The Mechanical Strength of Ecological Cement Mortars Based on Fly Ash from the Combustion of Municipal Waste and Cement Klin Dust  
[PERSON]  
1 Faculty of Civil Engineering, Czechowna University of Technology, 42-201 Czestochowa, Poland; alina. it is necessary to limit the chlorine and alkali content in the process [3]. The chemical composition and properties of CKD and CBPD can vary depending on the raw materials, fuel, and production technology used. CKD is typically less contaminated, while CBPD is characterized by higher contents of chlorides, potassium oxide, and sulfur trioxide, limiting its usability in other industrial sectors. The amount of by-products such as CKD and CBPD can range from 0% to 25% of the clinker mass, depending on the production technology and raw materials used [4]. In large cement plants, daily CBPD production can reach up to 1000 tons [5]. Waste dust from cement production are classified under waste category 10 13 80. Cement kiln dust (CKD) is finding increasingly diverse applications in various industrial fields, helping to mitigate its negative environmental impact. Cement kiln dust (CKD) has been widely acknowledged as a cost-effective material for soil stabilization in various studies. For instance, [PERSON] et al. examined its role in stabilizing and solidifying polluted soils [6], while [PERSON] et al. explored its application in inactivating heavy metals present in contaminated soils [7]. [PERSON] et al. highlighted its effectiveness in improving the engineering properties of soil [8], and [PERSON] and Salem applied CKD for the stabilization of dune sands [9]. Similarly, [PERSON] et al. assessed its impact on aggregate stabilization [10], and [PERSON] et al. investigated its potential in optimizing the plasticity of tropical soils [11]. Furthermore, [PERSON] et al. utilized CKD in the production of building materials and road paving [12], while [PERSON] et al. focused on its capacity to enhance the stiffness and strength of aggregates [13]. [PERSON] and [PERSON] demonstrated its use in improving sub-grade materials [14], and [PERSON] et al. emphasized its ability to increase soil stiffness [15]. Finally, [PERSON] et al. highlighted CKD's role in soil treatment [16]. These studies collectively emphasize CKD's versatility and wide-ranging applications in soil and aggregate stabilization. CKD has been successfully used as a replacement for cement in various proportions (5-50%) in applications such as self-consolidating concrete [17], concrete paving blocks [18], lightweight concrete [19], concrete and mortar [20; 21], and concrete production [22; 23; 24]. Due to its properties, CKD helps reduce carbon dioxide emissions associated with cement production, making it a more environmentally friendly solution. Additionally, its application can lower production costs in the construction industry, especially in large-scale projects. In the ceramic and brick industry, CKD also finds extensive use as a cementitious material in various proportions (2-50%). It has been used for producing wollastonite ceramics [25], red clay bricks [26], brick production [27], and pressed building bricks [28]. CKD, with its binding properties, enhances the durability and strength of finished products, making it an attractive raw material for the ceramic sector. Furthermore, its usage can contribute to the reduction in industrial waste, supporting circular economy principles. Equally important is the multi-criteria assessment of the efficiency of post-process waste utilization [29]. In the context of a circular economy, increasing attention is being given to the potential use of another material--waste fly ash (MSWI-FA) generated during the incineration of municipal waste. Interest in the thermal treatment of waste is growing as the volume of municipal waste continues to increase. In 2022, the average per capita generation of municipal waste in the European Union was 513 kg, of which 61.1% was recovered, including 20.2% that underwent thermal treatment with energy recovery.