High Volume Fly Ash Research Articles

Utilization of high-volume fly ash in pervious concrete mixtures for mangrove conservation

In environmental conservation, mangrove forests play a crucial role. Retransplanting mangrove propagules, however, faces challenges, and success rates are notably low. Achieving an optimal protector for propagules, balancing strength without impeding growth, is challenging. Mangrove propagules require a temporary protector with an optimal balance, neither too weak nor too strong, to shield them from current waves which is difficult. We propose using pervious concrete pots with high-volume fly ash activated with low NaOH concentrations. The investigation focuses on the influence of the mixing procedure on workability, compressive strength, and mineral composition. The novel discovery in this study is the specific sequence of stirring the ingredients using an alkali activator, which adds an interesting dimension to the research. It is recommended to adopt Sequence 2 in pervious concrete production, where NaOH dissolved FA in the mixture forming albite as N-A-S-H gel product. It surely enhanced both workability and the strength confirming uniform application processes. The two recommended variants, PFS-60 and PFBS-50, effectively utilize coal ash, meeting the target compressive strength range of 3–5 MPa and providing support for mangrove pots over a 3–4 year period. Notably, both compositions maintained consistent mechanical properties during exposure to tidal conditions for 240 days.They exhibit high permeability (694 liter/m²/minute), facilitating efficient water passage without sediment entrainment.

Evaluating Bulky PVA-ECC Mortar Developed with River Sand, Silica Fume, and High-Volume Fly Ash: A Focus on Short- and Long-Term Compressive Strength

Evaluating Bulky PVA-ECC Mortar Developed with River Sand, Silica Fume, and High-Volume Fly Ash: A Focus on Short- and Long-Term Compressive Strength

Early strength enhancement of high-volume fly ash mortar using accelerating admixtures

High-volume fly ash mortar is considered a "green" material, a sustainable development solution for the construction industry, in which the fly ash replacement Portland cement content is over 50%. However, this material has the major disadvantage of slow strength development, especially at an early age, which limits its applicability. To overcome the above disadvantage, the individual or combined addition of lime Ca(OH)2, silica fume, and/or accelerating admixtures including sodium thiocyanate (NaSCN), diethanolamine (DEA), and glycerol (Gly), etc. have been interested recently. In this study, to enhance the early strength of mortars with fly ash content to replace 60÷80% of Portland cement, a three-component accelerating admixture of NaSCN, DEA, and Gly (2:1:0.5 by the mass) was used with different ratios of 0.21÷0.49 % by the total powder mass, combined with a reasonable amount of lime, silica fume supplement as presented in previous research. Experimental results showed that the optimal accelerating admixture content is 0.35% by weight of powder, combined with 6% silica fume and the additional amount of lime is 5%; 10%; and 15% corresponding to mortars using fly ash of 60%; 70% and 80%, respectively to improve early strength of mortars that are suitable for structural use (R3 ≥ 13MPa, 3 days old). In addition, the influence of the additives used on the initial setting time of high-volume fly ash mortars was also discussed.

Influence of fly ash on rheological behaviour of HVFA concrete

High-volume fly Ash (HVFA) concrete has gained significant attention recently due to its potential for reducing environmental impact and improving long-term durability. This project investigates HVFA’s influence on concrete rheology, aiming to explore its applicability in sustainable construction. HVFA concrete mixes M1 (30% fly ash), M2 (40% fly ash), and M3 (50% fly ash) were prepared, varying fly ash percentages as a partial cement replacement. Fresh concrete tests, including slump cone and flow table tests, assessed workability and flow characteristics. Hardened samples underwent compressive and split tensile strength tests to evaluate mechanical properties. Results provided insights into HVFA concrete rheology, focusing on workability, flowability, and mechanical performance. Additionally, the study explores potential environmental benefits and challenges linked to HVFA concrete. These findings aid in advancing sustainable concrete technologies, offering crucial insights for engineers, architects, and policymakers seeking innovative, eco-friendly construction materials and practices while addressing environmental challenges related to HVFA concrete.

