Fly Ash Aggregate Research Articles

Concretes meeting the requirements of sustainable construction

The article concerns the production of lightweight geopolymer concretes based on raw materials from alkali-activated waste, which is consistent with the doctrine of sustainable construction. Fly ash, which is the main component of these geopolymer composites, constitutes energy waste and causes lower emissions of greenhouse gases and other pollutants than traditional cement. The article presents the optimisation of the geopolymer concrete recipe with different dosages of fly ash (200, 300, 400, 500, 600 and 700 kg/m3) and two recipes, the first of which is based on the use of fly ash aggregate, the largest fraction of which was subjected to surface impregnation, and the second one is based on the use of aggregate without any impregnation. Both recipes use an alkaline solution for alkaline activation with a concentration of 6 mol/dm3. Compressive strength tests and apparent density were carried out on the samples. The adequacy of the use of surface impregnation has been demonstrated in the case of low fly ash content (<500 kg/m3), and the optimal recipe based on fly ash in the amount of 600 kg/m3 was indicated.

Effect of using Fly Ash and Attapulgite Lightweight Aggregates on Some Properties of Concrete

Effect of using Fly Ash and Attapulgite Lightweight Aggregates on Some Properties of Concrete

A novel use of incineration bottom ash for H2 aeration in the production of artificial lightweight aggregates

Cold bonding is an energy-efficient method for producing artificial aggregate (AA). However, the relatively high density of AA restricts its use in lightweight concrete products. This study aims to fully upcycle aluminum (Al) content in municipal solid waste incineration bottom ash (IBA) for H2 aeration in the production of lightweight artificial aggregate through alkali activation. To achieve this, the glass particles (GP) in IBA were ground into powder and used as the precursor for NaOH, while the remaining IBA (RIBA), rich in Al, served as the foaming agent. The results showed that RIBA particles (<300 μm) can be used to produce lightweight AA with a loose bulk density ranging from 780 to 840 kg/m3, comparable to sintered fly ash aggregates, and a wide pore size distribution ranging from 0.02 mm to over 1 mm. The inclusion of finer RIBA particles (<75 μm) enhanced the homogeneity of the pore structure, resulting in aggregate strengths of 0.4–0.6 MPa. Moreover, increasing the GP content in IBA up to 40% further boosted the aggregate strength to 1.1 MPa by refining the pore structure and promoting more (C)-N-A-S-H gels with Q4 structures. To ensure sufficient geopolymerization reactions and achieve high strength in the AAs, the alkali concentration should be kept above 3 mol/L. The proposed strategy for lightweight AA production reduced the global warming potential by about 20% compared to the conventional sintered method, offering a more environmentally friendly approach.

Evaluation of geotechnical, mineralogical and environmental properties of clayey soil stabilized with different industrial by-products: A comparative study

The utilisation of soil stabilization techniques employing binders like lime or cement enables the use of soils that are classified as disposable, thereby reducing the need for landfills and the consumption of natural resources. However, the production of lime and cement results in significant CO2 emissions. Therefore, the application of industrial by-products (IBP) for stabilizing expansive soils presents an opportunity to minimise the use of traditional binders. This study investigates the geotechnical, mechanical, mineralogical, and environmental properties of four IBP (biomass bottom ash, biomass fly ash, steel slag, and mixed recycled aggregate) combined with a silica-based nanomaterial for road layer applications. The technical feasibility of the use of IBP was demonstrated, especially in combination with nanomaterials, allowing a 66 % reduction in the percentage of added lime, obtaining significant improvements with minimal plasticity and swelling index and bearing capacity CBR values higher than 25 %, applying BBA, BFA and SS. An environmental assessment of leachate analysis was performance, showing an immobilization of heavy metals that makes the application of IBP feasible. In addition, a life cycle analysis study showed the environmental benefits of applying IBP, such as a 50 % reduction in CO2 emissions due to the reduction of lime, resulting from the use of these materials, thus promoting more sustainable economic models.

