Thesis (PhD) - Cyprus International University. Institute of Graduate Studies and Research Civil Engineering Department

Includes bibliography (sheets 173-200)

ABSTRACT The goal of this research is to see how nanomaterials like nanoalumina and nanosilica affect the mechanical and durability of fiber reinforced alkali-activated mortars (FRAAM). PPF was added to the binders at 0.5 and 1% by volume. Central composite design (CCD) for mix proportions is provided by design-expert software. Variables are divided into three steps using this technique. A large number of mixtures were made and assessed, each with different quantities of variables. In this experiment, the major binders were 50% fly ash (FA) and 50% ground granulated blast slag (GGBS). The sodium hydroxide (NaOH) concentration was 12 molarity, and the alkali activated solution to binder ratio was 0.5. The proportion of sodium silicate to sodium hydroxide was 2.5. At ages of 7, 28, and 90 days, the cubic specimens and prisms were examined in an ambient environment at 23±3 ℃ room temperature. The compressive and flexural strengths, as well as fresh qualities such as flowability and alkali activator mortar unit weight, were used to determine the mechanical performance of AAM. In addition, the microstructure analysis and durability performance were assessed. The AAM without fibers and nanoparticles had a higher flow rate than the other combinations, according to the tests. All mixes, however, had moderate flowability ranges. 2% NA provided the best compressive strength, while a mixture of 1 percent NS and 1 percent PPF provided the best flexural strength. A mixture of 2% nano-silica and 1% polypropylene fiber was used to reduce water absorption. The sorptivity of the mixture of 2% nano-silica, 1% nano-alumina, and 0.5 % polypropylene fiber was the lowest. Furthermore, the microstructure study revealed that the nanomaterials significantly improved the matrix and increased the porosity of the matrix. Feasibility have Comparisons between the different humidity 60%-98% of at 24±4 Cº and strength behaviors of alkali activated mortar with different curing ages. The experimental results revealed that the length change of AAM decreased with the addition of polypropylene fiber and nanomaterials. The samples without PPF with nano material achieved better performance of length change of AAM and the length of samples decreased more when samples nanomaterials separately. Even more; samples contain both nanomaterials have better than samples contain using a nano SiO2 and nano Al2O3, discretely. The performance of alkali activator mortar contain polypropylene fiber shows higher resistance under chemical attacks and contain both fiber and nano materials achieved higher chemical resistance than specimens contain nano materials separately and specimens contain 2% NA or 2% NS.