# Environmental Impacts of Cement Production: A Statistical Analysis
## 1 Introduction  
In recent years, the interest for environmental protection has grown faster, becoming an important criterion for public policy in social and political contexts [1, 2]. The most pursued objective is to reduce emissions of greenhouse gases (e.g., carbon dioxide, nitrous oxide and methane), which are responsible for the greenhouse effect [3]. In particular, the cement industry contributes about 5% of global anthropogenic CO\({}_{2}\) emissions excluding land-use change [4, 5], as the production of the binder is a highly energy-intensive and emitting process. Calcination of raw materials for the cement production (e.g., limestone, clay, calcareous marl and other clay-like materials) and burning (fossil) fuels to maintain high temperature in the kiln are the processes with highest environmental impact. The former is a chemical emission, the latter a physical emission. Indeed, raw materials are heated inside large rotating furnaces at 1400 \({}^{\circ}\)C to form a solid substance called clinker [6]. During this process, chemical emissions mainly come from calcium carbonate (CaCO\({}_{3}\)) and magnesium carbonate (MgOCO\({}_{3}\)) calcination according to Equations (1) and (2) [7, 8]:  
\[\text{CaCO}_{3}(\text{s})+\text{heat}\rightarrow\text{CaO}(\text{s})+\text{CO }_{2}(\text{g}) \tag{1}\]  
\[\text{MgO}_{3}(\text{s})+\text{heat}\rightarrow\text{MgO}(\text{s})+\text{CO }_{2}(\text{g}) \tag{2}\]  
Clinker is then ground or milled with gypsum and other constituents (e.g., products, raw materials, additives, recycled waste) to produce cement [9]. According to [9], 5 main types of cement (CEM I toCEM V) and 27 products in the family of common cements are defined. They differ for composition (proportion by mass) of the main constituents, but all contain clinker. Therefore, its production affects the environmental performances of the final product and cannot be overlooked in this study. The chemical process described in Equations (1) and (2) implies more than 60% of total CO\({}_{2}\) emissions due to clinker production, as confirmed by the mass balance published in the last Environmental Product Declaration (EPD) of the Italian cement production [10]. Chemical emissions are not reducible, but physical emissions resulting from fuel combustion for kiln firing can be managed and reduced using alternative/waste fuels [11] and/or by adopting energy-saving technologies [12]. However, these changes in production processes have to turn out in agreement with the required quality of the obtained products, related to construction or industrial uses [13], or with some special performances to obtain [14; 15; 16]. Moreover, in order to reduce the impacts of cement production, in the last decade the content of clinker in cement has decreased [17] using supplementary cementitious materials (e.g., gypsum, ground limestone, coal fly ash or blast furnace slag) [18; 19; 20]. Therefore, the cement industry is making efforts to reduce its environmental impacts in terms of greenhouse gases that reflect on other environmental performances. The standard EN 15804 \"Sustainability of construction works, environmental product declarations, core rules for the product category of construction products\" [21] defines the core rules for the product category of construction Products in order to assess the life cycle impact and develop a Type III environmental declaration (i.e., EPD) for any construction product and construction service [22]. According to [21], different parameters describe the environmental performances of a product, such as environmental impacts, resource use, waste categories, and output flows [23; 24; 25; 26; 27]. In the literature, several studies assessed the impacts of cement production considering its upstream processes (i.e., production of commodities, raw materials, transport to the factory plant, production process) [28]. The obtained results allow the cement industry to identify the best strategies to reduce its environmental impact.