Influence of Chemical Admixtures on Properties of Alkali-Activated Slag-Based Mortars

Abstract:

Alkali-activated slag (AAS) based binders can have similar or even better properties in terms of mechanical performance, durability and chemical resistance than ordinary Portland cement (PC), but AAS binders also show some drawbacks, especially high shrinkage and poor rheology. Improvement of these features in the case of PC binder is well established, but a lot of conventional admixtures like superplasticizers do not work in AAS. The influence of shrinkage reducing admixture (SRA) and airentraining admixture (AEA) on mechanical properties, workability and shrinkage was investigated in this study. These admixtures were used in the different dosages in the range of 0–2.0% (by mass of slag). With increasing content of both admixtures compressive and flexural strength decreased. Similar effect was observed for workability. On the other hand, promising results in respect of shrinkage reduction were obtained particularly for SRA, where its 1.0% dose reduced drying shrinkage of the reference mortar by more than 70%. Only slight shrinkage reduction was observed for 0.50% of AEA.

• Periodical: Advanced Materials Research (Volume 1124)
• Pages: 37-42
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1124.37
• Online since: September 2015
• Authors: Vlastimil Bílek Jr.*, Lukáš Kalina, Jan Koplík, Radoslav Novotný, Miroslava Hajdúchová, Tomáš Opravil
• Keywords: Air-Entraining Admixture, Alkali-Activated Slag, Shrinkage, Shrinkage-Reducing Admixture, Strength, Workability

References

[1] P. -C. Aïtcin, S. Mindess, Sustainability of concrete, New York: Spon Press, 2011, ISBN 978-0-203-85663-5.

DOI: 10.1016/b978-0-08-100693-1.15003-9

[2] F.G. Collins, J.G. Sanjayan, Workability and mechanical properties of alkali activated slag concrete, Cem. Concr. Res. 29 (1999) 455-458.

DOI: 10.1016/s0008-8846(98)00236-1

[3] T. Bakharev, J.G. Sanjayan, Y. -B. Cheng, Resistance of alkali-activated slag concrete to acid attack, Cem. Concr. Res. 33 (2003) 1607-1611.

DOI: 10.1016/s0008-8846(03)00125-x

[4] T. Bakharev, J.G. Sanjayan, Y. -B. Cheng, Sulfate effect on alkali-activated slag concrete, Cem. Concr. Res. 32 (2002) 211-216.

DOI: 10.1016/s0008-8846(01)00659-7

[5] C. Shi, P. Xie, Interface between cement paste and quartz sand in alkali-activated slag mortars, Cem. Concr. Res. 28 (1998) 8787-896.

DOI: 10.1016/s0008-8846(98)00050-7

[6] R. San Nicolas, S.A. Bernal, R. Mejía de Gutiérrez, J.S.J. van Deventer, J.L. Provis, Distinctive microstructural features of aged sodium silicate-activated slag concretes, Cem. Concr. Res. 65 (2014) 41-51.

DOI: 10.1016/j.cemconres.2014.07.008

[7] M. Palacios, F. Puertas, Effectiveness of Mixing Time on Hardened Properties of Waterglass-Activated Slag Pastes and Mortars, ACI Mater. J., 108 (2011) 73-78.

DOI: 10.14359/51664218

[8] A.A. Melo Neto, M.A. Cincotto, W. Repette, Drying and autogenous shrinkage of pastes and mortars with activated slag cement, Cem. Concr. Res. 38 (2008) 565-574.

DOI: 10.1016/j.cemconres.2007.11.002

[9] S. Aydin, A ternary optimisation of mineral additives of alkali activated cement mortars, Constr. Build. Mater. 43 (2013) 131-138.

DOI: 10.1016/j.conbuildmat.2013.02.005

[10] J.S. Alcaide, E.G. Alcocel, F. Puertas, R. Lapuente, P. Garcés, Carbon fibre-reinforced, alkali-activated slag mortars, Materiales de Construcción. 57 (2007) 33-48.

DOI: 10.3989/mc.2007.v57.i288.63

[11] N. Marjanović, M. Komljenović, Z. Baščarević, V. Nikolić, R. Petrović, Physical–mechanical and microstructural properties of alkali-activated fly ash–blast furnace slag blends, Ceram. Int. 41 (2015) 1421-1435.

DOI: 10.1016/j.ceramint.2014.09.075

[12] A.R. Sakulich, D.P. Bentz, Mitigation of autogenous shrinkage in alkali activated slag mortars by internal curing, Mater. Struct. 46 (2013) 1355-1367.

DOI: 10.1617/s11527-012-9978-z

[13] M. Palacios, F. Puertas, Effect of shrinkage-reducing admixtures on the properties of alkali-activated slag mortars and pastes, Cem. Conr. Res. 37 (2007) 691-702.

DOI: 10.1016/j.cemconres.2006.11.021

[14] C. Bilim, O. Karahan, C.D. Atiş, S. İlkentapar, Influence of admixtures on the properties of alkali-activated slag mortars subjected to different curing conditions, Mater. Des. 44 (2013) 540-547.

DOI: 10.1016/j.matdes.2012.08.049

[15] T. Bakharev, J.G. Sanjayan, Y. Cheng, Effect of admixtures on properties of alkali-activated slag concrete, Cem. Concr. Res. 30 (2000) 1367-1374.

DOI: 10.1016/s0008-8846(00)00349-5

[16] F. Rajabipour, G. Sant, J. Weiss, Interactions between shrinkage reducing admixtures (SRA) and cement paste's pore solution, Cem. Concr. Res. 38 (2008) 606-615.

DOI: 10.1016/j.cemconres.2007.12.005