An experimental study on fracture energy of alkali activated slag composites incorporated different fibers

Abstract

This paper intended to comparatively investigate the fracture behavior of alkali activated slag concrete (AASC) containing glass fiber (GF), basalt fiber (BF) and polypropylene fiber (PP). Sodium hydroxide (8 mol, 10 mol and 12 mol aqueous solutions) and sodium silicate, and three different fiber dosages (1 kg/m³, 2 kg/m³ and 3 kg/m³) were used in the production of the fiber reinforced alkali activated slag composites (FRAASC). Additionally, a relatively low activation temperature of 60 °C as a curing condition to activate the AASC specimens was adopted in terms of ensuring energy-effective production in the study. Three-point bending tests were conducted to determine the fracture energy (Gf) values on notched beam specimens. In the study, the Gf values were measured by calculating the area under the curve of load and crack mouth opening displacement (CMOD) values. In addition, destructive and non-destructive tests such as splitting tensile strength, compressive strength, dynamic modulus of elasticity (DMoE), ultrasonic pulse velocity, density and porosity were applied onto the hardened AASC specimens. Microstructure analysis was carried out by Energy-Dispersive X-ray Spectroscopy (EDX) and Scanning Electron Microscopy (SEM). As a result, usage of GFs, BFs and PPs increases the energy dissipation capacity and ductility of FRAASCs. An increase of 84% for Gf values was observed from the FRAASC specimens having 8 molarity of sodium hydroxide aqueous solutions with polypropylene fibers. Based on the test results, it can be clearly said that using of glass, basalt and polypropylene fiber is improving the ductile behavior of eco-efficient slag based alkali-activated composites.