Study on the mechanical properties, thermal properties, and microstructure of phase change concrete (PCC): The application of active frost resistance of concrete in frozen soil areas

This paper addresses the issue of freezing damage to concrete structures in regions with frozen soil and overcomes the limitations of traditional frost resistance enhancement methods by integrating both active and passive frost resistance strategies. A novel low-temperature phase change concrete (PCC) is developed using specially designed phase change aggregates and fly ash to replace gravel and cement, respectively. Macroscopic mechanical tests are employed to investigate the evolution of the mechanical properties of PCC. The temperature control capabilities of PCC are quantitatively assessed through thermal physical parameters, heat storage and release curves, and infrared thermal imaging, alongside the introduction of a temperature damping indicator to elucidate the mechanisms underlying active frost resistance enhancement. Furthermore, XRD NMR, and SEM are utilized to further explore the influence of fly ash and phase change aggregates on the microstructural characteristics of PCC. The results show that the addition of phase change aggregates can reduce the strength, porosity, and ductility of concrete. The PCC prepared by mixing phase change aggregates with fly ash demonstrates effective temperature control performance while maintaining satisfactory mechanical properties. The noticeable temperature plateau around 0 °C in the heat storage and release curve, along with the multi-layered annular flare distribution observed in infrared thermal imaging, suggests that the temperature damping effect significantly mitigates the freeze-thaw impact experienced by PCC. Overall, the A-8 sample, with 20 % phase change aggregate and 30 % fly ash added, exhibits the most favorable comprehensive performance, showing reductions of 2.63 %, 39.57 %, and 33.04 % in uniaxial compressive strength, porosity, and maximum temperature difference, respectively, compared to the control group, along with a 75.62 % increase in relative temperature damping.

Enhancing Sustainable Concrete Production by Utilizing Fly Ash and Recycled Concrete Aggregate with Experimental Investigation and Machine Learning Modeling

Enhancing Sustainable Concrete Production by Utilizing Fly Ash and Recycled Concrete Aggregate with Experimental Investigation and Machine Learning Modeling

Optimization and Evaluation of Alkali Activated Fly Ash for Lightweight Aggregate Production

This study investigates the utilization of solid waste, specifically fly ash, and other materials to produce aggregates through geopolymerisation. The research aims to explore the properties of fly ash aggregates and assess their viability in concrete production. The objectives of the study encompass the preparation of aggregates using different proportions of fly ash and alkali activator such as sodium hydroxide and sodium silicate, alongside the casting of concrete cubes utilizing the artificial aggregate. The methodology employed involves the preparation of alkali activator, mix proportioning, and the subsequent processes of mixing, casting, crushing, and curing. Various ratios of fly ash to activator (2.5:1, 3:1, and 3.5:1) were investigated, with corresponding results obtained for properties such as abrasion value, impact value, bulk specific gravity, and water absorption. The findings reveal that the properties of the fly ash aggregates vary with different ratios, with notable differences observed in abrasion value, impact value, bulk specific gravity, and water absorption. For 2.5:1 abrasion value is 26.02%, impact value is 19.32%, bulk specific gravity 1.821 and water absorption 9.61%.For 3:1 abrasion value is 37.14%, impact value is 25.15%, bulk specific gravity 1.78 and water absorption 10.58%.For 3.5:1 abrasion value is 46.5%, imapct value is 32.87%, bulk specific gravity 1.648 and water absorption 12.83%. Casting cude using ratio 2.5:1, 28 day strength is 20.46 N/mm2.. This research project offers an eco-friendly solution for utilizing fly ash in the production of high-performance aggregates, contributing to sustainable construction practices. The implications of the findings include reduced environmental impact, enhanced resource efficiency, and the potential for resilient and environmentally conscious built environments. Further research and development in this area could lead to broader adoption of geopolymerized fly ash aggregates in the construction industry, paving the way for a more sustainable and Greener future.

