Where Im at now University of Bath Department of Architecture - - PowerPoint PPT Presentation

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Where Im at now University of Bath Department of Architecture - - PowerPoint PPT Presentation

Jan 09, 2024 589 likes •1.04k views

Where Im at now University of Bath Department of Architecture & Civil Engineering (ACE) BRE Centre for Innovative Construction Materials EPSRC CDT in Decarbonisation of the Built Environment 2017-10-11 'Building out of

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Where I’m at now

  • University of Bath
  • Department of

Architecture & Civil Engineering (ACE)

  • BRE Centre for

Innovative Construction Materials

  • EPSRC CDT in

Decarbonisation of the Built Environment

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My team

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Dept of Architecture & Civil Engineering, University of Bath Prof Andrew Heath Dr Mark Evernden Prof Pete Walker Prof Venkatarama Reddy, Indian Institute of Science Dr Pascaline Patureau, Dept of Chemistry, University of Bath

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My backstory

  • Materials Science

MEng (2009-13)

  • Graduate

Sustainability & Physics Engineer (2013-15)

  • University of Bath,

PhD (2015-18)

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My backstory

  • Construction training

charity

  • Interlocking

stabilised soil blocks (ISSB)

  • Replacement for

cement?

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Part I – the problems

  • f housing

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Draw your dream home!

  • Location?
  • Materials?
  • Type of home?
  • View?
  • Colour scheme?

2 minutes…

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Demographic context of housing

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2014 population growth rates, World Bank

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Demographic context of housing

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UNDESA, 2015. World Population Prospects: The 2015 Revision, Key Findings and Advance Tables. Working Paper No. ESA/P/WP.241.

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Demographic context of housing

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UN-HABITAT, 2014. World Habitat Day: Background Paper. Nairobi. UNDESA, 2014. World Urbanization Prospects: The 2014 Revision, Highlights (ST/ESA/SER.A/352). UNDESA, 2015. World Population Prospects: The 2015 Revision, Key Findings and Advance Tables. Working Paper No. ESA/P/WP.241.

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Informal construction sector

  • 1. Self-building
  • 2. Stockpiling
  • 3. Materials spectrum
  • 4. Insecurity of tenure

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By Claudio Allia (Own work) [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons

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Informal settlement or slum?

  • Informal settlement =

HOW it’s built

  • Slum = WHAT this

settlement is i.e. inadequate,

  • vercrowded

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By Claudio Allia (Own work) [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons www.sdinet.org

Slum Dwellers International (SDI) www.sdinet.org

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Current walling materials used

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UN-HABITAT, 2009. INTERLOCKING STABILISED SOIL BLOCKS: Appropriate earth technologies in Uganda. Nairobi: UN-HABITAT.

  • More durable
  • Higher social

status

  • More expensive
  • Higher impact
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Informal construction

Pros? Cons?

  • Structural quality
  • Internal environment
  • Construction safety
  • Expensive transport
  • Waste
  • Lack of materials

innovation

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  • Very cheap
  • Flexible
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Respecting existing…

Attitudes Processes

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Rwanda Cricket Ground design, Light Earth Designs LLP

Marsh, A. et al., 2016. A Holistic Materials Design Requirements Framework (HoMDReF) For Future Housing Materials. Integrated Design at 50: Building our Future.

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Broad research question

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It’s got to be…

  • Affordable
  • Practical
  • Sustainable
  • Aspirational

Put another option on the table The best of earth and the best of concrete?

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Puzzle #1!

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Part II – geopolymers and stabilised soil materials

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What is soil?

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= “uncemented or weakly cemented accumulation of mineral particles formed by the weathering of rocks as part of the rock cycle, the void space between the particles containing water and/or air.” = clay + other minerals

Knappett, J. (2012). Craig's soil mechanics. Abingdon, Abingdon : Spon. Reeves, G. M., et al. (2006). Clay materials used in construction. London, London : Geological Society.

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What are clay minerals?

  • Alumino-silicates

= mostly aluminium, silicon, oxygen and hydrogen (plus some minor others)

  • Sheet structure

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Knappett, J. (2012). Craig's soil mechanics. Abingdon, Abingdon : Spon. Reeves, G. M., et al. (2006). Clay materials used in construction. London, London : Geological Society.

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Unstabilised soil materials

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Shibam, Yemen By Goldzahn [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons Hope Cove, Devon By Nilfanion (Own work) [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons

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Stabilised soil materials

How to stabilise?

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  • Mechanical
  • Compaction
  • Grading
  • Chemical
  • Cement
  • Lime
  • Other…?
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Stabilised soil materials

Why stabilise soil to build with?

