The utilization of Linz–Donawitz (LD) slag in cementitious applications has gained traction due to its widespread availability, offering a potential solution to reduce global warming. This study evaluates the impact of particle size fractions on the chemical, mineralogical, and dissolution characteristics of LD slag. Nine particle size fractions were analyzed, revealing significant variations in oxide content based on particle size. While CaO, Fe2 O3, and SiO2 contents remain similar in higher (+500??xm and +1,000??xm) and lower (+3??xm) size fractions, particles between +3??xm to +75??xm exhibit a 1.5% free lime content. Quantification using XRD-based Rietveld refinement indicates LD slag primarily consists of crystalline phases (quartz, calcite, portlandite, brownmillerite, wustite, and belite) alongside an amorphous phase, with amorphous content ranging from 40% to 60% across all sizes. The +3??xm size fraction exhibits the highest belite, brownmillerite, and wustite content, with comparatively lower free lime content than other size fractions. Dissolution analysis in an alkaline environment shows a slightly improved dissolution behavior with decreasing particle size from +150??xm to +3??xm. Calcium exhibits higher initial dissolution rates than iron and silicon within the first three hours, with silicon becoming more prominent after twelve hours. Overall, this study offers a comprehensive analysis of the correlation between particle size and chemical/mineralogical composition, highlighting the potential for converting industrial waste into ecofriendly products.

The increasing importance of biomass-based energy production as a critical component of sustainable energy resources and effective waste management necessitates a comprehensive understanding of the fundamental properties of biomass feedstocks. This review critically evaluates the physicochemical and fuel characteristics of seven widely available biomass sources in India (sugarcane bagasse, sugarcane tops, rice husk, rice straw, maize stalks, maize cobs, and empty palm oil fruit bunches), with a particular focus on the impact of torrefaction. Despite the well-documented benefits of torrefaction in improving biomass properties, limited studies have compared the specific effects of this thermal pretreatment process across diverse biomass sources. This review addresses this gap by critically analyzing the impact of torrefaction on key biomass properties, including hemicellulose, cellulose, lignin, elemental composition (carbon, hydrogen, nitrogen, and sulphur), moisture content, volatile matter, and high heating value, providing a comparative analysis to determine the optimal biomass for energy applications. Moreover, the review critically analyzes the impact of torrefaction on key biomass properties, including hemicellulose, cellulose, lignin, elemental composition (carbon, hydrogen, nitrogen, and sulphur), moisture content, volatile matter, and high heating value. Furthermore, the review synthesizes recent findings to identify optimum torrefaction conditions that enhances the properties of each corresponding biomass. By providing a comprehensive analysis of the complex relationships between biomass characteristics and their practical applications, this review contributes to the advancement of sustainable energy production by optimising biomass-based energy systems and promoting waste-to-energy strategies

The environmental impact of Portland cement production has intensified the search for alternative low-carbon cement. Reactive magnesium oxide cement has emerged as a promising option. The current study investigates the hydration behavior, strength development, and phase evolution of MgO and MgO-RHA blends cured under sealed and carbonation conditions. Two RHA sources with differing amorphous content and particle size were used. A detailed investigation was conducted using various techniques, including calorimetry, TGA, FTIR, XRD, Raman spectroscopy, and SEM. Results showed that higher glassy content and finer particles in RHA enhanced cumulative heat release, hydration product formation, and compressive strength. Carbonation curing further improved strength consistently by promoting the formation of nesquehonite and magnesium silicate hydrate. Quantitative XRD revealed that M-S-H formation was influenced by the consumption of periclase and unreacted glassy phase. Raman and FTIR analyses confirmed significant chemical and structural transformations, including the formation of brucite, nesquehonite, and carbonate phases. The D and G-band features in MgO-RHA samples suggested variations in carbonated products, influenced by processing conditions. Finally, SEM analysis revealed various carbonated products, M-S-H, and a dense microstructure. Overall, the study emphasizes the critical role of RHA properties and curing strategies in optimizing the performance of MgO-RHA systems for sustainable binder applications.

Concrete production is energy-intensive and has an adverse impact on the environment due to the raw materials involved. Currently, India has abundant reserves of fly ash and ground granulated blast furnace slag (GGBS). Despite various applications, fly ash often ends up in landfills. Given its abundance, there is a growing interest in utilising substantial quantities of fly ash in concrete production. In the current study, M30-grade concrete is designed with very high levels of fly ash and GGBS. Additionally, quick lime (QL) is incorporated as a supplementary agent to augment lime content. A total of twenty concrete mixes have been developed with different combinations of fly ash, GGBS, and QL. Results illustrate that the addition of QL does not show overall strength improvement to the GGBS-based mixes, but it impacts on fly ash-based mixes. The targeted design strength is achieved with 70% cement replacement with fly ash and QL. The strength development depends on the pozzolanic reaction initiated and the formation of hydration products in the system. The environmental impact of concrete is assessed by analysing its life cycle assessment using a cradle-to-gate approach. The energy requirement and kg-CO 2 eq. emissions depend on the level of cement replacement. The fly ash-based concrete emits less kg-CO 2 eq. and requires less energy than the GGBS-based mixes. Overall, the designed strength is achieved with 65% fly ash, requiring 59% less energy, reducing 54% CO 2 footprint, 56% GWP 100, 80% HTP inf, 46% ODP inf, and cost by 34% compared to OPC-based concrete.

This study investigates the microstructure, phase formation, and mechanical properties of LC 3 -50 based autoclaved aerated blocks. The microstructure and phase formation is studied using SEM-EDS and X-ray diffraction techniques. The fresh and hardened properties are determined using different methodologies. Three different densities (i.e.500,600,700 kg/m 3 ) are designed by varying the aluminum powder dosage. The compressive strength and thermal conductivity depend on the density of the block. The primary hydration product formed during the autoclave process is katoite, and it is responsible for the strength development in LC 3 -50 based blocks to a certain extent. The autoclave process will help the carbonation of the block altogether, and portlandite is converted to calcite during the autoclave process. Secondary phases like ettringite, monosulfoaluminate and hemicarboaluminate were converted to anhydrite during the autoclave process. Excess lime changes the mechanism of the phase formation, and it initiates the formation of two significant phases: tobermorite and katoite. Significant clinker is present in the unhydrated form.