Supersulfated binders based on volcanic raw material: Optimization, microstructure and reaction products

• Published in: Construction & building materials Vol. 176; pp. 145 - 155
• Main Authors: Cabrera-Luna, K., Maldonado-Bandala, E.E., Nieves-Mendoza, D., Escalante García, J.I.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 10-07-2018; Elsevier B.V
• Subjects: Analysis; Compressive strength; Concrete curing; Experimental design; Hydration products; Mechanical properties; Microstructures; Portland cement; Supersulfated cement; Sustainable cements; Temperature; Thermal properties; Volcanic material; Mexico; Volcanic material; Experimental design; Hydration products; Sustainable cements; Supersulfated cement; Compressive strength; Microstructures
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2018.05.024

•Volcanic materials are useful precursors to formulate supersulfated binders.•C-S-H and ettringite are the main hydration products.•20% Portland cement contents favor strength, CaSO4 is essential to improve strength.•Anhydrite is better to improve strength than hemihydrate.•The statistically predicted 28 and 90 days strengths were experimentally confirmed.
The characterization and optimization of supersulfated binders based on a volcanic material was carried out by Taguchi orthogonal array experimental design, investigating the effects of four factors: type of calcium sulfate, % calcium sulfate, %Portland cement and initial curing temperature. The binders increased strength over time. The statistically defined optimum formulation was: 70%volcanic material-10%Anhydrite-20%Portland cement and curing 22 h at 60 °C then at 20 °C; the predicted and confirmed 28-day strength was 20.2–20.6 MPa; optimum conditions are discussed for other ages. The microstructures and chemical composition of hydration products (EDS) and XRD indicated the formation of C-S-H and ettringite as the main hydration products.