## 7 Reinforced GPC  
The reinforced GPC is an important structural component to be studied and analyzed for its use in the construction industry. Different experimental investigations determined that the reinforced GPC, when compared to reinforced OPC concrete, possesses better mechanical and durable properties [7; 171; 172]. In reinforced GPC, the mechanical and structural properties depend significantly on the bond strength between the concrete and reinforcement because it is an essential property in the design of structural elements. From previous studies [172; 173], it was found that the determination of bond strength of reinforced GPC mainly depends on factors like concrete strength, bar diameter, cover/bar diameter ratio, splice length, embedded length, and steel fiber reinforcement. Furthermore, other characteristics like type of binder, activator/binder ratio, silicate/hydroxide ratio, water/binder ratio, molarity and concentration of activator, and the curing conditions are considered for determining the bond strength [174; 175; 176]. [PERSON] and [PERSON] [174] reported that GPC possesses better performance than OPC concrete, with a 10% rise in bond strength of GPC. It was concluded that the bond strength of FA-based GPC depends on the bar type (smooth or ribbed) and curing conditions (time and temperature). [PERSON] et al. [177] compared bond strength of reinforced GPC beams with ACI 318-02 and AS 3600 codes. It was reported that the experimental values of ratios are comparable with modeled values. [PERSON] et al. [177] proposed the best fit experimental values of bond strength from Equations (7) and (8) proposed by [PERSON] et al. [178]. \[\sigma=f_{\mathrm{c}}\left[2.07+0.2\times(c/\rho)+4.15\times(\varphi/l_{ \mathrm{d}})\right] \tag{7}\]  
Figure 33: Effect on (**a**) setting time with addition of OPC; (**b**) compressive strength with addition of OPC, modified from [53], Elsevier, 2015. \[\sigma=2.12\times(f_{c})^{0.5} \tag{8}\]  
where,  
\(\sigma=\text{bond strength of GPC}\),  
\(f_{c}=\text{compressive strength of GPC}\),  
\(c=\text{concrete cover}\),  
\(\varphi=\text{bar diameter}\),  
\(l_{d}=\text{developmental length}\). The research trend of reinforced GPC has been practically applied to structural elements like beams, columns, slabs, and walls. Several researchers [179; 180] have found that reinforced GPC beams showed similar mechanical performance when compared to reinforced OPC concrete. It has also been reported that there is no disadvantageous effect of using reinforced GPC as the structural member in the construction industry [173]. The performance of reinforced GPC beam is considerably enhanced by the incorporation of steel fibers [181]. [PERSON] et al. [177] analyzed the performance of bonding of lap-splices and shear behavior of GPC. It was found that the techniques used to predict the shear behavior of conventional OPC concrete can be applied to reinforced GPC. Furthermore, the code provisions and different analytical models applied for calculation and prediction of normal OPC concrete can be sued for reinforced GPC beams. Likewise, the code provisions of AS 3600 for determining the flexural behavior of OPC beams could be used for GPC beams [179]. Nonetheless, more research efforts are required to develop more desirable, realistic, and cost-effective design codes [172]. It has been reported that the load deflection, crack patterns, crack width, flexural stiffness, ultimate load, and failure mode of the reinforced GPC beams are similar to the OPC concrete beams [182; 183]. [PERSON] et al. [182] reported that the total number of flexural cracks and their developed spacing was found the same for both types of beams. Likewise, the ultimate load and mid-span deflection of both reinforced GPC and OPC concrete was reported. It was found that the mechanical properties of reinforced GPC are comparable with that of OPC concrete [184]. In contrast, [PERSON] et al. [185] reported brittle failure of GPC during the crushing test when compared to OPC concrete.