## 2 Experimental Program  
### Materials  
All the tested beams were constructed using ordinary Portland cement (OPC) 42.5 grade, which has a specific gravity of 3.10 g/cm\({}^{3}\) and an average particle size of 20.67 \(\upmu\)m. The chemical composition of the OPC is shown in Table 1. In this investigation, natural river sand was used as the fine aggregate. The sand had a specific gravity of 2.42 g/cm\({}^{3}\), water absorption of 1.92%, and a fineness modulus of 2.25. As a coarse aggregate, natural crushed stone with a nominal maximum size of 12.5 mm was employed. The coarse aggregate had a specific gravity of 2.78 g/cm\({}^{3}\) and water absorption of 1.56%. Concrete was made using tap water, with a water-to-cement ratio of 0.42 in this investigation. It was necessary to utilize a superplasticizer to ensure the required workability. To improve the workability of concrete, this superplasticizer, which complies with ASTM C494 type F [49; 50], is made of synthetic resins and added at a dose of 1.5% by weight of cement. The main bottom and top longitudinal deformed bars of all tested beams with a diameter of 12 mm and 10 mm, respectively, and stirrups with diameters of 8 mm. Sika Wrap\({}^{\otimes}\)-430 G of Sika Egypt, as shown in Figure 1a, was used as unidirectional GFRP laminates, which have a density of 2.56 g/cm\({}^{3}\), a thickness of 0.168 mm, a tensile strength of 2500 N/mm\({}^{2}\), and modulus of elasticity equal to 72,000 N/mm\({}^{2}\), according to the manufacturing sheet. \begin{table}
\begin{tabular}{c c c} \hline
**Composition** & **OPC** & **FA** \\ \hline \multicolumn{3}{c}{Chemical properties} \\ \hline SiO\({}_{2}\) & 19.39 & 57.2 \\ Al\({}_{2}\)O\({}_{3}\) & 4.13 & 24.4 \\ CaO & 55.66 & 2.2 \\ Fe\({}_{2}\)O\({}_{3}\) & 4.70 & 7.1 \\ MgO & 1.70 & 2.4 \\ K\({}_{2}\)O & 0.28 & 3.4 \\ Na\({}_{2}\)O & 0.31 & 0.4 \\ SO\({}_{3}\) & 3.90 & 0.3 \\ \hline \multicolumn{3}{c}{Physical properties} \\ \hline Specific gravity & 3.10 & 2.8 \\ \hline \end{tabular}
\end{table} 
Table 1: Chemical and physical properties: Composition, OPC, and FA. The GFRP installation uses the wet hand-layup system as per ACI [51]. Short glass fibers (SGF), acquired from Sika Egypt, as shown in Figure 1b, have a length of 6 mm, a specific gravity of 0.91, a diameter of 13 microns, and tensile strength of 480 Mpa, according to the manufacturing sheet. The EP has two components of resin and hardener. The mixing ratio of resin to hardener is 4:1 by weight. The mechanical properties of EP with and without SGF are presented in Table 2. Two percentages of SGF, 0.6% and 1.20%, from the volume of the EP were used. The second bonding material is GPP which includes fly ash (FA) and a mix of sodium silicate (Na\({}_{2}\)SiO\({}_{3}\)) solution with sodium hydroxide (NaOH) solution as an alkaline activator. The chemical composition of FA is illustrated in Table 1. The specific surface area and the specific gravity of FA are 379 m\({}^{2}\)/kg and 2.25, respectively. The utilized sodium hydroxide (NaOH) is available as flakes with a particle size of approximately 3 mm and a specific gravity of 2.13, and a pH of 14. 40 g/mol was utilized as the molar mass. By dissolving sodium hydroxide flakes in water, a sodium hydroxide (NaOH) solution was created. The mass of NaOH solids in a solution disperses according to the solution concentration expressed in terms of the molar. In this research, NaOH solution with 12 M (480 g/L) was used. To provide this molarity, a volume-measured beaker was used. Firstly, NaOH flakes were added, and then water was added until the volume was completed to one liter. After the stirring process was completed, the solution was left to cool down, and then the beaker was refilled to one liter. From the market, a sodium silicate solution in a ready-to-use form was purchased. The chemical formula for the sodium silicate solution is SiO\({}_{2}\) = 29.4%, Na\({}_{2}\)O = 14.7%, and water of approximately 55.9% by mass.