Journal Articles
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Item A comprehensive review towards sustainable approaches on the processing and treatment of construction and demolition waste(Elsevier Ltd, 2023) Trivedi, S.; Snehal, K.; Das, B.B.; Barbhuiya, S.A massive boom in global construction has led to an enormous generation of construction and demolition (C&D) waste. C&D waste is the largest stream of waste, which needs to be treated and utilized efficiently for achieving sustainable goals. Multiple economical and valuable materials are embedded in C&D waste, most of these can be reused as construction materials. Ideally, these wastes are processed or treated near the demolition sites to ensure a constant supply of raw materials such as recycled aggregates for its use in the construction of roads, buildings, and urban landscapes. Several challenges are posed in the processing and treatment of C&D waste as a result of variable material properties as well as its bulky nature. From this point of view, this article presents a structured, comprehensive review of the existing literature on various tools and techniques for procuring recycled aggregates (RA) from C&D leftovers. The latest processing technologies, and subsequent treatment processes for recycled aggregates to make it suitable for further use in concrete is discussed and critically analyzed. Also, diverse approaches for treating the RA are evaluated critically with prime focus on removal of adhered mortar fractions and surface coating techniques. In addition, the modified mixing approach and its implementation in mix design for RA based concrete is emphasized. This article also covers the studies on recycled aggregate concrete at microstructural level, which include characterization techniques such as SEM-EDAX, XRD, FTIR and TGA. Emphasis is also given to embrace the deficiencies associated with RA concrete and improvement techniques for its inclusion in construction works. On the basis of the extensive review, it is understood that subjected to processing of the C&D debris, it yields useful recycled aggregates that can be incorporated into concrete up to an optimum percentage between 15 and 20%. Further, there is a requirement for specified pre-treatment methods that enhances the physio-chemical properties. Also, there is a necessity for the assimilation of mineral admixtures of micron, sub-micron to nano size for overcoming the shortcomings of recycled aggregates for the production of sustainable and high-performance concrete. © 2023 Elsevier LtdItem Valorization of Incinerated Biomedical Waste Ash in Cementitious System: A Comprehensive Review(Springer Science and Business Media Deutschland GmbH, 2025) Joshi, S.; Snehal, K.; Das, B.B.; Barbhuiya, S.Disposing of incinerated biomedical waste ash (IBWA) contaminated with heavy metals (e.g., Cr, Zn, Pb) poses significant environmental and public health concerns, necessitating innovative and sustainable management strategies. Cement-based solidification emerges as a promising approach to repurpose IBWA by effectively immobilizing heavy metals and mitigating their ecological footprint. However, broader industrial and societal acceptance of IBWA as a substitute for cement and sand remains constrained owing to limited quantification of IBWA availability and safety concerns. In this perspective, the current paper presents a global database on IBWA availability and maps the geographic distribution of biomedical waste incinerators in India. It also comprehensively reviews IBWA’s potential in mortar/concrete, focusing on its physico-chemical, leachability, hydration, mechanical, durability, and microstructural properties. The study further highlights the importance of a cradle-to-gate and gate-to-gate Life Cycle Assessment (LCA) to holistically assess the environmental performance of IBWA-incorporated mortar systems, promoting circular economy principles and resource efficiency in the construction sector. IBWA, with its high SiO₂ and CaO content (> 50%), exhibits latent hydraulic properties suitable for construction applications. The porous cellular structure of IBWA can lead to increased porosity and water absorption in concrete. Leachate analysis demonstrated the effective stabilization of heavy elements within the cement hydration matrix (C-S-H, C-A-S-H, etc.), meeting US EPA regulatory standards. LCA interprets that IBWA utilization of up to 10% cement replacement material and 30% sand replacement material could curtail the carbon footprint and energy demand by ~ 25–35% and 15–25%, respectively, compared to conventional cement-based mortar systems. These findings highlight IBWA’s potential to transform the construction sector, aligning it with global sustainability goals and reducing its dependence on non-renewable resources. © The Author(s), under exclusive licence to Shiraz University 2025.Item From printing to performance: a review on 3D concrete printing processes, materials, and life cycle assessment(Springer Nature, 2025) Mishra, S.K.; Snehal, K.; Das, B.B.; C, R.; Barbhuiya, S.A paradigm shift in the construction sector has been driven by 3D concrete printing (3DCP), offering automated alternatives to conventional building methods. 