Bone ash reinforced geopolymer composites

Abdul W. Bhuiya, Michael Hu, Kaushik Sankar, Patrick F. Keane, Daniel Ribero, Waltraud M. Kriven

Research output: Contribution to journalArticlepeer-review


Potassium-based, geopolymer composites were made with BASF® metakaolin and Mymensingh clay-derived metakaolin from Bangladesh. Since the natural Mymensingh clay contained 40 wt.% quartz, this same amount of quartz particulates was added to the BASF® metakaolin to make a synthetic analog of the natural calcined clay. By analogy with bone china, bone ash or calcined hydroxyapatite (5CaO•3P2O5 or “HA”) particles, having a Ca: P ratio of 3.3:1, were added to make the three types of geopolymer-based composites described above. For less refractory particulate additions, dicalcium phosphate (DCP) (2CaO•P2O5 or “DCP”) particles, having a Ca: P ratio of 2:1, were also added to another set of geopolymers. The ambient temperature compressive and flexural strengths were measured for all of the geopolymer composites. The HA or DCP reinforced geopolymer composites were fabricated and heat-treated to 1150°C/1 h, after which they were converted to their mineralogical analogs. Their mechanical properties of compressive and 3-point flexural strengths were again measured. Flexural strengths of 22.42 ± 11.0 MPa and 31.97 ± 8.3 MPa were measured in 1 × 1 × 10 cm3 heat-treated geopolymer bars reinforced with 10 wt.% of DCP and in geopolymer reinforced with 10 wt.% DCP +40 wt.% quartz additions, respectively. Significant improvements to ambient temperature properties were observed due to the self-healing effect of the flowing amorphous DCP, whose presence was verified by SEM. The geopolymer samples exhibited reduced water absorption (WA) (on a percentage dry weight basis) of within 0.03-0.5% after being heated at 1100℃/1 h and 1125℃/1 h, as compared with those at room temperature, which varied between 2.56% and 7.89%.

Original languageEnglish (US)
Pages (from-to)2767-2779
Number of pages13
JournalJournal of the American Ceramic Society
Issue number6
StatePublished - Jun 2021
Externally publishedYes


  • Mymensingh clay
  • amorphous self-healed geopolymer composites
  • bone ash
  • calcined hydroxyapatite
  • dicalcium phosphate
  • geopolymer
  • metakaolin

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry


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