Assessing the Impact of Fly Ash and Recycled Concrete Aggregates on Fibre-Reinforced Self-Compacting Concrete Strength and Durability

Driven by the insatiable demand for construction materials, excessive quarrying for natural aggregates and the demand for raw materials for cement production pose significant environmental challenges, including habitat loss and resource depletion. To address these concerns, this study investigates the use of fibre-reinforced self-compacting concrete (FR-SCC) with high-volume fly ash (HVFA) and varying levels of recycled concrete aggregates (RCA) as substitutes for fine and coarse aggregates. This approach aims to simultaneously address environmental concerns by reducing reliance on virgin resources by utilizing the recycled aggregates and enhancing the performance of concrete through the combined benefits of fly ash and fibre reinforcement. In this study, Self-Compacting Concrete (SCC) mixes were created with 50% of fly ash replaced with conventional cement content, which was taken from the previous literature. Fine and coarse aggregate utilized in this investigation were replaced with processed recycled aggregates at varying levels from 0% to 100% at an interval of 25%, offering a promising solution to alleviate the environmental burden associated with excessive quarrying while contributing to sustainable construction practices. Additionally, replacement levels of aggregate synthetic polypropylene fibres (PF) were added into the concrete matrix up to 1% at an interval of 0.25%. This research contributes to the development of sustainable construction practices by promoting resource efficiency and minimizing environmental impact. The study found that SCC mixes with fibres and recycled aggregates maintained self-compactability, with polypropylene fibres and fly ash improving workability and cohesion. With this combination of materials, the highest strength value of 55.31 MPa was observed and the study promotes sustainable construction by reducing reliance on virgin resources and minimizing environmental impact.

Enhancing Sustainability in Construction: An Evaluation of Lightweight Concrete with Sintered Fly Ash and Waste Marble Sand

Abstract Marble waste and fly ash are industrial waste, and disposal of these wastes is a big challenge for environmental sustainability. In this study, we explore an innovative approach to sustainable construction by utilizing industrial by-products: sintered fly ash aggregate (SFA) and waste marble sand in lightweight aggregate concrete (LWAC). This study used SFA as a coarse aggregate, whereas river sand was partially replaced by waste marble sand (10–50 %). The waste marble sand modified LWAC has been investigated for mechanical and durability properties. The test related to permeability like water absorption, sorptivity, permeability, and drying shrinkage has been performed. Mercury intrusion porosimetry test was performed to validate durability results. The results indicate that 30 % of river sand can be replaced with waste marble sand as it improves the overall performance of LWAC. Our research contributes to global sustainability efforts by providing a method to reduce industrial waste through its incorporation in building materials. This study not only addresses the urgent need for environmental preservation but also offers potential enhancements in the mechanical properties of LWAC, making it a viable and eco-friendly option in the construction industry worldwide.

Development and Mechanical Performance of Self-Compacting Lightweight Aggregate Concrete Using Sintered Fly Ash Aggregates

Development and Mechanical Performance of Self-Compacting Lightweight Aggregate Concrete Using Sintered Fly Ash Aggregates

The influence of measurement conditions on the determined values of thermal parameters of different types of concrete

In recent years, great emphasis has been placed on the introduction of energy-saving solutions to the construction sector. Building envelopes made of concrete with a specially selected composition give great opportunities in this regard. As part of a wide-ranging experiment, the authors undertook to diagnose how much thermal conductivity, volumetric specific heat and thermal diffusivity can be improved with an aerating admixture and different types of aggregates. Three groups of composites were tested: B1 – on stone aggregate, B2 – on expanded clay aggregate, B3 – on sintered fly ash aggregate. Each of the groups was divided into 4 formulations made without an aerating admixture and with its increasingly higher content of 0.8, 1.1, 1.4% in relation to the weight of cement. The thermal parameters were measured on the top (T) and bottom (B) surfaces of 36 rectangular samples (3 samples from each of the 12 mixtures) with the ISOMET 2104 apparatus. Diagnostic tests concerning the influence of measurement conditions were carried out on dry and water-saturated samples. It has been proven that for each composite and in both conditions, the values of thermal parameters determined on the lower surfaces will not correctly describe the properties of the real structure present in the main volume of the element. Only measurements carried out on surfaces with a structure corresponding to the interior of the element provide adequate data that can be used in decision-making processes and in numerical simulations to assess the real thermal qualities of building envelopes.

