The Effect of Nano-Silica and Nano-Alumina with Polypropylene Fiber on the Chemical Resistance of Alkali-Activated Mortar

This study investigates the simultaneous effect of nano-silica and nano-alumina with and without polypropylene fiber on the chemical-resistant of alkali-activator mortar (AAM) exposed to (5% Sulfuric Acid, 5% Magnesium Sulphate, and 3.5% Sodium chloride) attack. Design-expert software provided the central composite design (CCD) for mixed proportions. Nano-silica (NS) and nano-alumina (NA) at 0, 1%, and 2%, and with polypropylene fiber (0, 0.5%, and 1%) were used in the production of AAM. The alkali activator mortar mixes were created using an alkaline activator to binder ratio of 0.5. The binder materials include 50% fly ash Class F (FA) and 50% ground granulated blast furnace slag (GGBS). A sodium silicate solution (Na2SiO3) and sodium hydroxide solution (NaOH) were combined in the alkaline activator at a ratio of 2.5 (Na2SiO3/NaOH). The mechanical properties of AAM were tested via compressive strength and flexural strength tests. The results show that the acid attack, more than the sulphate and chloride attacks, significantly influenced the AAM. The addition of both nanomaterials improved the mechanical properties and chemical resistance. The use of nanomaterials with PPF showed a superior effect, and the best results were indicated through the use of 2%NA–1%PPF.