**4. Discussions and Future Perspectives**

This study provided a statistical overview and mapping of various aspects of the literature on RHA concrete. Previous manual review studies have limitations in terms of their ability to comprehensively and accurately connect diverse sections of the literature. This study identified sources (journals) that published most articles, most commonly employed keywords in the published papers, articles and authors having most citations, and countries actively involved in the research of RHA concrete. The analysis of keywords identified that RHA had been examined for its possible applications as SCM in conventional concrete, self-compacting concrete, and high-performance concrete due to the presence of high silica content in its chemical composition [114–118]. In addition, the use of RHA is also researched for manufacturing geopolymer concrete [119–121]. RHA provides several advantages when used in concrete. RHA has been investigated for prospective use as a cement or fine aggregate substitute in concrete. The issues associated with manufacturing and the use of cement might be decreased [122]. Also, because natural aggregate extraction consumes a significant amount of energy and results in higher CO2 emissions [123]. As a consequence, concerns regarding natural resource depletion may be alleviated. Thus, the incorporation of RHA into concrete minimizes the need for cement and fine aggregate, resulting in a more environmentally friendly construction material [124]. By incorporating RHA into construction materials, waste management difficulties can be solved [73]. In addition, the most active and contributing countries in terms of publications were identified from the literature and their connections based on citations. The statistical and graphical representations of the contributing states will assist developing scholars in creating scientific partnerships, establishing joint ventures, and exchanging novel approaches and ideas. Researchers from countries interested in advancing RHA concrete research can collaborate with professionals in the area and benefit from their knowledge.

Most of the RHA applications stated above are still in their development, and more indepth analyses are necessary before broadening their applicability [71]. Furthermore, in the present practice, the utilization of RHA concrete in full-scale reinforced concrete structures under service and high loading circumstances has not been examined. Additionally, there are currently no clear standards for the preparation, processing, and use of RHA on a larger scale. In the available literature, researchers have solely relied on their intuition to determine the optimal degree of cement and fine aggregate replacement using RHA [105]. Additionally, previous work has not explored the compatibility and long-term durability of RHA concrete. Steel reinforcement corrosion in RHA-blended concrete must be researched in water, chloride, sulphate, and acidic environments over an extended period of time. Also, because information on the life cycle evaluation of RHA concrete is limited and needs to be thoroughly examined. To enhance the strength of concrete, alternative and supplemental additives such as nano-silica and fibers can be added to RHA concrete. Additionally, the high concentration and coarser character of RHA allow for the formation of a porous and less dense matrix of the concrete. Nonetheless, the addition of nano-clay, short fibers, and nano-silica to concrete has demonstrated the ability to increase its density, shock resistance, and tensile stress resistance. As a result, these additives combined with RHA-blended concrete may provide another sustainable material for future construction.

#### **5. Conclusions**

The objective of this study was to conduct a scientometric analysis of the available literature on rice husk ash (RHA) concrete in order to assess various measures. The Scopus database was queried for 917 relevant papers, and the results were analyzed using the VOSviewer program. The following findings were drawn from this study:

• An analysis of publication sources containing documents on RHA concrete research exposed that the topmost three sources are "Construction and building materials", "IOP conference series: materials science and engineering", and "Materials today: proceedings", with 110, 48, and 45 papers, respectively, Also, the leading three publication sources in terms of overall citations are "Construction and building materials" with 6797, "Cement and concrete composites" with 2268, and "Journal of cleaner production" with 1579.


**Supplementary Materials:** The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/ma15103431/s1. Table S1: Data retrieved from the Scopus database and used for the analysis.

**Author Contributions:** M.N.A.: conceptualization, funding acquisition, resources, project administration, supervision, writing, reviewing, and editing; W.A.: conceptualization, data curation, software, methodology, investigation, validation, writing—original draft; K.K.: methodology, investigation, writing, reviewing, and editing; M.M.S.: resources, visualization, writing, reviewing, and editing. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the Deanship of Scientific Research, Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Saudi Arabia [Project No. GRANT461]. The APC was funded by the same "Project No. GRANT461".

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data used in this research have been properly cited and reported in the main text.

**Acknowledgments:** The authors acknowledge the support from the Deanship of Scientific Research, Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Saudi Arabia [Project No. GRANT461]. The authors extend their appreciation for the financial support that has made this study possible.

**Conflicts of Interest:** The authors declare no conflict of interest.
