Experimental study on autogenous deformation of metakaolin based geopolymer

Author(s): Zhenming Li, Peng Gao and Guang Ye
Paper category: Proceedings
Book title: Proceedings of the 2nd International RILEM/COST Conference on Early Age Cracking and Serviceability in Cement-based Materials and Structures Volume 1
Editor(s): Stéphanie Staquet and Dimitrios Aggelis
ISBN:978-2-35158-199-5
e-ISBN:978-2-35158-198-8
Publisher: RILEM Publications SARL
Publication year: 2017
Pages: 209-214
Total Pages:
Language : English

Abstract: Geopolymer is considered as an important alternative to ordinary Portland cement. Geopolymer can be synthesized by alkali-activation of various aluminosilicates, among which metakaolin is one of the most widely studied precursors. When geopolymer serves as a binding material in construction engineering, autogenous deformation has to be carefully considered since it may induce microcracking or macrocracking and impair the concrete quality. However, till now no published article can be found concerning this property of metakaolin based geopolymer (MKG). In this study, the autogenous deformation of MKG pastes synthesized from different metakaolins (MK1 and MK2) and activators is experimentally investigated. The results show that MKG can exhibit various autogenous deformation behaviors in different ages dependent on the property of the raw material and the chemical composition of the activator. In early age, MKG made from MK1 shows high autogenous shrinkage while MKG made from MK2 shows lower autogenous shrinkage or even autogenous expansion. In
later age, the autogenous deformation behavior of MKG is mainly determined by the SiO2 content of the alkali activator, with high SiO2 content resulting in autogenous shrinkage while low or zero Si content resulting in autogenous expansion. For the two high-silica-activated mixtures, whose final setting times are acceptable, the autogenous shrinkage mechanism is explored, and the pore pressure (capillary pressure or disjoining pressure) is excluded from the possible driving forces.

Online publication : 2017
Publication type : full_text
Public price (Euros) : 0.00