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 utilization of river sand in the construction industry increases the demand and forms a several environmental impacts by degradation of river beds. It is very crucial to find the alternative materials for the sustainable development. Granite dust, M-sand, and palm oil fuel ash (POFA) are three of the most abundantly produced industrial by-products, yet their potential use as precursors and alternative fine aggregates has not been fully explored. This study comprehensively investigates the effects of incorporating varying proportions (0–50%) of granite dust into M-sand within both heat and ambient-cured alkali-activated binders (AABs) based on sodium (NaOH + Na₂SiO₃) and potassium (KOH + K₂SiO₃). POFA is utilized as a source material, replacing slag at levels of 10%, 20%, and 30% for the optimized granite dust composition. Extensive laboratory tests were performed to evaluate the physio-mechanical and durability performance of the resulting AABs, including compressive strength, water absorption, sorptivity, acid resistance, and microstructural characterization of the POFA-based alkali-activated samples using advanced analytical techniques. The results indicate that, irrespective of curing temperature, M-sand-based AABs exhibited enhanced setting behavior, compressive strength, water absorption, and porosity properties with up to 30% granite dust substitution. This improvement is attributed to the development of C-A-S-H, N-A-S-H, and K-A-S-H gel phases. In POFA-based AABs, the dense packing of POFA resulted in reduced water absorption and sorptivity compared to control specimens. Overall, the findings suggest that POFA, as a pozzolanic material, significantly improved the properties of granite dust-based AABs, offering a sustainable solution for mitigating the environmental impact and disposal challenges of industrial waste.

The rapid growth of urbanization and the construction industry has led to increased consumption of natural resources, resulting in significant environmental impacts. This study explores the use of three locally available waste materials to develop sodium- and potassium-based alkali-activated binders. Granite dust was employed as an alternative to river sand, with replacement levels ranging from 0 to 50%, and optimized for performance. Additionally, palm oil fuel ash (POFA) was utilized as a source material, replacing slag at levels of 10% to 30% in a control mix, activated using NaOH & Na₂SiO₃ and KOH & K₂SiO₃ under both heat curing at 65 °C and ambient curing conditions. The mechanical and durability properties like compressive strength, water absorption, sorptivity and resistance to acids with influence of the activator, and microstructural characteristics of the binders were thoroughly analyzed. The temperatures effects of specimens were clearly analyzed and the heat cured specimens gives the 25% of lesser strength than the ambient cured AAB irrespective of activator. In both sodium and potassium based alkali activated binders. K-Nearest Neighbors and artificial neural networks were used to forecast the alkali-activated mortar’s compressive strength. Metrics used for performance evaluation, such as the coefficient of determination R2 and RMSE, showed that the ANN model produced better predictions. For sodium-based activators, ANN produced an RMSE of 0.174 and an R2 value of 0.96 under ambient curing conditions, while KNN produced an RMSE of 0.154 and an R2 value of 0.158. The findings highlight the potential use of waste materials, such as POFA, granite dust and slag in the creation of eco-friendly and high-performance alkali-activated binders.

The increased use of sugarcane bagasse in electricity production has led to a significant rise in the dumping of sugarcane bagasse ash (SCBA). To study the efficiency of SCBA as a supplementary material in the production of alkali-activated binders (AABs), which consist of quarry dust and crushed sand as fine aggregates, the present study investigates the influence of different activators, namely NaOH-Na2SiO3 and KOH-K2SiO3, and the effect of curing type (ambient and heat curing) on the mechanical and durability properties of quarry dust-SCBA incorporated AAB. Various tests, including compressive strength, water absorption, sorptivity, and sulphate resistance, along with X-ray diffraction and scanning electron microscopy were conducted for AAB characterization. The results revealed that the addition of 20% quarry dust as an alternative to crushed sand in AAB is found to be optimum. The ambient-cured SCBA-blended AAB specimens demonstrated superior performance compared to their heat-cured counterparts. The Na-based SCBA blended AABs outperformed K-based AABs in resisting compressive strength reduction. The compressive strength of 28 days ambient cured Na-based and K-based AABs were found to be 47.8 and 32.4 MPa, respectively. Microstructural analysis revealed that the main hydration products in Na-based AAB are C-A-S-H, C-S-H, and N-A-S-H, while in K-based AAB, the main hydration products were found to be C-A-S-H, C-S-H, and K-A-S-H, respectively. The AAB mixtures consisting 10% SCBA found with superior performance compared to other SCBA blended AABs. However, excessive SCBA usage weakened the microstructure in both Na-based and K-based AABs. The findings demonstrate the potential for utilizing waste materials, such as SCBA and quarry dust, in the development of eco-friendly and high-performance alkali-activated binders, contributing to the reduction of environmental impact caused by the construction industry.

