potentials of polysaccharides to control the rheology of
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www.bam.de
POTENTIALS OF POLYSACCHARIDES TO
CONTROL THE RHEOLOGY OF CONCRETE
Wolfram Schmidt
10.03.2021
Congratulations – 30 years of Conference
Series “Rheology of Building Materials”
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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Thank you for 30 years of
– Interesting talks
– Exciting discussions
– Hosting the “rheology family”
https://www.150.bam.de
Photo: Schleibinger Photo: Schleibinger
Photo: Schleibinger Photo: Schleibinger
Polysaccharides
Role of polysaccharides in rheology
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
3
2011
2017
2015
Past presentations on polysaccharides on this conference by the presenter:
- Influences of modification (2011)
- Casting robustness (2015)
- Sustainability(2017)
Polysaccharides
Role of polysaccharides in rheology
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
4
https://tu-dresden.de/bu/bauingenieurwesen/ifb/forschung/spp2005
Past presentations on polysaccharides on this conference by the presenter:
- Influences of modification (2011)
- Casting robustness (2015)
- Sustainability(2017)
- Future casting technologies will require new admixture groups that can tailor the rheology at every process step.
Polysaccharides
Role of polysaccharides in rheology
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
5
Superplasticizers can disperse particles and thus reduce the yield stress.
This alone cannot sufficiently create the rheological specifications required for more industrialised processing.
Polysaccharides can become an important group of novel agents in concrete technology.
Polysaccharides
What are polysaccharides?
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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– Polysaccharides are macromolecules consisting of monosaccharides (sugar)
– The most important ones occurring in nature are cellulose and starch, which consist of glucose only.
Starch
Cellulose
Polysaccharides
What are polysaccharides?
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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– Polysaccharides are macromolecules consisting of monosaccharides (sugar)
– The most important ones occurring in nature are cellulose and starch, which consist of glucose only.
– Often polysaccharides are branched.
Starch
Amylose (linear, small)
Amylopectin (branched, huge)
Polysaccharides
What are polysaccharides?
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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– Polysaccharides are macromolecules consisting of monosaccharides (sugar)
– The most important ones occurring in nature are cellulose and starch, which consist of glucose only.
– Often polysaccharides are branched.
– More complex polysaccharides used in construction are e.g. diutan gum and guar gum
Starch
Diutan gum
Glucose Glucuronate Glucose Rhamnose
Rhamnose Rhamnose
www.bam.de
Starch
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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Starch
Effect in liquid phase
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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Starch
Diutan gum
Starch
Peculiarity of starch
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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No particles In presence of particles In presence of PCE
Starch
Yield stress and particle interactions
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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– With increasing particle volume fraction, the effect of starch becomes stronger.
– At very low w/p it is stronger than diutan gum.
Starch
Influencing factors
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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– Application (liquid/solid)
– Ratio of amylose and amylopectin
– Size and/or Mw of amylopectin
– Mode of modification
– Degree of substitution
– Presence of other polymers, e.g. PCE
– Adsorption
– Time / cement hydration
Starch
Role of polysaccharides in rheology
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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0
20
40
60
80
100
120
140
160
180
0.00% 0.25% 0.50% 0.75% 1.00% 1.25% 1.50%
Dre
hm
omen
t [N
mm
]
Polymergehalt [M.-% des Pulvers]
Kartoffelstärke
Cassavastärke
-10
10
30
50
70
90
110
130
150
0 40 80 120 160 200 240
Dre
hm
omen
t [N
mm
]
Umdrehungsgeschwindigkeit [Upm]
Referenz
Kartoffel-
stärke
Cassava-
stärke
Cassava starch
Potato starch Potato
starch
Cassava
starch
Reference
Polymer content [% by weight of of powder] Rotational speed [rpm]
Torq
ue [
Nm
m]
Torq
ue [
Nm
m]
Starch
Role of polysaccharides in rheology
