RHEOLOGY MODIFYING ADMIXTURES FOR CONCRETE TAKEN FROM NATURE Wolfram Schmidt 1 , Inès L. Tchetgnia Ngassam 2 , Rose Mbugua 3 , Kolawole A. Olonade 4 1 BAM Bundesanstalt für Materialforschung und –prüfung 2 University of Cape Town 3 Tshwane University of Technology 4 Obafemi Awolowo University 21.02.2017
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RHEOLOGY MODIFYING ADMIXTURES
FOR CONCRETE
TAKEN FROM NATURE
Wolfram Schmidt1, Inès L. Tchetgnia Ngassam2,
Rose Mbugua3, Kolawole A. Olonade4
1 BAM Bundesanstalt für Materialforschung und –prüfung2 University of Cape Town3 Tshwane University of Technology4 Obafemi Awolowo University
21.02.2017
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Co-authors
2
Rose Mbugua
Tshwane University of
Technology, ZA
Inès Tchetgnia Ngassam
University of
Cape Town, ZA
Kolawole A. Olonade
Obafemi Awolowo
University, NG
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Introduction
3
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
‒ Strength evolution
Introduction
Relevance of rheology modifying admixtures
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Self-levelling
Flowable
Soft
Plastic
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UHPC
HPC
Normalstrength
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Pa]
Spre
ad fl
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Self-levelling
Flowable
Soft
Plastic
Stiff
UHPC
HPC
Normalstrength
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mp
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[M
Pa]
Spre
ad fl
ow
dia
me
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[mm
]
Self-levelling
Flowable
Soft
Plastic
Stiff
UHPC
HPC
Normalstrength
Lignosulfonates
Naphthalene sulfonates
Melamin sulfonates
Polycarboxylates
Vinyl copolymers
4
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
‒ Strength evolution
‒ New casting technologies
Introduction
Relevance of rheology modifying admixtures
5
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
‒ Strength evolution
‒ New casting technologies
‒ New architecture
Introduction
Relevance of rheology modifying admixtures
phænoby Zaha Hadid, Source: Wikipedia
www.bewegteflaeche.de
6
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
‒ Strength evolution
‒ New casting technologies
‒ New architecture
‒ Special applications
Introduction
Relevance of rheology modifying admixtures
Source: BAM
7
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
‒ Strength evolution
‒ New casting technologies
‒ New architecture
‒ Special applications
‒ Sustainability and environmental
friendliness
Introduction
Relevance of rheology modifying admixtures
Source: BAM
8
WWF, 2008
Barcelo et al., 2014
Rheology modifyingadmixtures are the key to
sustainable, and innovative construction.
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Relevance of rheology modifying
admixtures in Africa
9
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Relevance for Africa
Economy and society
10
• Africa‘s economies grow at rapid pace.
• Investment in construction ensuresongoing growth and triggers newdevelopments.
• The most crucial challenges are:
• Infrastructure
• Housing
• Construction business allows thepopulation to participate in economicgrowth, and thus ensures social stability.
• Admixtures support efficient andsustainable construction.
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Relevance for Africa
Affordable construction
11
• Cement is extremely expensive.
• Alternatives do exist, e.g.:
• Rice husk ashes
• Cassava peel ashes
• Bagasse ashes
• But pozzolanic materials typicallyrequire admixtures to compensate forthe higher water demand.
Msinjili, 2015 Olonade, 2015 Wikipedia
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Relevance for Africa
Sustainability
12
• Admixtures help to minimise the cementcontent as well as the w/c.
• Therefore today, the correlation between high cement content and good concrete does not hold true anymore.
Aitcin, 2000
Morgan Stanley Research, 2015
CEMNET, 2013
Admixtures
required to avoid
the hump
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Relevance for Africa
Global effects
13
• Hence, admixtures are of enormousrelevance for the African continent.
• However, they are also extremelyimportant for the global environment, since reasonable concrete technology will achieve the greatest momentum today in Africa.
• Sustainable concrete technology pays back a multiple due to the rapid cement marketgrowth, to the benefit of:
• The environment
• Local markets
• Global markets
International EnergyAgency
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Relevance for Africa
Admixture shipments to Africa
14
• Admixture supply from outside, and mainly coastal regions.
www.maps.google.de
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Relevance for Africa
Admixture shipments to Africa
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• Admixture supply from outside, and mainly coastal regions.
• Alternatives are required.
• Africas strength is agriculture.
• 600 Million ha of unused agriculturalareas (Perry 2016).
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Relevance for Africa
Admixture shipments to Africa
16
• Admixture supply from outside, and mainly coastal regions.
• Alternatives are required.
• Africas strength is agriculture.
• 600 Million ha of unused agriculturalareas (Perry 2016).
• Local plants and local agriculturalwastes can be used, like
• Acacia gum
• Lignosulfonate
• Starch
• Nkui
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
17
Cement, 20 µm
PCE
GAK, LS
Amylopectin
NkuiEttringite
Cement, 5 µm
Relevance for Africa
Comparison
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Acacia gum as superplasticizer
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21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Acacia gum
Origin
19
• Acacia gum can be obtained from the stem, e.g. from Acacia Karoo Hynes
• One tree can be harvested for 15 years
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Acacia gum
Influence on rheology
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• An increasing dosage of GAK (Acacia gum from the Karoo) can significantly enhance the slump of concrete.
• Set retardation could be observed, but it was not dramatic and caneven be positive high temperature conditions.
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Acacia gum
Influence on rheology
21
• An increasing dosage of GAK (Acacia gum from the Karoo) can significantly enhance the slump of concrete.
• Set retardation could be observed, but it was not dramatic and caneven be positive high temperature conditions.
• In future research the use ofGAK as admixture for SCC in East Africais observed in cooperation betweenTshwane University of Technology, the Pan-African University at Kenyatta University and BAM.
see MSc thesisCaroline Mwende
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Acacia gum
Influence of solid volume fraction on GA
w/c = 0.3
0.35% GA
w/c = 0.4
0.35% GA
w/c = 0.3
0.35% PCE
w/c = 0.4
0.35% PCE
w/c = 0.3
w/c = 0.4
22
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Lignosulfonate
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21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]
Lignosulfonate
Peculiarities of lignosulfonate
24
Lignosulphonates are typicallyconsidered as plasticizer.
• Waste product of cellulose industry
• More water required than with PCE
• More complex adjustment.
Lignosulfonates pointed out toperform very well in conjunction withporous surfaces such as rice huskashes.
• For further information, please seeNsesheye Susan Msinjili
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Dosage of superplasticizer [% of cement]
PCE; w/b=0.31
LS; w/b=0.31
LS; w/b=0.6
21.02.2017Rheology modifying admixtures for concrete taken from nature | 26. Kolloquium | Rheologische Messungen an mineralischen Baustoffen | OTH Regensburg | [email protected]