Papers by Keyword: Fly Ash

Abstract: This study evaluates the effect of acid attack on the behavior of concrete containing bentonite and fly ash. The concrete mixes contain varying dosages of bentonite mixed with a constant ratio of 10% fly ash. The concrete mixes include A0, A1, A2, A3, A4, and A5, which contain 0%, 10%, 20%, 30%, 40%, and 50% bentonite, respectively. Experimental results reveal that the addition of 10% fly ash along with 10% bentonite can show significant resistance toward acid attack. The concrete mix A1, containing 10% fly ash and 10% bentonite, loses only 1.1% of its mass as compared to the controlled mix of concrete, which shows a significant loss of its mass up to 8.4%. Microstructural analysis of concrete specimens reveals significant changes in hydration products using scanning electron microscopy (SEM). The addition of 10% bentonite along with fly ash creates a denser microstructure due to the formation of calcium silicate hydrate gel and refines the internal pores of the concrete, which provides a significant resistance towards acid attack. In addition, higher dosages of bentonite lead to a porous and loose microstructure, which becomes susceptible to microcracking and spalling.

Abstract: Pakistan’s construction industry is facing increasing pressure to adopt sustainable practices due to rapid urbanization, rising CO₂ emissions, and resource depletion. Rice husk ash (RHA) and fly ash (FA)—agricultural and industrial by-products—present significant potential as supplementary cementitious materials (SCMs) for sustainable concrete. This paper reviews global research on the physical, chemical, and microstructural properties of RHA and FA, emphasizing their combined use in enhancing strength, durability, and resistance to environmental degradation. To align with the theme of Nano-Driven Material Innovation, the study highlights the importance of particle size distribution analysis, SEM/TEM imaging, and other nano-scale characterizations for understanding pozzolanic reactivity and microstructural improvements. The work also explores the potential integration of these materials into Pakistan’s construction industry, considering local availability, cost implications, and environmental benefits. By replacing a portion of Portland cement with these waste materials, Pakistan can reduce its carbon footprint, mitigate waste disposal issues, and promote a circular economy in construction. The paper concludes with a proposed framework for pilot-scale implementation and further experimental validation tailored to Pakistan’s conditions. In the long term, such research can support the establishment of dedicated organizations or firms in Pakistan that pioneer sustainable construction practices, translating academic innovation into real-world application.

Abstract: A concrete mixture formulation consisting of industrial wastes such as fly ash and gypsum from ceramic mold waste as partial replacements for cement was developed in this two-part study to lessen the carbon footprint from processing the conventional materials used in the construction industry. The first part aims to determine the optimum composition of the ternary binder (cement, fly ash and recycled gypsum) and the curing period (7, 28 and 90) that will provide the highest compressive strength for the casted concrete cylinders. The second part focuses on establishing the effective polypropylene fiber (PPF) dosage, utilizing the pre-optimized binder composition. The structural integrity of the concrete cylinders was evaluated through compressive strength and split tensile tests following water curing periods of 7, 28, and 90 days. Results from the initial mechanical tests revealed that the optimum ternary binder composition was C60-F37.5-G2.5 cured for 90 days. While fiber reinforcement typically has limited impact on compressive strength, the addition of 1.5% PPF yielded better long-term compressive strength development compared with other PPF dosages. For tensile strength, 0.5%-1% PPF achieved the highest values at 28 days, whereas 1.5% PPF provided the peak performance under prolonged curing at 90 days. This shift in behavior is attributed to the progressive increase in fiber-bridging effectiveness over time. Findings from these mechanical tests were supported by the results from X-Ray Diffraction (XRD) analysis and optical microscopy.

Abstract: The construction industry plays a vital role in the economic development and overall progress of any country. Construction activities have significant impact on the economy, but their environmental consequences cannot be overlooked. The excessive use of construction materials particularly cement and steel, which are among the most commonly used construction materials, has become a major environmental concern, as these materials are also key sources of carbon emissions. Moreover, the raw materials required for the preparation of cement and Steel are also depleting at a rapid pace. Therefore, it is necessary to conduct research studies to find new alternative materials which can reduce the consumption of cement and steel in the concrete. Fly ash can be used as binding agent in concrete as it has good cementation properties and is abundantly available. To enhance the mechanical performance of geopolymer concrete (GPC), polypropylene fibers (PPFs) were incorporated in varying ratios (0.5% to 1.5% by volume). The samples were prepared to test the mechanical and durability properties of the concrete. Compressive Strength, Flexural Strength, and Split Tensile Strength test was carried out to conclude the mechanical properties of the geopolymer concrete against different percentages of polypropylene Fiber. Acid attack and rapid chloride permeability tests were conducted out to evaluate the durability of the concrete. The research findings depicted that the greatest compressive strength and split tensile strength are obtained at 1% PPFs GPC. The least amount of chloride penetration was demonstrated by GPC, at 1.5% PPFs.

