Investigating the usability of some waste lime sources in gypsum - lime-pozzolan based mortars

In recent years, various mineral additives have been used in the production of building materials. Most of these mineral additives, which can be natural or artificial, consist of industrial by-products (fly ash, silica fumes, blast furnace slag, etc.). Among the reasons for the use of these additives, besides their technological contributions, there are also economic and ecological reasons. As it is known, some reactions called "pozzolanic reactions" occur between mineral additives with pozzolanic properties and lime, and as a result of these reactions, formations similar to the products of hydration reactions between cement and water occur. Thus, pozzolanic reactions contribute to the mechanical properties of the final product. In addition, the use of pozzolanic materials, which are industrial by-products, in building materials contributes to the solution of environmental problems by making use of these waste products. At the same time, since these products, which are waste, have no economic value, they can make the cost of building materials more affordable. Pozzolanic materials are frequently used in concrete and cement-based products but there are many studies in the literature on the use of pozzolanic materials in lime-based mortars. Lime and gypsum, one of the oldest known binders, is widely used in the construction industry today. As it is known, lime is formed by calcining limestone. An unconsciously increasing consumption will cause the depletion of natural resources. At the same time, since the calcination process is a process that requires energy, unconscious consumption also causes energy consumption. Many industrial processes generate wastes containing lime as a by-product. A series of lime-based mortars will be prepared in this project. These lime mortars was developed with pozzolans in order to improve their mechanical properties. Fly ash, rice husk ash and metakaolin, which are known to be highly pozzolanic, were used together with lime mortars. At the same time, in order to protect natural lime resources, various waste lime resources was used instead of lime, and evaluated separately with the mentioned pozzolans. Within the scope of the study, Afşin - Elbistan fly ash, sugar factory waste (filter cake), colemanite waste (triage waste) and ground waste egg shell was used as waste lime source. At the same time, gypsum will be used in the mixtures to adjust the setting time. Two different curing regimes were applied to the produced mortars as steam cure and humid cure. Flow diameter values, compressive and bending strengths, unit weights, ultrasonic pulse velocities, capillary water absorption and atmospheric water absorption values of the produced mortars were examined. At the same time, X-ray diffractometry, Thermogravimetric analyze and Scanning Electron Microscopy Analysis were performed for microstructure investigations. Thus, it is aimed to obtain lime - gypsum - pozzolan mortars with increased environmental and economic aspects and improved mechanical and physical properties. Keywords: Lime, gypsum, pozzolan, waste containing lime