Relative Performance of Limestone, Marble, and Basalt Powders in Replacement of a Recycled Fine Aggregate from Red Mud and Metakaolin-Based Geopolymer Mortar

The current investigation was conducted to reduce the environmental impact of wastes comprising a green, sustainable recycled geopolymer composition (RGC) including granulated-ground-blast-furnace slag (GGBS), metakaolin (MK), red mud (RM) and recycled fine aggregate (RFA). In addition, leftover industrial materials, such as limestone (LS), marble (MR), and basalt (BS) powders, are employed as fillers to replace RFA in various proportions (25, 50, and 75%). Thus, a green RGC consists of wastes. Here, sodium silicate and sodium hydroxide are preferred to prepare a 12 M alkali solution for RGC. Then, physical ultrasound pulse velocity and mechanical compressive and bending strengths are applied to RGC, and the results are evaluated. In addition, to find the best solution for the RGC mixtures, TOPSIS is employed, and the best RGCs are determined for each group, with respect to their physical and mechanical properties. Also, the durability tests are conducted on RGCs determined by TOPSIS. It is found that the best RGC mixture includes 25% RFA with 75% BS.