RETRACTED: Effect of micro polypropylene fibres and nano TiO2 on the fresh- and hardened-state properties of geopolymer concrete

Abstract

• Effect of nano-TiO 2 on the mechanical properties, in addition to slump of GPC; • Effect of MPPF on the mechanical characteristics of FA-based GPC. • Accurate models to predict the mechanical behaviour of MPPF-reinforced FA-based GPC. This study intends to assess the influence of micro polypropylene fibres (MPPF) and nano-TiO 2 on the fresh- and hardened-state properties of fly ash (FA) based geopolymer concrete (GPC). 15 concrete mixes were produced and the slump, compressive, splitting tensile and flexural strengths, sorptivity, sulphate and chloride attack were measured. Five TiO 2 incorporation ratios were used: 0%, 1%, 2%, 3%, 4% and 5% in terms of weight. Additionally, three MPPF contents were added in terms of volume: 0%, 1% and 2%. One sample was selected as a control specimen with no TiO 2 and MPPF. Furthermore, new models were developed to predict the mechanical properties of GPC produced by different TiO 2 and MPPF contents. The results showed that the mechanical properties and resistance of FA-based GPC against sulphate and chloride attacks were considerably improved with the use of nano-TiO 2 and these properties were further enhanced when MPPF were also added. Therefore, using 5% nano-TiO 2 with 2% MPPF improved the resistance of GPC against sulphate and chloride attacks respectively by 53% and 36%. In addition, the proposed models, with a high agreement with the experimental results, are useful tools to predict the mechanical properties of FA-based GPC produced with different nano-TiO 2 and MPPF contents.