relationship between reactivity and setting time a small increase in water content (5%) significantly slowed down the setting Depth of Penetration (mm) Time (hours) GGBS Leca Meta MS PFA RBD RHA Tile YBD Lime

21 Concrete made of lime and hemp Lime - Ca(OH) 2 Industrial Hemp Shiv woody inner core of stalk Cement often added to overcome the problems of extended setting times Proprietary mixes use pozzolanic additions and admixtures- water retainers

22 Use Developed in France during the early 1990s Historic evidence of organic material in lime Used in hundreds of buildings in France including the French Environment Ministry Approximately 20 buildings in Ireland

23 Adnams Brewery, Suffolk Photograph from AECOM Website

24 Environmental benefits Drop on CO 2 emissions 1- No emissions from hemp production 2- in order to grow - photosynthesis-, hemp sequestrates CO 2 from the atmosphere to produce cellulose: a carbon negative material.

25 Environmental benefits Further sequestration of atmospheric CO 2 - as it hardens the lime cycle A standard cavity wall is responsible for 100 Kg CO 2 emissions per m 2 of wall whereas, rather than emitting, a 500 mm hemp composite wall can lock up 53 Kg/m 2 of CO 2. CO 2 emissions Typical cavity walls +100 kg/m 2 300mm hemcrete wall - 31 kg/m 2 500mm hemcrete wall - 53 kg/m 2 This could save up to 30T in the walls of a typical house If used for the floor slab and roof insulation this can increase to 50T

26 Environmental benefits Drop on non- renewable natural materials consumption (rocks /fossil fuels used to produce cement Hemp is a renewable material, the 2 nd fastest growing plant on earth, growing from seed to 4 - to- be- Low embodied energy- can be locally produced. Can be fully recycled Low density- requires smaller foundations

27 Advantages and Disadvantages Environmentally sustainable Slow setting/drying times Good Thermal Performance Lack of technical knowledge High thermal insulation High thermal inertia Non load bearing Good vapour permeability- comfortable healthy interior High sound absorption Fire and pest resistant Ease of construction

28 The structural requirements are performed by the frame. Photos-Ian Pritchett- Lime Technology Ltd. Henry Thompson. The Old Builders Co.

29 BRE study at Haverhill Housing Project, Suffolk Photograph from Lime Hemp, Mainstreaming Bio Composite Construction by Patrick Daly in Construct Ireland

30 Thermal performance - Insulation HEMP AND LIME MORTAR CONSTRUCTION Cold exterior = low heat loss. CONVENTIONAL BLOCK CONSTRUCTION Warm exterior = high heat loss. U value thermal transmittance- measure of heat flow- inverse of R (thermal resistance)- rate of heat loss, Typical U- Values - density: U value of a 300 mm wall 0.30 ; 0.23 to 0.26W/m2.k commercial mix 400 mm wall 0.22 W/M 2 K 500 mm wall 0.18; 0.14 to 0.16W/m2.k H Thompson. THE OLDBUILDERS CO. I Pritchett. Lime tech ltd.

31 Thermal performance - tightness- monolithic building makes it inherently air tight- improves if sprayed Thermal bridging- The timber frames do not behave as thermal bridges Hygrothermal properties - High vapour permeability and absorption coefficient buffer high humidity / combat condensation improving air quality- improves thermal performance

32 Research Hydrated Lime and Commercial Binder Different hemp content for different applications (hemp: binder by volume) Wall 1:0.33 Floor 1:1 Plaster 1:9 Water Content Shrinkage, flexural and compressive strength

33 Shrinkage Shrinkage is unlikely to cause problems Organic fibres used to reduce shrinkage

34 greatest in the first 10 days: CL90-90% commercial mix 70-90% dependant on binder type, hemp content and water content binder type seems to have the strongest effect on shrinkage higher hemp content samples shrank more higher water content samples also shrank more

35 Flexural and Compressive Strength Low Strengths Gradual ductile No standards Compressive Strength 1.2MPa

36 Flexural Strength

37 Flexural Strength Behaviour

38 Compressive Strength

39 Compressive Strength Behaviour

40 Compressive Strength Behaviour