Prediction of Torsional Strength for Very High Early Strength Geopolymer

  • Woraphot PRACHASAREE Prince of Songkla University
  • Abideng HAWA
Keywords: torsion, strength, geopolymer, modulus of rupture, concrete


Very early high strength geopolymers are gaining acceptance as alternative repair materials for highways and other infrastructure. In this study, a very rapid geopolymer binder based on Metakaolin (MK) and Parawood ash (PWA), developed by the authors, was experimentally tested and a prediction model for its torsional strength is proposed. The geopolymer samples were subjected to uniaxial compression, flexural beam, and torsion tests. The modulus of rupture and torsional strength in terms of compression strength were found to be well approximated by 0.7(f’c)1/2 and 1/7(x2y) (f’c)1/2, respectively. Also an interaction relation to describe combined bending and torsion was developed in this study. In addition, the effects of aspect ratio (y/x) were studied on both torsional strength and combined bending and torsion. It was found that an aspect ratio of y/x = 3 significantly reduced the torsional resistance, to about 50 % of the torsional strength of a square section.