Formulation of mechanical properties of hybrid fiber alkali-activated concretes by data analysis

In this study, ground blast furnace slag (GBFS) and waste volcanic rock dust (RD) produced in a natural stone processing plant were used as binders. The binders were activated with Sodium Hydroxide (NaOH) and Sodium Silicate (Na2SiO3) to produce two types of concrete: alkali-activated concrete without fibers (AAC) and alkali-activated concrete with fibers (FAAC). In the production of concrete, steel and polyester fibers were used separately and hybrid at 0.25%, 0.50%, 0.75% and 1.0% by volume and a total of 117 15x15x15 cm cube specimens were produced. The mechanical properties of the specimens were evaluated by concrete surface hardness, ultrasonic pulse velocity and concrete compressive strength tests at 3, 7 and 28 days. The results obtained using non-destructive test methods were matched with concrete compressive strength values using various empirical formulas. Calculated concrete compressive strength values and actual concrete compressive strength values were compared using data analysis method. As a result, it was observed that there was a very significant correlation between the experimental compressive strength and the combined method in which 7-day surface hardness and ultrasound transmission rate were used together to calculate the compressive strength.