Abstract: Using cement as the primary material for making concrete, around 7%-15%, requires a significant amount of energy and generates abundant waste, thus significantly impacting the environmental conditions. Innovative materials are needed as alternatives to cement. Fly ash, as an environmentally friendly material, can be a solution to minimize the use of cement. The selected fiber is Poly-Vinyl Alcohol (PVA) fiber due to its high tensile strength, which can effectively inhibit the rate of crack development occurring in the beams. The research process was divided into two stages: geopolymer mortar compressive strength testing and beams flexural testing. Compressive strength testing of geopolymer mortar was conducted on 50x50x50 mm cube samples, tested at ages of 3, 7, and 28 days using both air curing and moist curing methods. Geopolymer mortar was created using fly ash as the base material, along with activators such as Sodium Hydroxide (NaOH) and Sodium Silicate (Na₂SiO₃). Meanwhile, flexural beams were tested in 5 samples of 150x200 mm beams with a length of 3300 mm each. The samples consisted of a control beam, a beam reinforced with commercial grouting mortar, a beam reinforced with commercial grouting mortar and PVA geopolymer fibers, a beam reinforced with geopolymer mortar, and a beam reinforced with geopolymer mortar and PVA fibers. The research results indicated that adding PVA fibers to geopolymer mortar could enhance the maximum load-bearing capacity and stiffness of the beams. Regarding failure modes, beams reinforced with PVA-free geopolymer mortar experienced delamination failure, whereas beams reinforced with PVA-containing geopolymer mortar encountered debonding failure.

Abstract: Cement contributes CO₂ emissions to the atmosphere, which is harmful for human health. Several researchers have conducted experiments to find materials that have the potential to be used as cement substitutes. Fly ash and perlite are wastes that contain silica as well as high aluminum, so they have potential as cement replacement materials. In this study, geopolymer concrete mixtures were made using fly ash and perlite with a NaOH concentration of 10M – 16 M, a Na₂SiO₃/NaOH ratio of 2.5 and alkaline solution to fly ash ratio (AA/FA) of 0.5. The curing method used was using an oven at 80 °C for 16 hours. From the experimental results, the optimum compressive strength was 28.470 MPa with a 12M NaOH concentration. The optimum flexural strength was 2.387 MPa with a NaOH concentration of 12M.

Abstract: Rigid pavement is a type of pavement that uses cement as the main binding material and has a high level of stiffness. The prolonged use of cement has increasingly negative impacts on the environment. Using geopolymer as a substitute for cement can be an eco-friendly alternative solution. Geopolymer is an environmentally friendly material that can be developed as an alternative to cement concrete in the future. The purpose of this study is to determine the compressive strength of geopolymer concrete using rice husk ash and shell as fine aggregates in rigid pavement. The research method used is experimental. The method used for mix design calculation is AASHTO 1993, by making 8 test specimens. Each test specimen uses 4 aggregate and binder ratios, which are 75:25, 70:30, 65:35, and 75:25, each with 2 alkaline activator ratios, which are 3:1 and 5:2. The compressive strength testing of the specimens was conducted at 28 days. The concrete quality used, K225, is equivalent to 18.68 MPa. The compressive strength testing of geopolymer concrete achieved optimum compressive strength at a variation of 65:35 aggregate, 3:1 alkaline, 5% rice husk ash, and 5% shell, which was 18.9667 MPa. At the variation of 75:25 aggregate, 3:1 alkaline, 5% shell, the highest value was 21.4013 MPa. Based on the type of concrete according to its compressive strength, geopolymer concrete with fly ash, rice husk ash, and shell is classified as normal concrete because its compressive strength exceeds 15 MPa and can be a substitute for cement with relatively low strength.

