Effect of Citric Acid and Polycarboxylate Superplasticizers (PCE) on Hydration and Rheology of Sulfoaluminate Cement

Rachid Belhadi (1, 2) , Alexandre Govin (1, 2) , Phillipe Grosseau (1, 2)

1 SPIN-ENSMSE - Centre Sciences des Processus Industriels et Naturels
2 LGF-ENSMSE - Laboratoire Georges Friedel

The production of normal portland cement (NPC) accounts for about 5%-7% of the total man-made CO₂ emissions. One of the low CO₂ alternatives to NPC is sulfoaluminate cement (CSA), mainly composed of ye’elimite (C₄A₃S), belite (C₂S) and sulfate source (CS or CSH₂). Its main hydrated phase is ettringite (C₆A₃SH₃₂). CSA are known for their poor workability and their short setting time, which require the use of superplasticizers and retarders. The aim of this work is to investigate: (i) the effect of citric acid and polycarboxylate superplasticizers (PCE) on the hydration and rheology of CSA; and (ii) the effect of citric acid on the dispersing effectiveness of PCEs. Two PCEs, with the same chemical structure and different molecular structure, were studied. Isothermal calorimetry and thermogravimetric analysis (TGA) were used to describe the hydration process, while rheological properties were characterized with a flow test. Adsorption measurements were carried out with total organic carbon analyzer and ionic chromatography. The results show that the combination of citric acid and PCE allows better retention of workability over time. However, a competitive adsorption between citric acid and PCE decreases the initial dispersion.

Mots clés: Polycarboxylate Superplasticizers; Sulfoaluminate Cement; Citric Acid; portland cement

Domaines: Génie des procédés

Rachid Belhadi, Alexandre Govin, Phillipe Grosseau. Effect of Citric Acid and Polycarboxylate Superplasticizers (PCE) on Hydration and Rheology of Sulfoaluminate Cement. 11^TH ACI/RILEM International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete (ICCM2021), Université de Sherbrooke; Université de Toulouse III - Paul Sabatier; Lmdc Laboratoire Matériaux et Durabilité des Constructions Toulouse; CRIB, Jun 2021, Sherbrooke, Canada. pp.408 à 417 / SP-349-28. ⟨hal-03697380⟩