High-Volume Fly Ash Engineered Cementitious Composite for Underground and Hydraulic Engineering

High-Volume Fly Ash Engineered Cementitious Composite for Underground and Hydraulic Engineering

ANN modeling of mechanical properties in high-volume fly ash concrete: multi-objective cost optimization using NSGA-II for sustainable construction

ANN modeling of mechanical properties in high-volume fly ash concrete: multi-objective cost optimization using NSGA-II for sustainable construction

Thermal Cracking in High Volume of Fly Ash and GGBFS Concrete

Supplementary cementitious materials (SCMs) such as fly ash and ground granulated blast furnace slag (GGBFS) are found to control the maximum temperature and the accompanying thermal gradients effectively. However, SCMs also lead to low early age strength development. Thus, it is crucial to understand the cracking behaviour of SCMs-based concrete affected by the mix design parameters. In this paper, the thermal cracking resistance was evaluated using a rigid cracking frame (RCF) with a computer-controlled temperature profile. The temperature profile was determined using the software ConcreteWorks by assuming the centre point of the mass concrete. The free shrinkage frame (FSF) and match-curing oven follow the same temperature profile as RCF to measure the free total deformation and time-dependent mechanical properties of concrete, respectively. An analytical model was proposed to calculate the autogenous shrinkage and the thermal stress separately. A time-dependent cracking risk coefficient allowing to estimate the risk of early age cracking of concrete was also proposed.

Effect of Accelerators on High Early Strength Concrete (HESC) Using High Volume Fly Ash

Applying large quantities of fly ash for the production of High Early Strength Concrete (HESC) is a challenge for researchers in the utilization of quality, inexpensive, and environmentally friendly materials. A high volume of fly ash in concrete, however, reduces the initial compressive strength of the concrete. For this reason, it is necessary to use admixture additives in the concrete mixture to get the expected performance. This research seeks to identify the optimal HESC mix design using fly ash 50% of the total cementitious by adding a superplasticizer and accelerator to obtain a high initial compressive strength. Three variations of HESC, namely HESC-12, HESC-14, and HESC-16, were made using a superplasticizer and accelerator with different doses. Each variation uses 12 liters of superplasticizer and different accelerator volumes: 12 liters, 14 liters, and 16 liters. Specimen testing was carried out on fresh and hard concrete. Fresh concrete was subjected to a slump test, whereas hard concrete was subjected to compressive tests at 18 hours, 24 hours, 3 days, and 28 days of age. The average slump flow values for HESC-12, HESC-14, and HESC-16 (cm) were 78, 79.5, and 80, respectively, demonstrating that all HESC samples are classified as self-compacting concrete (SCC). According to the results of density tests conducted on all specimens ranging from 2461 to 2538 kg/m3, all specimens are included in the category of normal-weight concrete. Within the range of 29.8 to 35.3 MPa for the initial compressive strength of HESC at 24 hours of age, it can be concluded that all HESC specimens fulfill the criteria for high early-strength concrete. The addition of the right type and dosage of chemical admixture is a solution to overcome the weakness of applying fly ash in high-early-strength concrete.

Utilisation of electrolytic manganese residue as a sulphate activator in producing concrete blocks with high-volume fly ash

