Impact of the Fly Ash/Alkaline Activator Ratio on the Microstructure and Dielectric Properties of Fly Ash KOH-Based Geopolymer
Author:
Yadav Meenakshi12ORCID, Saini Neha12, Kumar Lalit12, Singh Vidya Nand12ORCID, Jagannathan Karthikeyan3ORCID, Ezhilselvi V.12ORCID
Affiliation:
1. Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India 2. CSIR-National Physical Laboratory, Indian Reference Materials Division (BND), Dr. K. S. Krishnan Marg, New Delhi 110012, India 3. Department of Physics, SRM Institute of Science and Technology, Vadapalani Campus, No. 1 Jawaharlal Nehru Road, Vadapalani, Chennai 600026, India
Abstract
Geopolymer materials, alternatives to cement that are synthesized using industrial byproducts, have emerged as some of the leading champion materials due to their environmentally friendly attributes. They can significantly reduce pollution by utilizing a plethora of waste products and conserving natural resources that would otherwise be used in the production of conventional cement. Much work is being carried out to study geopolymers’ characteristics under different conditions. Here, a geopolymer derived from fly ash (FA) was synthesized using a combination of sodium silicate and potassium hydroxide (KOH) (2.5:1 ratio) as an alkali activator (AA) liquid. The FA/AA ratios were optimized, resulting in distinct geopolymer samples with ratios of 1.00, 1.25, 1.50, and 1.75. By adjusting the contribution of alkaline liquid, we investigated the impacts of subtle changes in the FA/AA ratio on the morphology and microstructure using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. The FESEM analysis illustrated a mixed matrix and morphology, with the sample with a ratio of 1.00 displaying consistently fused and homogenous morphology. The XRD results revealed the prevalent amorphous nature of geopolymer with a few crystalline phases of quartz, sodalite, hematite, and mullite. An electrical study confirmed the insulating nature of the geopolymer samples. Insulating geopolymers can provide energy-efficient buildings and resistance to fire, hurricanes, and tornadoes. Additionally, using KOH as a part of the alkali activator introduced a less-explored aspect compared to conventional sodium hydroxide-based activators, highlighting the novelty in the synthesis process.
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