Prediction of compressive strength of high-volume fly ash self-compacting concrete with silica fume using machine learning techniques

The quality and composition of the components in Self-Compacting Concrete (SCC) determine its compressive strength; however, determining these complex relationships through traditional statistical methods is difficult. This study uses five state-of-the-art machine learning techniques, namely, Random Forest (RF), Adaboost, Convolutional Neural Network (CNN), K-Nearest Neighbor (KNN), and Bidirectional Long Short-Term Memory (BI-LSTM), to simulate the strength properties of high-volume fly ash self-compacting concrete (HVFA-SCC) with silica fume. A database with 240 SCC compressive strength tests that included a range of material proportions was put together in order to train these models. The primary constituents that were selected and taken into consideration as input variables were cement, fly ash, super-plasticizer, silica fume, coarse and fine aggregate, and age. Various statistical metrics, regression error characteristics curve, SHAP analysis, and uncertainty analysis were used to validate the models' effectiveness in predicting the compressive strength of HVFA-SCC with varying material compositions. The recommended RF model demonstrated the highest predictive accuracy of all the models that were analysed. While machine learning can predict compressive strengths, its opaque 'black-box' nature limits its use for SCC mix engineers. This study introduces an open-source Random Forest-based GUI to close this gap. This interface helps engineers make mix proportion decisions by accurately estimating SCC compressive strength under various test conditions.

Effects of aircraft operating fluids and environmental thermal fatigue on fly ash and steel slag based cementitious composites

This paper investigates the performance of concrete incorporating high-volume fly ash (HVFA) and steel slag aggregates against the detrimental effects of combined cycles of environmental thermal fatigue and exposure to leaked aircraft fluids. A total of 128 cubes and 90 prisms were cast for five mixes and exposed to 60, 120, 180, 240 and 300 combined cycles. The results demonstrate the positive effect of utilization of HVFA which reduces the total amount of portlandite available in the system. The SS aggregates demonstrate a strong interlocking with the surrounding matrix and supply the necessary portlandite for continued pozzolanic reaction. However, their reaction with aircraft fluids causes significant degradation to flexural strength initially, which is redeemed by pozzolanic reaction at a later stage. Hybrid basalt and polypropylene fibres were successful in enhancing the flexural strength and reducing the cracking. The mercury intrusion porosimetry revealed a reduction in pore volume because of HVFA. Scanning electron microscopy and differential scanning calorimetry were also employed to uncover the underlying mechanisms of damage and assess the performance of the cementitious composite.

Developing geopolymer concrete using fine recycled concrete powder and recycled aggregates

To develop a sustainable geopolymer concrete (GC), the efficacy of using fine recycled concrete powder (FRCP) and recycled aggregates (RA) as partial replacements for fly ash (FA) and natural aggregates (NA), respectively, was investigated. The compressive strengths of different GCs were measured. The durability performance was assessed by means of capillary suction tests, initial surface absorption tests and acid attack performed at ambient curing. The compressive strength of the GC made with 50% RA (both coarse and fine) and FRCP was found to be comparable to that of GC made with NA. Similarly, the inclusion of FRCP in the GC mixes resulted in a pore-blocking effect, restricting water ingress to the GC through capillary suction and surface absorption, even with the use of 50% coarse RA and 25% fine RA. The results demonstrated that sustainable GC can be developed using appropriate doses of FRCP and RA.

Mix design of FA-GGBS based lightweight geopolymer concrete incorporating sintered fly ash aggregate as coarse aggregate

Geopolymer concrete (GPC) is emerging as a sustainable alternative to conventional Portland cement-based concrete due to its significantly reduced carbon footprint and enhanced durability. To mitigate the environmental hazard posed by the disposal of fly ash (FA) and ground granulated blast furnace slag (GGBS) waste and reduce cement consumption, effective promotion of the geopolymerization technique is necessary. Incorporating sintered fly ash coarse aggregate (SFA) in GPC makes the concrete light in weight. This study involves the synthesis of geopolymer technology using FA and GGBS, as the primary source material. Due to the lack of an appropriate mix design method for using SFA in GPC, their application as a structural concrete is scanty. By using FA and GGBS with 100% SFA, a novel mix design methodology that offers greater simplicity and consistency is established in the present study. The proposed method is further verified by developing different concretes with alkali content to binder (AC/B) ratios ranging from 0.3 to 0.8. Fresh densities range between 1860 and 1930 kg/m3 and maximum compressive strength of nearly 50 MPa was attained after 28 days of ambient curing. The binder penetration and internal curing in SFA indicate that GGBS and FA have a superior synergistic effect on the efficacy of lightweight GPC using SFA.

