Lime-based mortars, frequently used in historic structures, are classified as hydraulic and non-hydraulic according to how they gain strength. In the past, various methods were used to improve the strength and durability properties of lime-based hydraulic mortars such as Khorasan mortar. Today, in studies carried out to increase the strength of lime-based mortars, the effects of binders, aggregates, and additives, which are the basic components of the mortar, are examined. In this study, the mechanical properties of Khorasan mortar mixtures, which are frequently used in the restoration of historical structures, were examined under the influence of different parameters. In particular, the effects of variables such as aggregate type and ratio (river sand and crushed brick), binder type and ratio (natural hydraulic lime, metakaolin, and blast furnace slag), and water/total dry material ratio on the strength of mortars were investigated experimentally. In the experimental study, two different aggregate types (river sand and crushed brick) were used in 1/3 and 1/2 ratios, and three different binders (natural hydraulic lime, metakaolin, and blast furnace slag) were used in different ratios. The water-to-total-dry-material ratios were set at 0.2 and 0.25. Standard test samples were then created from the prepared mortar mixtures, and their flexural and compressive strengths were assessed at 28 and 56 days. A statistical analysis of the experimental data was conducted using the Taguchi method, allowing for a detailed examination of how the different parameters influenced the strength of the mortars. Through this analysis, the optimal mixture ratios that maximized mortar strength were successfully identified.

This study investigated the effects of waste steel fiber and high-volume blast furnace slag (BFS) substitution on the mechanical and physical properties of three-dimensional printable concrete (3DPC) to improve its environmental performance. BFS was substituted for cement at 0%, 25%, 50%, and 75% by volume. Waste steel fibers were added to the mixtures at three lengths (5, 10, and 15 mm) and two volumetric ratios (0.5% and 1.0%). Twenty-eight mixtures were optimized based on extrudability, buildability, and shape stability criteria. Parameters such as compressive and flexural strength, surface moisture content, and drying shrinkage were evaluated. The results showed that using up to 0.5% waste steel fibers increased compressive strength by up to 23%, but decreased it to a level of 1%. Fiber reinforcement improved the flexural strength of all blends by up to 53% at both ages, regardless of fiber ratio or length. Increasing the BFS substitution rate generally increased surface moisture however, this value decreased in mixtures containing 75% BFS and silica fume. Furthermore, using steel fibers and in-creasing fiber length significantly improved the drying shrinkage performance of the mixtures.