Electrolytic manganese residue has been largely generated and accumulated, which poses a threat to the sustainable development of the electrolytic manganese metal industry. This paper explores the feasibility of utilising pretreated electrolytic manganese residue and fly ash in the production of concrete blocks. The pretreated electrolytic manganese residue is used as an activator to react with the alumina and portlandite in the mixture. The volume of permeable voids, compressive strength, and drying-wetting performance of the blocks were estimated, followed by the characterisation of their microstructure and the leaching behaviour of hazardous elements. The results show that replacing sand with 0–30 wt% pretreated electrolytic manganese residue can improve the blocks' compressive strength and reduce the volume of permeable voids due to the filler effect of pretreated electrolytic manganese residue and the promoted formation of ettringite. However, increasing the pretreated electrolytic manganese residue content compromises the blocks’ water resistance due to the presence of gypsum. Substituting 0–30 wt% of ordinary Portland cement with fly ash in the blocks contributes reactive SiO2 and Al2O3 to the system with the pretreated electrolytic manganese residue as a sulphate activator. This further facilitates the formation of ettringite which can bridge micro-particles and fill pores, enabling the concrete blocks with ordinary Portland cement and fly ash to attain comparable properties to those with ordinary Portland cement only. Moreover, leaching tests demonstrate that hazardous elements in electrolytic manganese residue can be efficiently immobilised in concrete blocks. The incorporation of 0–30 wt% fly ash enhances the solidification of Mn in the blocks due to the intensified ion substitution and physical encapsulation emanating from the facilitated formation of ettringite. Overall, this paper showcases a sustainable technical pathway for the utilisation of electrolytic manganese residue in concrete blocks with high-volume fly ash.

Literature Review: High Volume Fly Ash Concrete

The construction industry is experiencing immense pressure for substitutes for traditional building materials in the modern world. In the first half of 2020–2021, just under 57.93 percent of the total amount of fly ash generated in the nation was reused. The remaining material was thrown away of in landfills, spewing toxic substances into the immediate vicinity. Numerous creative proposals have been put forward all around the world that aim to increase the average amount of fly ash utilized during constructing. The most promising domains are geo polymer and high volume fly ash concrete construction. This study encompasses the research undertaken on each of these areas by an assortment of professionals internationally. Their attempts paid off, yielding concrete that exhibited barely any heat accumulation during its hydration process negligible sagging, enhanced versatility, and a modest dense utilizing a a great deal of ash from fly ashes. The outcomes derived from geo polymer concrete construction comprised outstanding durability, acidic obstructions, plus an elevated fly ash content, with characteristics analogous with that from Rcc constituents. Furthermore, the a project-specific strategy prescription is anticipated to be generated

Behavior of a high-volume fly ash fiber-reinforced cement composite toward magnesium sulfate: a long-term study

Behavior of a high-volume fly ash fiber-reinforced cement composite toward magnesium sulfate: a long-term study

Synergistic impacts of high-volume fly ash and sugarcane bagasse ash on performance of cementitious composites reinforced with polyvinyl alcohol fibers

Disposal of waste materials in fertile land is one of the pressing environmental issues, disrupting human, animal, and plant life. This has led the researchers to process and use such waste in ecofriendly construction products like mortar and concrete. Their usage as supplementary cementitious materials (SCMs) would reduce the quantity of cement used in the manufacturing of cement-based materials, lowering CO2 emissions related with cement production. In this regard, this study examines the feasibility of replacing high-volume of ordinary Portland cement (OPC) in engineered cementitious composites (ECC) with two widely used waste materials, sugarcane bagasse ash (SCBA) and fly ash (FA) as SCMs. Five different mixes were produced, each containing a fixed amount of polyvinyl alcohol (PVA) fibers at a dosage of 1.5 % by volume of the mix and a constant cement content of 50 % by weight of the binder (OPC + FA + SCBA). However, FA was replaced with SCBA in these mixes up to 100 % by the combined weight of the waste materials (FA + SCBA) in increments of 25 % (i.e., FA100-SCBA0, FA75-SCBA25, FA50-SCBA50, FA25-SCBA75, and FA0-SCBA100). The results showed that the compressive strength and flexural strength of the composites with the increasing levels of SCBA were reduced. Interestingly, the 28-day compressive strength of composite incorporating 50 % FA and 50 % SCBA was still as high as 25.58 MPa, which satisfied the minimum compressive strength requirement of ASTM C270, making the newly produced ECC suitable for use in normal construction works and repairs. The same optimum mix (FA50-SCBA50) produced an average density of 1867.96 kg/m3 as a result of substituting a significant amount of binder with SCBA, demonstrating that it has evolved into a lightweight engineered cementitious composite. Furthermore, the ultrasonic pulse velocity of the mixes decreased whereas water absorption increased as the proportion of SCBA to FA increased. According to microstructural analysis, unreacted SCBA particles were mostly responsible for the detrimental effects of rising SCBA levels on properties of ECC. Based on the aforementioned results, this research concludes that sugarcane bagasse ash, when combined with fly ash, could be a viable alternative for replacing regular cement up to 50 % by weight in the production of cost-effective and environmentally friendly cementitious composites.