Abstract: Water resources are crucial in any region's overall natural resource complex. This research focuses on addressing these pollution issues through water treatment processes. The primary objective of this study was to examine the adsorption of phosphates using both natural and synthetic adsorbents, particularly aluminosilicates. Under static and dynamic conditions, the research assessed the sorption characteristics of natural zeolite, specifically clinoptilolite obtained from the Sokyrnytsia mineral deposits. Results indicated that the adsorption of phosphates is more effective in acidic environments. It was observed that clinoptilolite exhibits a higher adsorption capacity for unsubstituted phosphates, which diminishes when alkali metal ions replace orthophosphoric acid. Additionally, the study highlighted the significant influence of pH levels on the sorption properties of clinoptilolite, especially about P₂O₅. The kinetic coefficients of the adsorption process were determined using experimental data and theoretical frameworks. Furthermore, mathematical modelling was employed to describe the adsorption dynamics of the active components by granular sorbents, effectively capturing the transient nature of diffusive-kinetic processes in complex, multicomponent systems. This research deepens our understanding of phosphate adsorption mechanisms. It provides valuable insights into optimising water treatment strategies using natural adsorbents, which could play a critical role in mitigating the effects of water pollution in the region. Zeolites derived from fly ash produced by the Dobrotvir thermal power plant have been synthesised and modified to enhance their properties. This study focuses on the characteristics of these zeolites, with a particular emphasis on thermogravimetric analysis, to understand their stability and performance under varying conditions. The adsorption capabilities of the natural zeolite were tested against common pollutants found in wastewater from meat-processing plants, specifically targeting ammonium and phosphate contaminants. Experimental data allowed for determining equilibrium adsorption capacities and corresponding isotherms were constructed at a standard temperature of 20°C. The results indicate that zeolite adsorbs phosphates more effectively than ammonia nitrogen. Further analysis revealed that clinoptilolite's adsorption capacity is higher when interacting with single-component systems but decreases when it simultaneously adsorbs two different substances from the solution. This decrease suggests competitive adsorption dynamics when multiple contaminants are present. Given the finite availability of natural zeolite resources, this research highlights the importance of synthesising synthetic zeolites as a sustainable alternative.

Abstract: Rubberized cementitious composites are gaining focus in sustainable construction. Crumb rubber, sourced from waste tires, is used as a partial replacement for sand in concrete. However, rubber's low density, elasticity, and hydrophobic nature reduce workability and mechanical strength, owing to voids and poor compaction. To address these issues, supplementary cementitious materials (SCMs) like silica fume and fly ash, along with polypropylene (PP) fibres, were incorporated in this study. A control mortar mix with a 1:4 cement-to-sand ratio was established, and 10% of the sand was replaced by crumb rubber. SCMs were added at 5% by mass of cement, PP fibres at 0.1% by volume, and a water-reducing agent at 2% by mass. The results demonstrated that the flow-ability was reduced by 50%, reflecting the stiffening effect of rubber, but the compressive strength remained comparable to that of the control specimens due to the beneficial impact of silica fume, fly ash, and fibres. Density decreased by 19% due to the rubber's low density. However, when this mix was applied to concrete, it resulted in shear slump and segregation, as the rubberized mortar was insufficient to cover the coarse aggregates. This suggests that sand replacement in concrete should be done by volume rather than mass to prevent these issues and ensure proper aggregate coverage.

Abstract: The construction industry is facing increasing pressure to adopt sustainable and eco-friendly practices in response to the growing concerns over environmental degradation and climate change. Among the various innovative materials being explored, geopolymer mud blocks have emerged as a promising alternative to traditional construction materials such as cement and fired clay bricks. These blocks are characterized by their eco-friendly composition, which typically involves the use of industrial by-products like fly ash, metakaolin, and other aluminosilicate materials, activated through an alkaline solution. This process results in a material that not only exhibits superior structural integrity but also significantly reduces the carbon footprint associated with construction.This paper provides a comprehensive review of the material composition of geopolymer mud blocks, detailing the various raw materials used and the chemical reactions that confer strength and durability to the blocks. The review also delves into the structural properties of these blocks, including their compressive strength, thermal insulation capabilities, and resistance to environmental factors such as moisture and temperature fluctuations. Additionally, the paper explores the ecological impacts of geopolymer mud blocks, emphasizing their potential to reduce greenhouse gas emissions, minimize resource depletion, and promote the use of industrial waste, thus contributing to a more circular economy.Finally, the paper looks forward to the future prospects of geopolymer technology in the construction industry, suggesting potential pathways for overcoming the current limitations and further enhancing the sustainability of construction practices. By providing a holistic view of geopolymer mud blocks, this review aims to contribute to the growing body of knowledge on sustainable construction materials and to support the transition towards greener building practices on a global scale.