## 10 Conclusions and Recommendations  
This review article covered the detailed discussion of GPC based on past research and investigations. The main conclusions are as follows:  
* GPC can be recognized as an eco-friendly construction material with better mechanical and durable properties. It is considered to be an appropriate replacement of OPC concrete, which would be possible with an efficient supply of agricultural and industrial waste products.
* Researchers assessed the performance of common aluminosilicates like FA, GGBFS, PFOA, MK, HCWA, silica fume, and RHA or their combinations. However, most of the research was carried out on FA-based geopolymer mortar and concrete since it gave the better mechanical properties compared to other aluminosilicates-based geopolymers due to better physical and chemical characteristics. The most widely used activators in GPC are NaOH and Na\({}_{2}\)SiO\({}_{3}\) or their combination. Several factors such as the concentration, amount, molarity, and reactivity play a vital role in the development of the geopolymerization reaction. In order to achieve better mechanical and durability properties, it is essential to find the optimum activator dosage in the geopolymer blend. Moreover, it was found that the soluble silicates exhibit a fast geopolymerization reaction compared to activators containing hydroxides.
* GPC mechanical, durable, and microstructural properties are further dependent on mix design proportion. While determining the mix design, all factors that are responsible to develop better mechanical properties should be considered like activator to binder ratio, silicates to hydroxide  
Figure 40: Effect of graphene amount on bending strength [235].  
ratio, binder content, activator concentration and molarity, aggregate type and grading, dosage of superplasticizer, water to binder and binder to sand ratio.
* Inclusion of OPC in GPC creates both geopolymerization and C-S-H products that make a compact and dense microstructure. Hence, compressive strength, durability, and microstructural behavior improved along with the reduction in shrinkage, porosity, and water absorption.
* Previous investigations were carried out to evaluate the mechanical properties and durability characteristics based on different factors like NaOH/Na\({}_{2}\)SiO\({}_{3}\) ratio, NaOH/slag ratio, activator/binder ratio, the combination of different activators, curing conditions, curing temperature, curing duration, elevated temperature, molarity of activators, different binders ratio, aggregate type, the addition of nanoparticles, reinforcement ratio, and effect of adding different additives, nanoparticles, recycled aggregate, and steel fibers to find their optimum ratios and amounts.
* Recent advances in GPC such as 3D printing and fiber-based GPC require further in-depth investigations. GWP calculation and LCA techniques provide the way to analyze the sustainable growths. However, further investigations based on different types of aluminosilicates and activators are required.
* Experimental investigations are recommended on standard mix design procedure, newly compatible aluminosilicates and activators, microstructure, brittle behavior, efflorescence and shrinkage phenomenon, cost-effectiveness, practicality of easily handled and field-applicable strength compatible GPC to be used in the construction industry.  
[PERSON], [PERSON] and [PERSON] conceived and designed the idea; [PERSON] and [PERSON] analyzed the data; [PERSON] contributed reagents/materials/analysis tools; [PERSON], [PERSON], [PERSON], and [PERSON] wrote the original draft of paper, [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] revised the draft of paper. All authors have read and agreed to the published version of the manuscript.  
This research was supported by Nazarbayev University Faculty development competitive research grants numbers 090118 FD5316 and SEDS2021006.  
The authors are thankful to the editor and reviewers who provide valuable suggestion to improve this manuscript.  
The authors declare no conflict of interest.