การใช้ตะกรันเหล็กแทนที่ทรายและซีเมนต์ในมอร์ตาร์ / ฉัตรชัย อารมย์ดี = Utilization of stell slag as sand and cement replacement in mortar / Chatchai Aromdee
In this research, steel slag as a by-product from metallurgical processes was used as a pozzolan material in cement mortar. Pozzolanic reaction and cement mortar properties were investigated. The pozzolanic reaction was studied by varying the ratio of hydrated lime Ca (OH)₂ to steel slag at 1:1 1:2 and 1:3. Phase microstructure and thermal properties of the pozzolan products were analyzed by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Differential Thermal Analysis (DTA) techniques, respectively. Cement mortar properties were investigated. Mixtures of steel slag, sand and Portland cement were prepared by replacing the cement with the amount of steel slag at 10, 20, 30 and 40 wt%, and replacing the amount of sand by steel slag as 10, 20, 40, 60, 80 and 100 wt%. Setting time and flow ability of the mixture were measured by Vicat apparatus and slump test, respectively. The mixture was cast in a steel mold of 5 x 5 x 5 cm³ and demolded at 24 h, then kept in water for 3, 7 and 28 days. Microstructure and mineral phase of the hardened mortar products were analyzed by Scanning Electron Microscope (SEM) and X-ray diffractometer (XRD), respectively. It was found that partly replacing of Portland cement and sand by steel slag in the mix of Portland cement mortar would enhance calsium silicate hydrate phase and strength of the specimens. The highest compressive strength of the cement mortar with 20 wt% and 40 wt% steel slag substituted by Portland cement and sand at 28 days was 41.17 and 44.66 MPa, respectively.
