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Efficient Management of Asbestos Waste Through Utilization as Mineral Additives in Portland Cement Production
This article presents research on the effectiveness of utilizing asbestos waste, particularly chrysotile asbestos, in the production of Portland cement. The study aimed to evaluate the feasibility of transforming asbestos cement (Eternit) through thermal treatment and its enrichment with mineral additives, enabling its integration into the clinker synthesis process. Differences in the physicochemical properties of types of cement produced from conventional raw materials and those manufactured using asbestos waste were analyzed. The research findings indicate that the presence of asbestos in cementitious materials leads to a significant mass loss of 29.4% due to thermal decomposition. Chemical analysis revealed the presence of aluminum oxide (Al2O3) and iron oxide (Fe2O3) at levels of 4.10% and 3.54%, respectively, suggesting the formation of brownmillerite, a phase typical of cement clinker. Furthermore, compressive strength tests on asbestos-modified cements demonstrated comparable mechanical properties to reference cement (CEM I), indicating their potential applicability in construction. This study provides essential insights into the mineralogical composition of asbestos cement, which is crucial for developing effective methods for its safe disposal. It represents a significant step toward sustainable asbestos waste management and the promotion of innovative solutions in the construction industry.
Synthesis and Investigation of the Hydration Degree of CA2 Phase Modified with Boron and Fluorine Compounds
This study investigated the effect of fluoride and boron compound additives on the synthesis and hydration process of calcium aluminate (CA2). The analysis showed that the temperature of the full synthesis of CA2 without mineralizing additives was 1500 °C. However, the addition of fluorine and boron compounds at 1% and 3% significantly reduced the synthesis temperature to a range of 1100–1300 °C. The addition of fluoride compounds did not result in the formation of fluoride compounds from CaO and Al2O3, except for the calcium borate phase (Ca3(BO3)2) under certain conditions. In addition, the cellular parameters of the synthesized calcium aluminate phases were not affected by the use of these additives. Hydration studies showed that fluoride additives accelerate the hydration process, potentially improving mechanical properties, while boron additives slow down the reaction with water. These results highlight the relevance of fluoride and boron additives to the synthesis process and hydration kinetics of calcium aluminate, suggesting the need for further research to optimize their application in practice. TG studies confirmed the presence of convergence with respect to X-ray determinations made. SEM, EDS and elemental concentration maps confirmed the presence of a higher Al/Ca ratio in the samples and also showed the presence of hexagonal and regular hydration products.