Effets des superplastifiants de types polycarboxylates et de l’acide citrique sur l’hydratation et la rhéologie des ciments sulfoalumineux-bélitique

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Effets des superplastifiants de types polycarboxylates et de l’acide citrique sur l’hydratation et la rhéologie des

ciments sulfoalumineux-bélitique Rachid Belhadi, Alexandre Govin, Philippe Grosseau

To cite this version:

Rachid Belhadi, Alexandre Govin, Philippe Grosseau. Effets des superplastifiants de types polycar-boxylates et de l’acide citrique sur l’hydratation et la rhéologie des ciments sulfoalumineux-bélitique. Journée Scientifique 2018 du Codegepra, Nov 2018, Saint-Etienne, France. Journée scientifique du CODEGEPRA - Le Génie des Procédés en Rhône-Alpes Auvergne, pp.25 / P15. �hal-01991878�

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 0 2 4 6 8 10 12 A d s o rp ti o n (m g p o ly m e r / g c e m e n t) Polymer concentration in IS (g.L-1) PCE1 PCE2 PCE3 Langmuir 0 20 40 60 80 100 120 140 160 180 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 In iti al setti n g ti m e (m in ) Dosage of admixture (wt%) PCE1 PCE2 PCE3 CA 0.2CA+0.2PCE1 0.2CA+0.2PCE2 0 50 100 150 200 250 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 F in al setti n g ti m e (m in ) Dosage of admixture (wt%) PCE1 PCE2 PCE3 CA 0.2CA+0.2PCE1 0.2CA+0.2PCE2 0,1 1 10 100 1000 0 50 100 150 200 250 Y iel d str ess τ0 (Pa) Time (min) SAC 0.2PCE1 0.2PCE2 0.2PCE3 0.2CA 0.2CA+0.2PCE1 0.2CA+0.2PCE2 0% 20% 40% 60% 80% 100% 120% 0 20 40 60 80 100 120 A d so rp ti o n (%) Time (min)

PCE1 in 0.2CA+0.2PCE1 PCE1 in 0.2PCE1 CA in 0.2CA+0.2PCE1 CA in 0.2CA

Hydration and rheology of sulfoaluminate-belite cements (SAC) in

presence of polycarboxylate superplasticizers (PCE) and citric acid

R. Belhadi*, A. Govin & P. Grosseau

Mines Saint-Etienne, Univ Lyon, CNRS UMR 5307 LGF, Centre SPIN, Departement PMMG, F - 42023 Saint-Etienne France

* rachid.belhadi@emse.fr

1. Context

 Effect of the chemical structure of PCE on the

hydration and rheology of reactive SAC

 Commercial SAC (i.tech ALI CEM)  Citric acid (99,5% Honeywell)

 3 polycarboxylates ethers (PCE1, PCE2 and PCE3)

Phase composition of SAC (%) C₄A₃$ C₂S C$ 49,3 15,1 23,5 Mw (g/mol) Charge density (mmol/g) P N n PCE1 48300 0,79 45 5 12 PCE2 138600 0,3 114 5 15 PCE3 11900 0,96 17 2,5 115 EN 196-3 Standard

SAC

C₄A₃$ C₂S C$

Greener than OPC Poor workability

+

PCE

Dispersing effectiveness Rheological properties

+

Citric acid

(CA)

Hydration delay

??

Dispersing effectiveness of PCE may be affected by :

Total Organic Carbon Ionic Chromatography Mi ni -Cone V ic at Needl e

Initial Setting Final Setting

 CA delays significantly the Initial and Final setting times

 PCE + CA  Initial & Final setting: PCE+CA > CA > PCE

𝜏₀ = 225𝜌𝑔𝑉 2 128𝜋2_𝑅5_{(1 +} 225 128𝜋 3𝑉𝑅−3)

2. Objectives

3. Materials

4. Methods

6. Conclusions & Perspectives

PCE CA + PCE

Adsorption of CA  from 97% to 87% in presence of PCE1 The amount of PCE adsorbed decreases in presence of CA

+

+

SAC

Reactivity of SAC

Competitive adsorption between Citric acid and PCE Adsorption of PCE + CA Adsorption of CA Chemical Analysis Centrifugation Measuring Setting time Measuring Spread flow Calculating Yield Stress

Understand the :

 PCE1 + CA ≈ PCE2 + CA

  % in PCE  Initial & Final setting: PCE1 > PCE2 ≈ PCE3

 Short setting time of SAC without admixtures _{Fast hydration of}

C₄A₃$ with C$

Ettringite C₆A₃$H₃₂

Slight increase in initial fluidity Workability retention over time CA

CA + PCE

 Initial fluidity compared to SAC

 Workability retention over time

Affinity of PCE with SAC : PCE1 > PCE2 > PCE3 Maximum adsorption : PCE1 > PCE3 > PCE2

the better dispersing efficiency of PCE1

 Effect of combination of citric acid with PCE

on hydration and rheology of reactive SAC

The amount of PCE adsorbed increases over time

Competitive adsorption

 Initial fluidity

compared to PCE alone

Setting time : PCE1 > PCE2 ≥ PCE3

Dispersing effectiveness : PCE1 > PCE2 > PCE3 Adsorption : PCE1 > PCE2 > PCE3

CA Setting time : CA > PCE

Adsorption : CA > 97% >> PCE

 Workability retention over time

Effect

Adsorption : CA > 87% > PCE & PCE < PCE alone

 Initial fluidity compared to PCE alone

 Workability retention over time CA reduces the amount

of ettringite at early age

 The amount of PCE consumed by intercalation

 Rheological properties TGA & DRX are required to

follow the hydration

Hypothesis

+

Fast setting

_

_

p a b N=a+b n

5. Results

Fast  𝜏₀ Fast  workability

 𝜏₀  Initial fluidity PCE

Initial 𝜏₀ with PCE1 < PCE2 < PCE3

!

Dispersion efficiency of PCE1 > PCE2 > PCE3

R : Spread radius 𝜌 : Paste density

V : Mini-cone volume

PCE PCE + CA

Setting-Time

Spread flow / Yield stress

Adsorption

Setting time : PCE + CA > CA > PCE 0% 20% 40% 60% 80% 100% 120% 0 20 40 60 80 100 120 A d so rp ti o n (%) Time (min)

PCE2 in 0.2CA+0.2PCE2 PCE2 in 0.2PCE2 CA in 0.2CA+0.2PCE2 CA in 0.2CA

the lowest dispersing efficiency of PCE3 Explain