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  • Maintenance
  • Termites
  • Lifestyle
  • Aesthetics

Images courtesy of Haileybury Youth Trust

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Geopolymers

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Davidovits, J., 2011. Geopolymer chemistry and applications. 3rd ed. ed. Saint-Quentin: Saint-Quentin : Institut Geopolymere.

= amorphous, synthetic, alkali aluminosilicates

  • 2

2

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Geopolymer formation reaction

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  • Four stages
  • Disassembly, then

reassembly

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Why are we interested?

Pros

  • Low temperature

reaction  low embodied energy

  • Starting materials - can

use abundant or waste materials

  • Properties
  • Strength
  • Durability
  • Fire resistance
  • Acid resistance

Cons

  • High pH solutions

required

  • Reaction still not fully

understood

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Geopolymer stabilised soil materials (GSSM)

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= use geopolymer phase to stabilise soil = geopolymer reaction transforms clay in soil into a geopolymer

Could GSSM be…

  • Affordable?
  • Practical?
  • Aspirational?
  • Sustainable?
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Why are we interested?

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Hischier, R., et al. (2010). Implementation of life cycle impact assessment methods. Ecoinvent Report. Hammond, G. and Jones, C. (2011). Inventory of carbon & energy (ICE). Sustainable Energy Research Team (SERT). Version, 1. Hashemi, A., Cruickshank, H. & Cheshmehzangi, A., 2015. Environmental Impacts and Embodied Energy of Construction Methods and Materials in Low-Income Tropical Housing. Sustainability, 7(6), p. 7866. Maskell, D., 2013. Development of Stabilised Extruded Earth Masonry Units.

Footprint of GSSM

  • NaOH
  • “Firing”
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Problems with GSSM

Unknowns

  • How much activating

NaOH do we need?

  • Which soils does this

reaction work on?

  • How to make the
  • ptimal ‘recipe’ for a

given soil?

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My research

Comparison of pure clay minerals’ behaviour Predict behaviour of real soil

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Is this technology feasible for all soil types? Or just a small fraction?

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Manufacture

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Manufacture

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Methods

  • Which phases are

present?

  • How much of each

phase is present?

  • How are they

distributed?

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1x10-1m 1x10-2m 1x10-3m 1x10-4m 1x10-5m 1x10-6m 1x10-7m 1x10-8m 1x10-9m 1x10-10m

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Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR)

  • Uses magnetic pulses
  • Information about

atomic bonding coordination

  • Shows change from

sheet to network coordination on reaction

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1x10-1m 1x10-2m 1x10-3m 1x10-4m 1x10-5m 1x10-6m 1x10-7m 1x10-8m 1x10-9m 1x10-10m

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Powder X-ray diffraction (XRD)

  • Uses single

wavelength X-ray radiation

  • Identifies crystalline

phases present

  • More difficult for

geopolymers, as these are non-crystalline.

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1x10-1m 1x10-2m 1x10-3m 1x10-4m 1x10-5m 1x10-6m 1x10-7m 1x10-8m 1x10-9m 1x10-10m

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Scanning electron microscopy (SEM)

  • Like a light

microscope - but with electrons.

  • Shows microstructure

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1x10-1m 1x10-2m 1x10-3m 1x10-4m 1x10-5m 1x10-6m 1x10-7m 1x10-8m 1x10-9m 1x10-10m

Clay Geopolymer- stabilised clay

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Strength and durability tests

Simple but useful!

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1x10-1m 1x10-2m 1x10-3m 1x10-4m 1x10-5m 1x10-6m 1x10-7m 1x10-8m 1x10-9m 1x10-10m

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What I’ve learnt so far

  • Not just about

chemical composition – clay mineralogy very influential

  • Sensitive reaction –

no simple recipes

  • Possibly NOT

suitable for localised production?

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Puzzle #2!

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Part III – questions and conundrums

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  • 1. Research…
  • r development?

Research Product development Long term Short term Specific application Broad application

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  • 2. How to choose a

research topic?

  • Skills, interests and

priority of topic.

  • What makes an issue

a priority problem?

  • Scale
  • Neglectedness
  • Solvability
  • What are the priority

problems in engineering?

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https://80000hours.org/career-guide/most-pressing-problems/ https://80000hours.org/articles/cause-selection/

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Thanks for listening! Any questions?

  • Geopolymers?
  • Soil materials?
  • Research v product

development?

  • Priority problems in

materials and engineering?

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Email: a.marsh@bath.ac.uk Twitter: @AlastairMarsh