Incorporation of Bottom Ash as Aggregates in High-Volume Fly Ash (HVFA) Concrete

Research has been conducted on the utilization of coal combustion residues, specifically fly ash and bottom ash, in order to produce concrete products that meet national standards. Fly ash is employed as a high-volume replacement for cement in what is known as high-volume fly ash (HVFA) concrete. On the other hand, bottom ash is used as both fine and coarse aggregates, serving as a substitute for sand in the concrete mixture. Various characterizations were performed, encompassing the examination of the constituent minerals, crystallinity levels of bottom ash, water absorption, porosity, abrasion resistance, compressive strength, and morphological properties of the concrete specimens. Both fly ash and bottom ash exhibit significant proportions of SiO2, Al2O3, Fe2O3, and CaO, which possess pozzolanic properties and contribute to the compressive strength of the concrete. Concrete samples were produced with varying amounts of bottom ash and other ingredients according to the mix design. The highest compressive strength achieved after 28 days of curing was 27.57 MPa (designated as code B5), accompanied by the lowest porosity of 6.25%. Specimens with code B5 also displayed the lowest abrasion rate of 0.02 mm/minute and water absorption of 1.1%. These results suggest that the formulated mixture has the potential for developing concrete products suitable for walls and paving, adhering to the requirements specified in standard SNI 03-0349-1989 and SNI 03-0691-1996.

Value-added utilization of steel slag as a hydration heat controlling material to prepare sustainable and green mass concrete

Value-added utilization of steel slag as a hydration heat controlling material to prepare sustainable and green mass concrete was systematically investigated in this study. Effects of high-volume steel slag on reducing the heat release and temperature rise as well as on the workability, strength and durability of mass concrete were studied and compared with those of high-volume fly ash. Results show that the addition of high-volume steel slag efficiently reduces the heat release of the blended system. Steel slag demonstrates superior heat reduction compared to fly ash, especially at 25 °C (reduced by 35%), and is comparable/closer at 50 °C. High-volume steel slag concrete shows reducing temperature rise (especially before 7 d), and presents smaller porosity, prolonged setting time, slower fluidity loss, good compressive strength, and permeability resistance compared with high-volume fly ash concrete. The utilization of steel slag as a hydration heat controlling material to prepare sustainable and green mass concrete with blast furnace slag is a potential and value-added utilization method of steel slag, which is in favor of sustainability.

Advanced regression models for assessing the strength of multi-walled carbon nanotube-modified high-volume fly ash concrete

Advanced regression models for assessing the strength of multi-walled carbon nanotube-modified high-volume fly ash concrete

Effect of Nano-SiO2/Steel fiber on the mechanical properties and sulfate resistance of High-Volume fly ash cement materials

