## 1 Introduction  
The emission of greenhouse gases from various sectors, including transport, energy supply, residential, businesses, industrial processes, agriculture, etc., has appeared as an extreme obstacle that significantly influences global climate change. The Portland cement (PC) manufacturing process is in charge of a large amount of carbon dioxide (CO\({}_{2}\)) emission with up to 10% of CO\({}_{2}\) emission globally. Geopolymer material comprised alkaline solution and alumino-silicate sources to create a gel called N-A-S-H, which was reported to cut carbon footprint by 90% compared to the production of PC [1]. Depending upon local resources and availability, solid aluminosilicate precursors can be in natural forms such as zeolite, amphibide, whales, or industrial by-products such as fly ash, metakaolin, red mud, waste glass, etc. [2, 3]. Alumina (Al\({}_{2}\)O\({}_{3}\)) as well as silica (SiO\({}_{2}\)) are essential components of geopolymer materials even in natural or by-products forms. These two factors play a significant role in the hardening of geopolymer materials. They produce the N-A-S-H gel which is in charge of properties of the final product. Based on [PERSON] et al. [4], the geopolymerization has various step such as dissolution, speciation equilibrium, gelation, reorganization, polymerization, and hardening. Aluminum (Al) and silicon (Si) are released during the dissolution step. The final Si-rich gel is formed by reaction between the Si in the solution and initial Al-rich gel. The main product of this process is the N-A-S-H gel [5]. Geopolymer materials have received much more attention in the construction field due to their high chemical resistance and good mechanical properties. [PERSON] [6] compared the compressive strength of Portland cement concrete (PCC) and fly ash-based geopolymer concrete (FAGC) cured at 80 \({}^{\circ}\)C for 24 h and showed that FAGC had higher tensile strength and early compressive strength compared to PCC. [PERSON] [7] and [PERSON] [8] also stated that the elevating curing temperature would speed up the dissolution, polymerization, and reprecipitation process of the geopolymerization reaction. Additionally, it showed the ability to resist freeze-thaw and high temperature conditions compared to conventional concrete. [PERSON] [9] proved that geopolymer grout offers a heat resistance advantage, where its compressive strength is still maintained at 800 \({}^{\circ}\)C, while that of PC grout is lost entirely. Incorporating steel reinforcing bars into geopolymer concrete for structural components such as columns, beams, and external walls has drawn tremendous attention from many scholars [10; 11; 12; 13; 14; 15; 16; 17]. Their studies focused on the mechanical properties such as tensile and bond strength of reinforced FAGC. Reinforced FAGC with deformed steel bars were reported to attain higher splitting tensile strength than that of PCC [18]. One of the most crucial factors to identify the performance of reinforced concrete materials is bond property, which is considered as the stress transfer along the longitudinal direction of the reinforcing bars to the concrete matrix [19]. Similar to conventional reinforced concrete, reinforcing bar diameter and texture, splice length, concrete cover thickness, and strength of concrete play a significant role in the bond performance (such as failure modes and crack patterns of reinforced FAGC beams) [20]. In this regard, [PERSON] et al. [13] investigated the bond strength of steel reinforcing bars, which included plain and ribbed ones with a nominal diameter of 16 mm, one embedded in FAGC using a beam-end pullout test, and ones worked with eight strain gauges. It was suggested that the bond strength between reinforcing bars and FAGC was up to 21% higher than that with conventional concrete, owing to the excellent adhesion and compact interface of the steel bars and geopolymer concrete matrix.