Investigation of fresh mortar properties of alkali activated mortars produced with Elazığ ferrochrome slag

In this thesis study; the use of borax and superplasticizer additives has been investigated to solve the problems of rapid workability loss and low setting times, which hinder the use of alkali-activated slag binders in applications. For the production of alkali activated mortar, 90%, 80%, 70% by weight Elazığ ferrochrome slag and 10%, 20% and 30% by weight class F fly ash were used. Solid phase sodium hydroxide (NaOH) (18 and 22 molarity) and liquid phase sodium silicate solution (Na2SiO3) were used as alkali activators. The ratio of NaOH/Na2SiO3 was kept at a constant value of 1/2. Activator/binder ratios of 0.35, 0.40 and 0.45 were taken. The additives were preferred at 0%, 3% and 6% by weight. The selected parameters and their levels were optimized by the Taguchi method and the best mixing ratios were determined. On fresh mixtures setting times and workability tests were performed. The produced alkali-activated mortar samples were cured at 90oC for 24 hours and at the end of 7 and 28 days, compressive strength, bending strength, unit weight, ultrasound transmission rate and capillarity tests were carried out. Obtained test results were analysed by Taguchi method and optimum parameter levels were determined. The crystal structure of the samples determined by applying SEM-EDS-XRD analyses for microstructure investigations. According to the data obtained, it has been determined that borax and superplasticizer additives have a setting retarding effect on alkali-activated mixtures and provide positive contributions on workability. The highest compressive strength value was obtained as 24.27 MPa.