3D printing concrete:

Fresh Properties and

RheologyM. Sonebi, Queen’s University Belfast, UK

M. Rubio, Queen’s University Belfast, UK

S. Amziane, Polytech-Clermont Ferrand, France

A. Perrot, UBS Lorient, France

Increase of population, need more houses,

infrastructures, etc

World population on Sept 26, 2017 at 19:25 pm GMT 7,570,100,000

World population on Sept 26, 2017 at 19:30 pm GMT7,570,101,000

(+1000)

Conservative estimation of the amount of concrete

produced every year on the planet:

more 15,000,000,000 t

…over 2 ton/inhabitants; and there are good

reasons for this …. is cost (cheaper!)

Conventional Construction of buildings

Labour intensive and inefficient, time of construction, health and

safety insurance, society, ..

Wasteful and Climate Change : emission of CO2 (carbon foot print)

Modern slaves in some countries, Corruption prone (tender, during

construction, market, etc),

High cost

Solutions

• We used robotics now to produce our cars, appliances, mobiles, TV, computers, iphone,

Ipad, iwatch, clothes, shoes, foods, mails, etc

Digital – future with robots buildings

Race to build first 3D-printing building

The race to build the first 3D-printed building is already started.

Would you live in a house that came out of a printer? Would you prefer Concrete, or

Plastic? Biodegradable, or Weather resistant? Canal house or futuristic spider's nest?

The phrase "form follows function" was coined in 1896, just as it became clear that

concrete, glass and steel would free architects to design buildings in completely new ways

that had nothing to do with what came before. What's going to happen to the buildings we

erect with 3D printers?

A future with robots

It seems every week we hear a new doom-

laden prediction about the impact of robots

and other forms of automation on jobs. But

are we looking at this the wrong way - too

inclined to hang on to the world of work as it

is today, too unimaginative about how it

could be transformed for the better by

technology?

The robots, like other tools invented by

humans, can help us or harm us.

But they are not going away.Not all robots would be good to live with

Benefits of 3 D printings

We can enumerate the benefits of 3D printing in construction: “It is always worth reiterating, the main benefits of concrete-3D printing on a large scale are as follows:

1. Higher customisation potential (flexibility in design, and environmental impact)

2. Very low construction waste (Formwork represents 35-60% of the overall cost)

3. Reduced need of more labour (Health and safety)

4. Reduced time of the construction (Cost-effective)

University Loughborough (UK)

(Le et al. 2012)

(Free Construction Research Project – 2010)

First 3D bench

On 16 Feb - 2017

Objectives

The aim of this study is to characterize the effect of the fly

ash, silica fume, the dosage of SP, dosage of fibres, and the

type of viscosity modifying admixtures on the workability, the

rheological behavior and opening time of 3D printing mortar.

Experimental program

Parameter Values

W/CM 0.50

Fly ash 24%

Silica fume 8%

SP (0.55%, 0.28%)

SP – ½ SP

Polypropylene Fibres (6mm) (1.2kg/m3); PP-2PP-3PP

VMAs – Diutan gum(DG) & Nano-clay(nC) (by mass of

CM)

0.05% - 0.10%

Materials

Ordinary Portland cement : Class 42.5 N (BS ENV 197-1 CEMI)

Fly ash – BS EN 450

Silica fume (BS EN 13263-1)

Sand (1.18 mm)

SP - polycarboxylic ether (30% SC, 1.05)

VMAs - diutan gum (Polysaccharide gum), Nano-clay

Polypropylene fibres

Experimental Program

11

Tests

Fresh tests methods

1) Flow table test

Consistency

2) Penetrometer test

Consistency

3) Cylindrical slump flow

Semi-empirical yield stress

Mixes were too stiff to be characterised

by the viscometer

4) Gun test

Extrudability

5) Time gap test

Build up rate of cement based

material

Limit of stiffness for extrusion

Measurements every 15 min

1

2

3

4

Effect of fly ash on fresh properties of 3D printing

NO FA

FA35

36

37

38

39

40

230

240

250

260

270

280

290

NO FA SP PP SP PP

Pen

etr

om

ete

r (m

m)

Slu

mp

flo

w (m

m)

Slump f low Penetrometer

With FA

Effect of Silica fume on fresh properties of 3D printing

NO SF

SF20

25

30

35

40

0

50

100

150

200

250

300

SP PP SF SP PP

SP 2 PP

SF SP 2PP

Pe

ne

tro

mete

r (m

m)

Slu

mp

flo

w

(mm

)