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
15
Cassava starch
→ Negative zeta potential with Ca2+
→ Rhyd ~ 100 nm
Cassava Potato
Starch
Role of polysaccharides in rheology
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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https://youtu.be/4H-0R75Zyv0?list=PLKqa3Uo_GQNs0mogyrcCYusuYtbJWOcT3
Starch
Role of polysaccharides in rheology
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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https://youtu.be/4H-0R75Zyv0?list=PLKqa3Uo_GQNs0mogyrcCYusuYtbJWOcT3
Potentials:• inexhaustible global availability• great variability• low cost
www.bam.de
Acacia gum
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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Acacia gum
Typical uses and properties
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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– Easily water soluble gum
– Grows in the tropical and subtropical regions of Africa, India, and the Americas
– Typical use in food industry and cosmetics
– ¾ of the global consumption is produced in Sudan
Acacia gum
Effect in cementitious materials
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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0
10
20
30
40
50
60
70
80
90
100
0.00% 0.05% 0.10% 0.15% 0.20%
Dre
hm
omen
t [N
mm
]
Polymergehalt [M.-% des Pulvers]
PCE (Fertigteil)
PCE (Transportbeton)
Akaziengummi (Sudan)
Akaziengummi (Südafrika)
Ligninsulfonat
PCE (pre-cast)
PCE (ready mixed)
Acacia gum (Sudan)
Acacia gum (South Africa)
Lignosulfonate
Polymer content [% by mass of powder]
Torq
ue [
Nm
m]
Stabilising effectPlasticizing effect
Acacia gum
Performance specifications
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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w/c = 0.3
0.35% GA
w/c = 0.4
0.35% GA
Workability depends on:
– Dosage of gum
– Mixing intensity
– Mixing duration
– Particle volume fraction
– No plasticizing effect at very low w/c
– Plasticizing effect at moderate w/c
Acacia gum
Performance specifications
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
22
Acacia gum
→ Negative zeta potential
→ With Ca2+ wide range of Rhyd ~ 10nm-2µmPotentials:• not yet commercialised in many regions in the world• occurs in regions with restricted access to admixtures• no complex processing required
www.bam.de
Triumfetta pendrata A. Rich
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
23
Triumfetta pendrata A. Rich
What is it?
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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Par Tatoute — Travail personnel, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=19808793
0.08% Nkui
Triumfetta pendrata A. Rich
Thixotropy
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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Similar flowability
after 15 x lifting and
dropping
Significant flow
reduction only under
gravity load
Triumfetta pendrata A. Rich
Thixotropy
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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20
40
60
80
100
120
140
0
10
20
30
40
50
60
70
80
0 5 10 15 20 25 30 35 40 45 50 55 60 65
Time [min]
Sh
ear
stre
ss [
Pa]
Sh
ear
rate
[1/
s]
Triumfetta pendrata A. Rich
Thixotropy
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
27
Triumfetta pendrata A. Rich
→ Negative zeta potential
→ With Ca2+ agglomerates up to 5 µmPotentials:• Rapid structural build-up without need to accelerate
the cement hydration
www.bam.de
Summary and outlook
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
28
Summary and outlook
Biopolymers vs. synthetic polymers
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
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Polysaccharides have enormous potentials as rheology modifiers
• Starch
• Acacia gum
• Bark gum of Triumfetta
The approach is different from synthetic polymers, which can be tailored to the application:
1. first understanding of basic mode of operations
2. Identify ideal use
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
30
Summary and outlook
New sources need to be identified
RefAnimal based
Bio-wastebased
Plant based
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
31
Summary and outlook
Sustainability potentials
http://globe.rilem.net
GLOBE Global Consensus on Sustainabilityin the Built Environment
Circularity – environment - socio-economic equity
www.bam.de
Thank you for your attention.
Contact:
Wolfram Schmidt
FB 7.4
Email: wolfram.schmidt@bam.de
10.03.2021Rheology of Building Materials | Online Colloquium | 30 Years | virtual Regensburg Potentials of polysaccharides to control the rheology of concrete | wolfram.schmidt@bam.de | BAM
32
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