Geopolymer ultrahigh performance concrete: Material and performance
May 27-June 1, 2018
During the last two decades, considerable progress has been made in the development of ultra-high-performance concrete (UHPC) with ordinary Portland cement (OPC). UHPC represents a major development step over high performance concrete (HPC), through the achievement of very high compressive strength (over 20,000 psi or 140 MPa) and superior durability due to very low permeability compared to high-performance concrete; in some cases, fibers are included to achieve improved ductility. Despite these performance advantages, deployment of Portland cement-based UHPC has been slow, in part due to the relatively high compared to that of conventional concrete components. In addition, the higher content of Portland cement in UHPC, high temperature steam curing, and use of relatively large amounts of superplasticizers increase the cost and CO2 footprint. Geopolymer-based UHPCs have the potential for significant advantages over comparable OPC-based materials. We have developed a range of low-cost, low-CO2 footprint, geopolymer UHPC (GUHPC) formulations. The main characteristics of these GUHPCs include: 1) Increased homogeneity by excluding aggregates >9.5mm, 2) Increased packing density through use of micro- and nano-particles, 3) Very low water-to-binder ratio through chemically tailored activator compositions and use of intensive mixing; 4) Composite binders yielding hybrid calcium aluminosilicate hydrate (C-A-S-H) and alkali aluminosilicate hydrate (A-A-S-H) gels to improve product properties; and 5) Regulation of set times using a very effective inorganic retarder.
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Weiliang Gong, Carole Palfray, Nathan Masera, Hui Xu, Werner Lutze, and Ian L. Pegg, "Geopolymer ultrahigh performance concrete: Material and performance" in "International Conference on Alkali Activated Materials and Geopolymers: Versatile Materials Offering High Performance and Low Emissions", J. Provis, University of Sheffield C. Leonelli, Univ. of Modena and Reggio Emilia W. Kriven, Univ. of Illinois at Urbana-Champaign A. Boccaccini, Univ. of Erlangen-Nuremberg A. Van Riessen, Curtin University, Australia Eds, ECI Symposium Series, (2018). http://dc.engconfintl.org/geopolymers/9