## 4 Discussion  
The Fuzzy-TOPSIS based approach has been implemented to manage the use of siliceous concrete materials for sustainable development. [PERSON] et al. [PERSON] et al. (2018) applied the Analytic Network Process (ANP) as a multi-criteria decision-making method for sustainable material selection for building, considering the holistic impact of materials on the environment through sustainable criteria which are marked as economic, technical, socio-cultural, and environmental factors. The importance of the criteria and sub-criteria in choosing sustainable materials was determined through this model. Whereas, the present study implements the Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) approach, a Multi-Criteria Decision Making (MCDM) technique, for orderly management of siliceous materials based on sustainable criteria, namely, technical, environmental, social and economic aspects and to promote sustainable development. Various sustainable criteria viz. technical, environmental and socio-economical, are considered. It has been observed that, in accomplishing the sustainable goals for siliceous concrete materials, the environmental criteria play a central role, whereas the social criteria play the minor role. It has also been observed that the most effective sustainable indicator for the ranking of siliceous concrete materials is \"concrete material \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Supplementary Material** & **Alternatives** & \(\mathbf{d_{i}^{+}}\) & \(\mathbf{d_{i}^{-}}\) & \(\mathbf{cc_{i}}\) & **Ranking** \\ \hline Limestone & \(A_{1}\) & 15.2620 & 6.3464 & 0.2937 & 9 \\ Blast Furnace Slag & \(A_{2}\) & 13.2325 & 8.6205 & 0.3945 & 3 \\ Metakaolin & \(A_{3}\) & 13.8836 & 7.9110 & 0.3630 & 5 \\ Fly Ash & \(A_{4}\) & 13.3874 & 8.4508 & 0.3870 & 4 \\ Rise Husk Ash & \(A_{5}\) & 15.6305 & 6.0714 & 0.2798 & 10 \\ Silica Fume & \(A_{6}\) & 15.1549 & 6.4536 & 0.2987 & 6 \\ Nano-Cement & \(A_{7}\) & 11.3468 & 10.7590 & 0.4874 & 1 \\ Nano-Particles Supp. Mat. & \(A_{8}\) & 13.2058 & 8.6757 & 0.3965 & 2 \\ Recycled Aggregate & \(A_{9}\) & 15.4692 & 6.0042 & 0.2796 & 11 \\ Waste Glass & \(A_{10}\) & 15.1564 & 6.4067 & 0.2971 & 7 \\ Natural Pozolona & \(A_{11}\) & 15.1606 & 6.4065 & 0.2971 & 8 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The fuzzy positive ideal reference point (FPIRP) and fuzzy negative ideal reference point (FNIRP) distances, closeness coefficients and rank of each sustainable siliceous materials. Figure 2: Ranking of each alternative material based on closeness coefficient. conservation\". It indicates that concrete material conservation is a major issue in sustainable material management and the use of siliceous concrete material should be mandatory in the construction industry for sustainable development. The least effective sustainable indicator observed is the \"enhanced employment\", and siliceous concrete materials application has no major impact on social development. Among the eleven selected siliceous concrete materials, nano-engineered materials, namely, nano-cement and nano-particles of siliceous material should be given top priority in material management for the manufacturing of sustainable concrete product. The siliceous materials come next for sustainable concrete construction. The recycled material to be used as siliceous concrete materials occupies the lowest rank among the sustainable concrete materials. The ranking of the material in descending order of preference to produce sustainable concrete is: Nano-cement \(>\) Nano-particles of siliceous material \(>\) Blast Furnace Slag \(>\) Fly Ash \(>\) Metakaolin \(>\) Silica Fume \(>\) Waste Glass \(>\) Natural Pozolona \(>\) Time Stone \(>\) Rice Husk Ash \(>\) Recycled Aggregate, where '\(>\)' represents preference over other concrete material.