3DCP enhances precision, efficiency, and consistency through robotic control and advanced printhead systems while reducing material waste and enabling design flexibility. This review examines the working principles, printer classifications (gantry-based and robotic arm-based), and operational parameters, highlighting printing speed, interlayer gap time, and nozzle size and shape as critical parameters for buildability, interlayer bonding, and extrusion quality. Their influence is discussed in relation to fresh properties (flowability, pumpability, extrudability, shape retention, and buildability) and hardened properties (compressive, tensile, and flexural strength, interlayer bonding, and durability). Mix design strategies for optimizing rheology, printability, and sustainable material selection are critically reviewed. Key durability concerns such as shrinkage, cracking, and weather resistance are addressed. Reinforcement methods, including steel bars, fibers, and embedment techniques, are also discussed. A life cycle analysis reveals that 3DCP reduces carbon dioxide emissions by up to 89.2% and construction costs by 30–40% through formwork elimination. Environmental impacts (waste generation, carbon footprint, and energy use) are assessed using regional and global data, considering embodied energy, transportation, and maintenance costs. Challenges such as regulatory hurdles, high initial investment, and the absence of standardized guidelines are identified. This review covers developments from the past decade, offering valuable insights for researchers, industry professionals, and policymakers regarding the advancements, limitations, and future directions of 3DCP. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.Item Mechanical and permeability properties of hybrid fibre reinforced porous concrete(Associated Cement Companies Ltd., 2019) Snehal, K.; Das, B.B.Experimental investigation was carried out to determine the enhancement of compressive strength, flexural strength and abrasion resistance along with water permeability of porous concrete introduced with hybrid fibres (consists of equal proportion of steel, polypropylene and glass) and with two different sizes of coarse aggregate. The varying parameters in the preparation of porous concrete mix were coarse aggregate of two sizes, i.e., 6 mm and 12 mm and five different percentages of hybrid fibres (0.25 - 0.65 with an increment of 0.1). Compressive strength and flexural strength were measured at the end of two curing periods (7 and 28 days) whereas water permeability and abrasion test values were measured at the end of 28 days of curing. From the experimental findings, it is observed that compressive strength and flexural strength values increase with decrease in the size of the aggregate for control as well as fibre reinforced porous concrete. However, with respect to the measured values of permeability, it is found that with increase in size of coarse aggregates, permeability values also increases. For 28 days samples it is observed that 0.35% addition of hybrid fibres to porous concrete found to be optimum and it improved the compressive strength values by 20.24% and 19.06% for coarse aggregate sizes of 6mm and 12mm, respectively as compared to porous control concrete (without addition of hybrid fibres). Whereas, maximum flexural strength was obtained at 0.45% of addition of hybrid fibres and 31.6% (6mm coarse aggregate) increment and 24.26% (12mm coarse aggregate) increment were noticed as compared to porous control concrete. The best values for permeability were found at 0.35% of hybrid fibres and 12 mm coarse aggregate combination, whereas for abrasion resistance it was at 0.35% of hybrid fibres and 6mm coarse aggregate combination. © 2019 Associated Cement Companies Ltd.. All rights reserved.Item Early age, hydration, mechanical and microstructure properties of nano-silica blended cementitious composites(Elsevier Ltd, 2020) Snehal, K.; Das, B.B.; Akanksha, M.This study was carried out to understand the influence of nano-silica on hydration properties of binary, ternary and quaternary blended cement paste and mortar containing micro to nano sized admixtures including fly ash (FA), ultrafine fly ash (UFFA) and nano-silica in colloidal form (CNS). Characterization methods such as thermogravimetric analysis (TGA), X-ray diffraction studies (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) was employed to quantify the hydration products. Further, early age and mechanical properties were also investigated for binary, ternary and quaternary cementitious system blended with nano-silica. The optimized proportions of blended paste and mortar are designed through modified Andreasen and Andersen particle packing model. The experimental test results revealed