digital concrete: opportunities and challenges...physical chemistry of building materials eth zurich...

Physical Chemistry of Building MaterialsETH Zurich

Robert J. Flatt, Institute for Building Materials, ETH Zurich

Digital concrete: Opportunities and challenges

2Physical Chemistry of Building MaterialsETH Zurich

Digital Concrete: Opportunities and Challenges


National Centre of Competence in Research: Digital Fabrication in Architecture

Interdisciplinary initiative to foster the innovation capacity of architecture and constructionLaunch: June 2014

Duration: 3 x 4 year phases = 12 years

Composition: 13 Professors, (+3 associated) 8 Postdocs 24 PhD researchers (+17 associated) MAS teaching program Industry collaboration programme

Robotic Fabrication Lab, Institute for Technology in Architecture, ETH Zurich


Profs. M. Kohler and F. Gramazio(ETH Zürich)


Digital Concrete: Opportunities and Challenges

The Economist, April 2012 The Economist, April 2014


Concrete 29 % Formwork

53 %

Steel 18 %

Source: E. Lloret

Smart Dynamic Casting


RetardedSelf Compacting Mortar

Robot and Formwork

Offline measurement

Process setup Chemical AdmixturesAccelerator

Control system


RetardedSelf Compacting Mortar

Automation: activation and feeding

Robot and Formwork

Inline measurement

ControlSynchronise: acceleration, filling, slipping, shaping.

Process setup Chemical AdmixturesAccelerator


Fabrication

Includes standardReinforcement !


Digital ConcreteProcessing

Mesh Mould Smart Dynamic Casting

ContourCrafting

3D Printing(Moulds/direct)

13

Digital concrete processing: Rheology and Hydration control

Rheology control Rheology & Hydrationcontrol


Layered based printingConcrete / mortar / paste extrusion

14


15

Physical Chemistry of Building MaterialsETH Zurich 16


Basic consideration on layered extrusion

h

𝜏"," = 𝜌𝑔 ℎ 3�⁄

Roussel and Coussot (2005), Shahab et al, (2013), Perrot et al (2015)



𝐴 > 𝜏","/𝑡/

h

𝑉 < 3� 𝐿 𝐴 𝜌𝑔ℎ⁄𝑡/ = 𝐿 𝑉⁄𝜏"," = 𝜌𝑔 ℎ 3�⁄

Roussel and Coussot (2005), Shahab et al, (2013), Perrot et al (2015)



h

𝑉 >𝜌𝑔ℎ4

4𝜇7𝑡89:; <𝜌𝑔ℎ 4

12 + 2𝜇7𝑉ℎ

4�

𝐴Roussel and Cussigh, CCR, 2008


Operating windowThere is an upper and a lower bound for the production rate• Too low rates give cold joints• Too high rates collapse under their own weight

Important factors are• Thixotropic build up• Contour length• Layer height• Linear rate

Contour length is a crucial factor when discussing whether or not cold joints form


What about reinforcement?Do not bother us with that question …Traditional• Place after and infill• Consider printed material as a lost formwork• Limited (probably insufficient) amounts of steel

Fiber reinforcement• Limited interconnection between layers• Gets worse at high speeds that avoid cold joints

Mats• Place ad hoc during production• Efficiency ???


Mesh Mould:Robotically produced Meshes as formwork AND reinforcement

Formwork + Reinforcement Formwork = Reinforcement


Mesh Mould: Key advance and resulting material challenge

Steel à Adequate quantity for ductile behaviord

D Rate limiting step: weld points

Increase d à decrease weld points àincrease D

Special mix design needed:Self compacting concrete that stays in the mesh

timesavingfactor ∝𝑑4𝑑N

O

Gramazio Kohler Research ETH Zurich


What about the environment?


Enrico DiniD-Shape

3D Printing – Powder beds 26


27

28Physical Chemistry of Building MaterialsETH ZurichDigital Building TechnologiesETH Zurich28 Imprimer le Monde, Centre

Pompidou, 2017


Imprimer le Monde, Centre Pompidou, 2017Digital Building Technologies

ETH Zurich29

Digital Grotesque II

Imprimer le Monde, Centre Pompidou, 2017


dfab house: EMPA NEST

30


NEST – dfab house •Robotically fabricated timber units

•Smart Slab (3D Printed)

• SDC facade mullions

•Mesh Mould wall

•Unit backbone

•Base


1st RILEM International Conference on Concrete and Digital Fabrication

http://digitalconcrete2018.ethz.ch/

Extended abstractDeadline:

15 October 2017


RobIArch 2018Robotic Fabrication in Architecture, Art, and Design

10th–15th SEPTEMBER 2018, ETH ZURICH


ConclusionsExciting new field with a lot of challenges and opportunities

Value will come when added functionality can be delivered

Tue interdisciplinarity is crucial• Architecture, civil engineering, robotics, materials science,

chemistry and processing

New area for material science and chemistry of concrete

Science and technology of concrete admixtures are esential !


Acknowledgements

Digital ConcreteProcessing

Mesh Mould

3D Printing Extrusion

Smart Dynamic Casting


image is by AndrewRae.org.uk

Thank you for your attention

digital concrete: opportunities and challenges...physical chemistry of building materials eth zurich...

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