The Effect of Biological Corrosion on the Hydration Processes of Synthetic Tricalcium Aluminate (C3A)

Abstract

This paper presents a study related to the biological degradation of a tricalcium aluminate (C3A) phase treated with reactive media from the agricultural industry. During one month of setting and hardening, synthetic C3A was subjected to corrosion in corn silage, pig slurry and chicken manure. The hardening process of the C3A phase in water was used as a reference sample. The phase composition and microstructure of the hydrating tricalcium aluminate slurries were characterised by X-ray diffraction (XRD), thermal analysis (DTA/TG/DTG/EGA), scanning microscopy (SEM, EDS) and infrared spectroscopy (FT-IR). In the samples studied, it was observed that the qualitative and quantitative phase composition of the synthetic tricalcium aluminate preparations changed depending on the corrosion exposure conditions. The main crystalline phases formed by the hydration of the examined samples in water as well as in corrosive media were the catoite (Ca3Al2(OH)12) and hydrocalumite (Ca2Al(OH)7·3H2O) phases. Detailed analysis showed the occurrence of secondary crystallisation in hydrating samples and the phases were mainly calcium carbonates (CaCO3) with different crystallite sizes. In the phase composition of the C3A pastes, varying amounts of aluminium hydroxides (Al(OH)3) were also present. The crystalline phases formed as a result of secondary crystallisation represented biological corrosion products, probably resulting from the reaction of hydrates with secondary products resulting from the metabolic processes of anaerobic bacterial respiration (from living matter) associated with the presence of bacteria in the reaction medium. The results obtained contribute towards the development of fast-acting and bio-corrosion-resistant special cements for use in bioenergetics.

From Waste to Renewables: Challenges and Opportunities in Recycling Glass Fibre Composite Products from Wind Turbine Blades for Sustainable Cement Production

“…Glass-fibre-reinforced polymer (GFRP) is a type of composite material made from resins (such as epoxy resin, butyl resin), glass fibres, and auxiliary materials such as calcium carbonate, magnesium carbonate, or talc [1]. The physicochemical properties obtained from the combination of these components, including high mechanical strength, ease of shaping, and excellent resistance to chemical and biological corrosion [49][50][51], have made this composite an indispensable material in the production of wind turbine blades, storage tanks, ship hulls, and other laminates of this kind. It is estimated that the global production of industries producing such materials exceeds several million tons annually [75].…”

“…Further information regarding the durability of recovered fibres in the alkaline environments of cementitious pastes is scarce [50,51]. Hence, there is a need for a systematic assessment of the impact of fibre content, dimensions, and chemical composition on the mechanical properties and microstructure of cementitious materials.…”

“…Minor components-specifically selected inorganic materials, the proportion of which does not exceed 5% of the total composition; • Additives-used to improve manufacturing or cement properties. The total amount of additives should not exceed 1% [50,51]. Aluminate cement is a rapidly hardening, hydraulic binding agent obtained by grinding aluminate clinker, obtained by melting or sintering a properly prepared raw material mixture.…”