Slump flow Penetrometer

S.FlowS.Flow

Pntr Pntr

Effect of SF on fresh properties of 3D printing

NO SF

SF0

200

400

600

800

1000

0

50

100

150

200

250

300

SP PP SF SP PP

SP 2 PP

SF SP 2PP

Es

tim

ate

d y

ield

str

es

s (

Pa

)

Slu

mp

flo

w

(mm

)

Slump flow Estimated yield stress

Est. z

Effect of PP fibre on fresh properties of 3D printing

10

20

30

40

50

210

220

230

240

250

260

SP PP SP 2 PP SP 3PP

Pe

ne

tro

mete

r (m

m)

Slu

mp

flo

w (m

m)

Slump flow Penetrometer

S.Flow

Pntr

PP

2PP

3PP

1PP

2PP

3PP

Effect of reduction of SP on fresh properties of 3D printing

15

20

25

30

35

40

0

50

100

150

200

250

300

SP PP 1/2SP PP SP 2 PP 1/2SP 2PP SP 3PP 1/2 SP 3 PP

Pe

ne

tro

me

ter

(mm

)

Slu

mp

flo

w (

mm

)

Slump flow Penetrometer

SP

PP 2PP 3PP

Effect of reduction of SP on fresh properties of 3D printing

0

200

400

600

800

1000

1200

0

50

100

150

200

250

300

SP PP 1/2SP PP SP 2 PP 1/2SP 2PP SP 3PP 1/2 SP 3 PP

Es

tma

ted

yie

ld s

tre

ss

(P

a)

Slu

mp

flo

w (

mm

)

Slump flow Estimated yield stress

PP 2PP 3PP

τ

τ

Effect of type of VMA on fresh properties of 3D printing

10

20

30

40

50

0

50

100

150

200

250

300

SP PP VMA1 SP PP

VMA2 SP PP

Pe

ne

tro

me

ter

(mm

)

Slu

mp

flo

w (

mm

)

Slump flow Penetrometer

VMA1-DG VMA2-nC

0

200

400

600

800

1000

0

50

100

150

200

250

300

SP PP VMA1 SP PP

VMA2 SP PP

Es

tim

ate

d y

ield

str

es

s (

Pa

)

Slu

mp

flo

w (

mm

)

Slump flow Estimated yield stress

Effect of type of VMA on fresh properties of 3D printing

VMA1-DG VMA2-nC

Correlation between slump flow vs.

penetration of 3D printing

R² = 0.86

100

120

140

160

180

200

220

240

260

280

17 22 27 32 37 42

Slu

mp

Flo

w (

mm

)

Penetration (mm)

R² = 0.89

140

150

160

170

180

190

200

19 24 29 34

Slu

mp

Flo

w (

mm

)

Penetration (mm)

(a) different PP and SP (b) with and without SF

Correlation between yield stress flow vs.

penetration of 3D printing

(a) different PP and SP (b) with and without SF

R² = 0.88

100

120

140

160

180

200

220

240

260

15 215 415 615 815 1015 1215

Slu

mp

Flo

w (

mm

)

Yield stress (Pa)

R² = 0.81

100

110

120

130

140

150

160

170

180

190

200

600 700 800 900 1000 1100

Slum

p Fl

ow

(mm

)

Yield stress (Pa)

Opening time – Effect of FA & SF on 3D printing

(a) FA (b) SF

Opening time – Effect of PP fibre & SP on 3D

printing

(a) PP fibre (b) SP

Opening time – Effect of type of VMA on 3D printing

DG

nC

Printability

0

200

400

600

800

1000

1200

1400

0 20 40 60 80 100 120 140 160

Es

tim

ate

d y

ield

str

ess

(P

a)

Time (min)

risk of none printability

Mix too fluid and risk of drainage

risk of none printability

surface defect, risk of drainage and

reduce of the rate due to the

stiffness of the mix

"Printable" mixes

Cold joints

If layers of concrete have

limited intermixing and if the

critical resting time value has

been exceeded, cold joints are

susceptible to appear.

Coloured layers-intermixing

3 D printing layers

2 printed layers 4 printed layers

13 mm

13 mm

11 mm

10 mm

13 mm

13 mm

Recommendations of 3D printing mortar

155 mm < spread diameter < 235 mm

open time <100 min

600 < τ0 <1050 Pa

20 < Penetration < 39 mm

3D polar bear at Copenhagen Airport – Aug. 2016

Visual illusion

(3D vs. 2D)

Thank you for your attention