6TH International Congress on Technology - Engineering - Kuala Lumpur3 - Malaysia (2018-07-19)

The Effect Of Carbon Fibers On Rheological And Mechanical Properties Of Metakaolin-slag Geopolymer Binder

This study investigates the effects of carbon fibers addition on rheological behaviour and final mechanical strength of geopolymer binder. The neat binder and two binders filled by carbon fibers as three representatives of different geopolymer binder compositions. The neat binder was synthesized by alkalination of calcined claystone powder and milled blast furnace slag by potassium silicate solution. The binders filled by carbon fibers were prepared by the same procedure as neat binder and 20wt% of short or milled fibers were added to prepared binder. The length of fibers were 4 mm and below 0.5 mm respectively for determination of effects on rheological and mechanical properties. The rheological properties were determined in accordance to flow properties by rotational rheometry and by strain controlled small amplitude oscillatory rheometry measurements of hardening process. The final properties were documented by measurements of flexural strength after 3, 28 and 280 days and by optical and scanning electron microscopy. The results indicate that milled carbon fibers has mild effect on flow properties compared to neat binder. In contrast, 4 mm long carbon fibers increases the viscosity significantly by interlocking of individual fibers and noticeably decreases workability. From opposite point of view the reinforcement effect of milled fibers is not considerable and fibers of this length only slightly improves the stress strain behaviour. Contrary to this, the 4 mm improves the stress strain characteristic and ultimate flexural strength of neat geopolymers binder approximately 5 times. Keywords: Geopolymer, Binder, Carbon fiber, Rheology, Strength
David Rieger, Tom?? Kov???k, Michal Pola, Petr Fran?e, Jaroslav Kadlec