that the optimum dosage of CNS in binary blended cement composites is 3%. The presence of nano-silica in cementitious system amplified the hydration and pozzolanic activity, thereby promoting densified microstructure at nano scale. The flow test indicated the intensified demand for water absorption and reduced workability with the rise in level of incorporation of CNS particles in cement paste. Quaternary blended mix performed superior hydration along with strength properties amongst all the blended samples. © 2019 Elsevier LtdItem Influence of Integration of Phase Change Materials on Hydration and Microstructure Properties of Nanosilica Admixed Cementitious Mortar(American Society of Civil Engineers (ASCE) onlinejls@asce.org 1801 Alexander Bell DriveGEO Reston VA 20191 Alabama, 2020) Snehal, K.; Das, B.B.; Kumar, S.The present study demonstrates the influence of integrating phase change materials (PCMs) on hydration and microstructure properties of nanosilica admixed cementitious mortar. First, the optimized dosage of nanosilica in correspondence to compressive strength was determined. Subsequently, the desired proportion of PCMs was identified pertaining to a designated compressive strength of 35 MPa at the curing age of 28 days. The hydration and microstructure studies were carried out through thermo gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. Further, thermal properties were determined by means of differential scanning calorimetry (DSC). Incorporation of nanosilica into the cementitious mortar was found to have a positive influence on early strength development and durability, however, there was found to be an increase in chemical shrinkage as compared to the control mixture. PCMs integrated cementitious mortar improved the thermal efficiency as well as reduced the chemical shrinkage, but adversely affected the mechanical, hydration, and durability properties. With respect to development of compressive strength of the cementitious mortar, it is found that n-octadecane PCMs performed better amidst other PCMs, such as paraffin and sodium carbonate hydrates. Further, studies were carried out on cementitious mortar having both nanosilica (optimized proportion) and PCMs (the best performing). From the results, it is found that cementitious mortar comprising of both nanosilica and PCMs have compensated the drawbacks of one another. Blended mortar (having both nanosilica and PCMs) showed superior strength gain at early age, better durability resistance, low chemical shrinkage, and superior thermal performance. © 2020 American Society of Civil Engineers.Item Effect of phase-change materials on the hydration and mineralogy of cement mortar(ICE Publishing, 2020) Snehal, K.; Das, B.B.The influence of direct incorporation of thermally efficient phase-change materials (PCMs) on the hydration and mineralogical properties of cement mortar was investigated. To assess the viability of bulk addition of PCMs to a cementitious system, tests of the early age, hydration, mechanical, durability and mineralogical properties were carried out. Organic PCMs showed an increase in setting time, while inorganic materials exhibited fast setting characteristics. Surface temperature was also found to be lower for cement paste with incremental dosages of PCM. However, chemical shrinkage was found to be reduced in the presence of PCM except for the inorganic type. It was observed from the results that PCMs negatively influenced the rate of strength development of a cementitious mortar. The slow rate of strength development was found to be attributed to interrupted hydration, which was confirmed through mineralogical studies. Further, from the thermo-gravimetric analysis, it was observed that the presence of PCMs in a cementitious system increased calcium hydroxide content and reduced the content of water related to hydration products. © 2020 ICE Publishing: All rights reserved.Item Acid, alkali and chloride resistance of binary, ternary and quaternary blended cementitious mortar integrated with nano-silica particles(Elsevier Ltd, 2021) Snehal, K.; Das, B.B.This paper investigates the quantification of ettringite (Ca6Al2(SO4)3(OH)12.26H2O, AFt), gypsum (CaSO4.2H2O, Gy) and Friedel's salt (Ca4Al2(OH)12Cl2.4H2O, Fs) formed for binary, ternary and quaternary blended cementitious mortar mixes that were exposed to acid (H2SO4), alkali (Na2SO4) and chloride (NaCl) solutions. Quantification was carried out through a thermogravimetric analyzer by characterizing the mass loss associated to the decomposition of these compounds at specific boundaries of temperature (50–120 °C for AFt, 120–150 °C for Gy and 230–380 °C for Fs). Binary, ternary and quaternary blended cementitious mortar mixes were designed by adopting modified Andreasen and Andersen particle packing model. A long-term exposure period was spanned to the duration of 180 days for all kind of aggressive media and its effect on engineering properties of blended cementitious mortar were measured. Deterioration