Natural river sand is preferred as fine aggregate. A large percentage of concrete comprises fine aggregates and hence river sand is over-mined due to the higher demand in the construction sector. Mining of natural river sand affects river banks and is banned in many countries. Earlier studies suggested recycled aggregates as an alternative to river sand. Although studies on the use of recycled fine aggregates have been reported, a systematic review on the comparison of recycled aggregates with other alternative fine aggregates is highly limited. Hence, the present review comprehensively compares the performance of recycled fine aggregates concretes with other alternative fine aggregates such as granite dust, crushed rock, ceramic waste, recycled glass aggregates, recycled brick aggregates, recycled plastic aggregates, and recycled rubber aggregates. Fresh, mechanical, durability properties such as compressive strength, workability, modulus of elasticity, split tensile strength, flexural strength, carbonation, chloride ion penetration, water absorption, sorptivity, permeability, abrasion, ultrasonic pulse velocity, and shrinkage of various alternative fine aggregate used concrete are meticulously compared. The water absorption for recycled concrete fine aggregate used concrete is found to be within the permissible limit for replacement levels of river sand in-between 15%-45%. Research studies also suggested better sorptivity values for recycled concrete fine aggregate used concrete for replacement levels of fine aggregate between 5% and 25%

The construction sector across the world involves constructing huge buildings, which usually consumes enormous energy, causing an incredibly damaging effect on the environment in terms of raw material usage, greenhouse gases (GHGs) emitted, and waste generated in huge quantities, which has drawn much attention from conservationists. Though several preventive measures have been developed to reduce the impact of construction, they are often ignored or mismanaged. Thus, things must be examined in detail with appropriate environmental tools to provide a clear view of the emission released into the environment and mitigate the problem from a broader perspective. Life cycle assessment (LCA) is one tool used for quantifying the emissions into the environment and economic impacts of the chosen product/process. As a result, this study investigates the effects of the precast structural elements for building and their carbon footprint at the different construction phases based on the LCA methodology. The construction phases include (a) the preoperational phase/building construction, (b) the operation phase, and (c) the postoperational phase/building demolition and inventory data are collected from the selected building. The results show that the precast structure's energy (23.33 kW · h/m2) was less compared with reviewed case studies. The global warming potential (GWP) of the present study, 16.55 kg CO2 eq/m2, was the least among all the studies. The life cycle cost (LCC) analysis of buildings was performed, and the LCC of precast structures was 4.78% less than the conventional construction. The study evaluates and compares each phase's emissions and identifies specific hotspots for emissions into the environment. Finally, the authors believe that the study provides valuable insights into the potential environmental impacts for the relevant stakeholders and experts.

Disposal of agricultural waste ashes is significantly increased worldwide due to the rapid implementation of biomass based power plants and leads to severe pollution. Instead of disposal, agro-waste ashes can be efficiently used as an alternative material to conventional cement. However, the reuse of locally available agricultural waste ashes is highly limited in the construction sector because of inadequate understating of their performance in concrete. Hence, a comprehensive review on the performance of two widely available agro-waste ashes, palm oil fuel ash and rice husk ash in concrete is attempted. Physical, chemical, microstructural, and pozzolanic characteristics of palm oil fuel ash and rice husk ash are systematically reviewed. Besides, fresh, mechanical and durability properties of the palm oil fuel ash blended concrete is critically compared with rice husk ash blended concrete. From the literature, it was observed that the inclusion of rice husk ash reduces the workability of concrete significantly, whereas the increase in the workability is reported for the palm oil fuel ash blended concrete. The optimal calcination temperature for palm oil fuel ash and rice husk ash has been reported to be 600-700 °C. Higher silica content is observed in rice husk ash compared to palm oil fuel ash and causes enhanced reactivity. An optimum replacement level of 10–20% is recommended for both rice husk ash and palm oil fuel ash incorporated concretes. Superior performance against chloride ion penetration, acid and sulphate attack is observed for palm oil fuel ash, and rice husk ash blended concretes compared with conventional concrete.