The flexural strength, compressive strength, water absorption, and sulfate resistance of high-volume fly ash cement mortar hybrid containing 0–2.5 wt% nano-silica dioxide (Nano-SiO2, NS) and 0–2.0 vol% steel fibers (SF) were studied in this paper. Fly ash (FA) was used to replace 50 wt% of Portland cement. The resistance to sulfate attack was tested by exposing the specimens to 5.0 wt% sodium sulfate solution, and the flexural strength, compressive strength, and mass loss after 3, 6, and 9 months of erosion were determined. Specimens cured at normal condition were tested at the same ages for comparison. Moreover, the microstructure and pore structure were also investigated. The test results show that the combined addition of NS and SF significantly enhanced the flexural and compressive strength of high-volume fly ash mortar and significantly reduced its water absorption. Compared with control mortar, the addition of 1.0 vol% SF and 2.0 wt% NS increased the flexural and compressive strength by 70.6 % and 53.7 % respectively at the age of 28 days, and the water absorption of mortar was decreased by 45.0 % at the age of 90 days. The hybrid addition of NS and SF improved the sulfate resistance of mortar, reduced the mass loss rate of sulfate attack, and enhanced the residual strength of mortar after sulfate attack. In addition, the mercury injection test showed that adding NS and SF can obviously refine the pores of high-volume fly ash mortar, and reduce the internal average pore diameter.

Experimental Investigation of the Bonding Behavior of High-Volume Fly Ash Self-Compacting Concrete Reinforced with Steel and GFRP Bars

This paper investigated the bond strength between reinforcement steel and GFRP bars embedded in high-volume fly ash concrete and conventional concrete mixtures. This research evaluated two mixes: conventional concrete, and 50% replacement cement with Class F fly ash. According to RILEM recommendations, eight hinged beams were employed to evaluate the bond strength of the concrete mixes.This investigation showed good bonding for concrete mixes containing 50% fly ash compared to conventional concrete. GFRP bars also showed good bonding, better than steel bars in the case of small diameters (10 mm), but lower bonding in the case of larger diameters (16 mm).

Performance evaluation of HVFA content in cement concrete incorporating filler additives: rheology and mechanical properties

For a better sustainable progressive world, construction industry turned wider gradually. It is well known fact that cement concrete is main component of construction for our modern civilization. Now days, fly ash is used as the most potential replacement material in cement concrete, as production of cement very badly harm our environment. Reports show that one tonne cement produces one tonne carbon dioxide in our environment and responsible for global warming. After successive research work, it is proven that replacement of high volume fly ash (above 50%) which is pozzolanic in material (consists of siliceous and aluminous compounds) in cement paste helps to achieve high strength, porosity, heat of hydration, micro structure as well as very economical and eco-friendly against normal cement paste. This paper mainly highlights on the detailed study of rheological and strength properties of high volume fly ash concrete (50%-70% replacement of cement in various grades of fly ash mixed as per IS standards) in addition with various additives and melamine based admixture. In addition to this, other properties such as consistency, hardening and stiffening, workability, mechanical properties are studied. This overall study include experimental program on various concrete specimen with varied cementitious content along with admixtures.

Behavior of Polymer Modified High Volume Fly Ash Concrete (PMHVFAC)Produced with Hybrid Textile Fibers

Behavior of Polymer Modified High Volume Fly Ash Concrete (PMHVFAC)Produced with Hybrid Textile Fibers

Investigation of physicochemical processes taking place in chemically activated very high volume fly ash mixtures

In order to reduce the negative impact of cement production on the natural environment, and in particular to reduce CO2 emission, new types of binders are sought. It is beneficial to use supplementary cementitious materials, such as fly ash. A very high volume of fly ash and a reduced amount of cement in the binder can, however, result in deterioration of some properties of the final composite. Such systems require activation. The aim of this work was to investigate the effects of different activators: spent aluminosilicate catalyst (very active pozzolanic material), Na2SO4 and Ca(OH)2 on the hydration/activation processes and development of 28-day compressive strength of the blends containing a very high volume of fly ash. Activators were introduced into the system in various combinations: alone or in mixtures. The following research methods were used: calorimetry, thermal analysis, X-ray diffraction and IR spectroscopy. It was shown that each type of activation accelerates cement hydration, improves pozzolanic activity and increases compressive strength compared to the results of non-activated reference sample. However, the activation kinetics and mechanism of interaction are different for different activators. The most promising results were obtained for the combination of three activators: spent aluminosilicate catalyst, Na2SO4 and Ca(OH)2.