due to acid (H2SO4) exposure is found to be more intense due to the synergistic action of acid and sulfates. It is to be noted that for acid exposure period of 180 days, control mortar underwent an acute density and strength losses of 18% and 59%, respectively. However, cementitious mortar mix consisting of 3% nano-silica performs the best against aggressive media. The optimistic resistance to the formation of AFt and Gy was also found to be offered by quaternary blended mix. A similar trend was also observed in the formation of Fs for the mortar mixes exposed to NaCl solution. Significant improvement in particle packing density by the inclusion of micron to nano sized finer particles for quaternary blended mortar mix has minimized the permeable porosity, thus reduced the susceptibility to the formation of voluminous compounds. Enhanced pozzolanic activity due to the presence of nano-silica could be one of the primary reasons for quaternary blended mortar to perform better against the aggressive media that can be adopted in the practice considering sustainability and economical point of view. © 2021 Elsevier LtdItem Influence of aggressive exposure on the degradation of nano-silica admixed cementitious mortar integrated with phase change materials(Elsevier Ltd, 2022) Snehal, K.; Das, B.B.; Barbhuiya, S.The objective of the present study is to evaluate the stability of cementitious mortar incorporated with phase change material (PCM, n-octadecane) at aggressive exposure conditions such as acid (1% H2SO4), alkali (5% Na2SO4) and chloride (5% NaCl). Thermogravimetric analysis (TGA) was performed to characterize and quantify the amount of deleterious compounds such as ettringite (Ca6Al2(SO4)3(OH)12·26H2O, AFt), gypsum (CaSO4·2H2O Gy) and Freidel's salt (Ca2Al(OH)6(Cl, OH)·2H2O, Fs) formed due to the action of SO42− (acidic and alkaline media) and Cl− (chloride media) ions at the continuous exposure period of 180 days. Mass loss associated to the thermal degradation of n-octadecane PCM (CH3(CH2)16CH3) at various exposure solutions was also calculated at the temperature boundary of 250–300 °C. This study also highlights the introduction of optimized nano-silica dosage (3%) into the PCM based cementitious mortar to counteract the undesirable facets of PCMs on cementitious system. Results revealed that incorporation of PCM in cementitious mortar augmented the amount of AFt, Gy (at acid and alkali exposure solution) and Fs (at chloride exposure solution) formation, responsible for the amplified rate of deterioration. It is important to be noted that after long term exposure of 180 days no traces of PCM was observed in PCM based cementitious mortar mixes, which signifies the mixes no longer holds the capacity to store energy. However, co-occurrence of nano-silica (3%) in PCM based cementitious mixes curtailed the negative impact of PCM on cementitious mortars exposed to aggressive conditions significantly. Further, differential thermogravimetric (DTG) curve shows an additional endothermic peak at 250–300 °C for 3% nano-silica modified PCM based cementitious mixes even after exposure to aggressive ions that implies the ability of the mix to sustain the thermal efficiency characteristics of PCMs. © 2022 Elsevier LtdItem Pozzolanic Reactivity, Hydration and Microstructure Characteristics of Blended Cementitious Composites Comprising of Ultrafine Particles(Springer Science and Business Media Deutschland GmbH, 2022) Snehal, K.; Das, B.B.; Sudhi, A.; Pandey, D.Performance of ultrafine fly ash (UFFA, 5–10 µm) and fly ash (FA, 45–50 µm) particles in cementitious composites was investigated individually as well as in combination. To study the physicochemical behaviour of blended cementitious composites, engineering properties and pozzolanic reactivity test were conducted. Further, characterization techniques such as thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX) were employed. The results showed good amplification in the development of early compressive strength and durability on admixing ultrafine particles of fly ash (UFFA) in cementitious system. Particle size and specific surface area of UFFA greatly influenced on the phase assemblages of cementitious composites, i.e. due to enriched pozzolanic reactivity which reduced Ca/Si atomic ratio (≤ 1.82) in the pore solution of cementitious matrix. On contrary, the presence of UFFA particles in cementitious composite mix developed disjoining pressure in addition to self-desiccation thereby induced early age cracks and also reduced the workability in correspondence to that of FA particles. Further, use of UFFA in conjunction with FA particles, cementitious composites showed much superior performance in terms of both physical and chemical characteristics, which necessitates the crucial need of admixing micron and submicron size particles in the design of sustainable and high-performance cementitious composites at this point of time. © 2022, The Author(s), under exclusive licence to Shiraz University.