Palm oil biomass based power generation is increased in recent times and it leads to the generation of massive amounts of palm oil fuel ash. Due to the challenges associated with the disposal of palm oil fuel ash, earlier studies focused on the reuse of palm oil fuel ash in a variety of applications. However, a comprehensive review on the reuse of palm oil fuel ash is highly limited. Hence, the present review aims to comprehend the potential use of palm oil fuel ash as a pozzolan in concrete, soil stabilisation, and as an adsorbent in waste water treatment. The addition of palm oil fuel ash as pozzolan up to 20% improved the mechanical and durability properties of the blended concrete. Besides, treatment of expansive soil using palm oil fuel ash enhanced its engineering properties. Moreover, the removal efficiencies of Arsenic(V), Lead(II), Cadmium(II), and Chromium(VI) are 50.2%, 90.27%, 68.46%, and 83.59% with the addition of palm oil fuel ash as adsorbent. However, as compared to raw palm oil fuel ash, the treated palm oil fuel ash exhibited superior performance in concrete and soil stabilisation.

This paper presents the recent research progress on the response of concrete exposed to fire or high temperatures. The main highlight of this review paper is a compilation of previously reported data regarding the variations in mechanical properties and microstructure properties of concrete when exposed to high temperatures. The concrete structures get deteriorated at the macro- and microscopic levels due to high-temperature exposure. The macro-level damages can be measured with degradation in mechanical properties such as the reduction in compressive strength, weight loss, changes in elastic properties, reduction of bond strength in reinforced concrete, etc. The macro-cracks on the surface of concrete causes spalling which can be observed after exposing the concrete samples to more than 300 ℃. The compressive strength of the concrete reduces slightly till 400 ℃, and when the temperature increased to 600 ℃, there was an exponential reduction in the compressive strength of concrete. Another important parameter is bond strength degradation, which plays a crucial role in durability issues. To understand the deterioration phenomenon and changes in mechanical properties, the changes at the level of the microstructure of concrete need to be understood. Dehydration of products causes deterioration of mechanical properties and weight loss of concrete when exposed to high temperatures. At different temperatures, the microstructure changes and the response of hydration products such as calcium hydroxide (CH), CSH gel, unhydrated cement and capillary water reported by previous researchers are compiled and discussed.

River sand is commonly used as a fine aggregate in concrete. Due to the restriction for the use of river sand in several parts of the world to protect river beds, the demand for alternative fine aggregates is significantly increased in the construction sector. On the other hand, the disposal of industrial by-products is a major concern because of stringent environmental regulations. Use of industrial by-products as an alternative fine aggregate in the concrete is a sustainable common solution to the excessive river mining and disposal of industrial by-products. Although earlier studies on alternative fine aggregates are available, a comprehensive review with a consideration of several industrial by-products is highly limited. Therefore, the potential reuse of fifteen industrial by-products as fine aggregate is presented in this review. Influence of characteristics of alternative fine aggregates on properties of concrete such as workability, compressive strength, water absorption, carbonation, abrasion resistance, chloride permeability, sorptivity, ultrasonic pulse velocity, and drying shrinkage are critically reviewed and compared. From the detailed review, the optimum replacement level of 20% is witnessed for steel slag, copper slag and granite dust aggregates whereas 40% is the optimum replacement level for bottom ash and crushed rock aggregates. High water absorption of the alternative fine aggregates causes a significant decrease in the workability. Increase in the carbonation depth is observed for all alternative fine aggregates used concretes. Higher sorptivity is found for the concretes comprising alternative fine aggregates except for recycled concrete and recycled glass aggregates. The inclusion of recycled ceramic and copper slag aggregates improved abrasion resistance of concrete.