Industrial and municipal waste in solid, liquid and gaseous forms are the main environmental pollutants of our planet. The constant rise in atmospheric temperature caused by them calls into question the survival ability of future generations of people. According to the authors of this study, the only way to overcome this dangerous trend is to develop methods for the disposal of all types of waste as valuable raw materials and to apply them at an industrial level with a remarkably high environmental and economic efficiency.
The results of this experimental study convincingly prove the possibility of environmentally friendly building materials’ producing from such most widely spread industrial waste as iron ore treatment waste (IOT), concrete production and demolition debris (CDD) and lime production wastes (LPW) instead of more costly traditional natural components of building materials - sand, clay, crushed stone, rock gravel and others.
For the Institute of Technological Research (IPT) of Brazil, the world reserve of iron in 2016 was near 170 billion tons; during production of one ton of iron is generated near 400 kg of IOT sludge (i.e., annually about 289 million tons of IOT sludge) with exceptionally low level (5.4%) of utilization (IPT, 2019). The calculations of Freitas, et al (2019) demonstrated even worse results - only 0.003% IOT are reused. Therefore, between the years 2000 and 2017 there were 36 cases of IOT tailings dams’ failures in the world, an average of two per year, which caused significant environmental damage (Wise Uranium (2015). Two major irreparable disasters occurred in 2015 in Brazil (Mariana), in which 50 million cubic meters of IOT leaked and reached the Atlantic Ocean; the second one was in Brumadinho (2020) that poured 13 million cubic meters (Freitas, et al, 2019). One of the best ways to avoid similar harmful damages is to apply IOT as a principal valuable by-product for civil construction material and to decrease its accumulation in the dumps. Galvão et al (2018) offering it as a sustainable reddish paint for construction pigment; for mortars and laying bricks production (Fontes. et al, 2016); for Portland cement clinker (Luo, et al, 2016; Yao, et al, 2020); to improve resistance to sulfates attacks (Xiong, et al, 2017); as replacement for fine aggregate in concrete (Shettima, et al, 2016).
Concrete production and demolition (CDD) debris is a waste of all types of technological processes associated with the production and destruction of building concrete. The amount of its production in different countries is estimated differently and depends mainly on the life standard of the society. For example, in the European Union (2018) it reached 46% in 2018 of the total amount of waste (Akhtar and Sarmah, 2018) and much less in developing countries (Huanga, et al, 2018). Zhang, et al (2017) informed that annual CDD production in China is about 3 billion tons. Typical components in the CW are inert materials, such as concretes with almost 90% of natural rocks, mortars, and ceramics, slate, glass, which have proven to be a substitute for natural aggregates (Fatemi and Imaninasab, 2016). According to Brazilian norm NBR 15116 (2004), at least 90% of CDD mass are fragments of natural rocks.
Therefore, Silva, de Brito and Dhir (2014) studied properties and composition of recycled aggregates from construction and demolition waste suitable for concrete production. Xuan, Sun and Zheng (2018) applied CDD non-structural concrete artifacts and for cement production (Robalo, et al, (2021); in composites with fly ash, dust from cement kilns and gray water (Bassani, 2019).
Large amount of lime production waste (LPW) is formed mainly due to two reasons: when calcining carbonate rocks occurred below 960°C or during long-term storage of lime with access of humid air. Brazilian norms NBR 6453 (2003) allow a maximum of 12% of total CO2 content with chemical impurities like Fe2O3, Al2O3, SiO2. Otherwise, this material is called lime production waste (LPW) and cannot be marketed and used as construction lime.
Usually, LPW is used for sanitary purposes of municipal sewage sludge treatment, to create an alkaline environment for various technological processes, like activator of chemical slag-soil interaction of road base construction in Kazakhstan (Mymrin, et al, 2019). Pedroso (2019) cement-less concrete from three types of industrial wastes: of cellulose production, concrete demolition (CDD) and lime production. LPW can be used in composites with two different types of spent sunflower cooking oils and brick waste powder as pozzolanic addition of new lime mortars (Pahlavan, et al, 2017) or glass mortars (Yang, Poon, Ling, 2019); to produce cementless controlled low-strength material based on waste glass powder (Xiao, et al, 2021); for soil stabilization based on recycled-glass powder waste and dolomitic lime (Baldovino, et al, 2021); for preparation of geopolymer (El-Naggar, et al, 2019); as amendment of municipal sewage sludge with lime and mussel shell (Wang, et al, 2019) or for production of lime-incineration sewage sludge ash pastes (Zhou, et al, 2021); for cementless controlled low-strength material based on waste glass powder (Xiao, et al, 2021). LPW was used also Karanac, et al (2018) fly ash as a low-cost adsorbent of Zn2+, Pb2+, and As+5 ions.
Objectives of the study
A study of the available world scientific research literature, some of them are mentioned above, showed that there is no information on the development of building materials, produced from iron ore treatment waste, concrete production / demolition debris and lime production waste. The production of building materials is the largest consumer of natural resources, a significant part of which can be replaced by industrial and municipal waste with remarkably high environmental and economic efficiency. The recent ecological disasters in brazilian history forced the development of as many compositions of building materials as possible with the largest content of these and other waste. The solution to this problem is the main goal of this study. Elucidation of the physicochemical processes of the developed building materials’ structure formation was an equally important goal since their structures explain all the properties and reliability of materials during their operation.