Study on Sorptivity Test on Fly Ash Aggregate Concrete

Aggregate is most widely used in reinforced concrete construction. In this investigation, fly ash aggregates were used in concrete and its effect on durability of concrete was studied. The fly ash was collected from Mettur Thermal Power plant. Then the cement fly ash proportion of 10:90, 12.5:87.5, 15:85, 17.5:82.5, 20:80 and 22.5:77.5 were adopted to get fly ash aggregates. The Particle size distribution, Specific gravity and Water absorption tests on aggregates were conducted. M20 grade of concrete was considered. The fresh concrete tests like Slump test and Compacting factor test were conducted. For the plain concrete and fly ash aggregate concrete the cubes were cast. All the specimens were cured in a curing tank. The plain and fly ash aggregate concrete cube specimens were cast and tested at the age of 28days and 56days. Sorptivity and saturated water absorption tests were conducted on these plain and fly ash aggregate concrete specimens. The results were tabulated and compared by drawing graphs. Based on the results obtained, conclusions and suggestions were made.

Experimental Investigation on Ductility in Fly Ash Aggregate Concrete

Aggregate in concrete is structural filler, which occupies the most of the volume of the concrete The composition, shape and size of the aggregate have significant impact on the workability, durability, strength, weight and shrinkage of the concrete. In recent period some of the aggregates are chemically active and also that certain aggregates exhibit chemical bond at the interface of aggregate and paste. Aggregate occupy 60-80% of the volume of concrete is considerable. The utilization of fly ash in concrete as partial replacement of cement is gaining immense importance today, mainly on account of the improvement in the long term durability of concrete combined with ecological benefits. Three grades of ordinary Portland cement (OPC) are 33,43 and 53 as classified by Bureau of Indian Standard (BIS) are commonly used in construction industry. The main variable investigated in this study is variation of fly ash dosage in 10%, 20%, 30% and 40%. The compressive strength, durability and shrinkage of concrete were mainly studied. The fly ash is collected in Mettur Thermal Power Plant. Then the cement and fly ash proportions of 12.5:87.5, 15:85 and 17.5:82.5 will be adopted to get fly ash aggregates. The particle size distribution, specific gravity, bulk density, impact test on aggregate will be conducted. For the plain concrete and fly ash aggregate concrete of beams (Plain concrete and RCC beams), cubes and cylinders will be cast. All the specimens will be cured in a curing tank. The Ductility test and compressive strength test will be conducted on these plain and fly ash aggregate concrete specimens.

Evolutionary Algorithms for Strength Prediction of Geopolymer Concrete

Geopolymer concrete (GPC) serves as a sustainable substitute for conventional concrete by employing alternative cementitious materials such as fly ash (FA) instead of ordinary Portland cement (OPC), contributing to environmental and durability benefits. To increase the rate of utilization of FA in the construction industry, distinctive characteristics of two machine learning (ML) methods, namely, gene expression programming (GEP) and multi-expression programming (MEP), were utilized in this study to propose precise prediction models for the compressive strength and split tensile strength of GPC comprising FA as a binder. A comprehensive database was collated, which comprised 301 compressive strength and 96 split tensile strength results. Seven distinct input variables were employed for the modeling purpose, i.e., FA, sodium hydroxide, sodium silicate, water, superplasticizer, and fine and coarse aggregates contents. The performance of the developed models was assessed via numerous statistical metrics and absolute error plots. In addition, a parametric analysis of the finalized models was performed to validate the prediction ability and accuracy of the finalized models. The GEP-based prediction models exhibited better performance, accuracy, and generalization capability compared with the MEP-based models in this study. The GEP-based models demonstrated higher correlation coefficients (R) for predicting the compressive and split tensile strengths, with the values of 0.89 and 0.87, respectively, compared with the MEP-based models, which yielded the R values of 0.76 and 0.73, respectively. The mean absolute errors for the GEP- and MEP-based models for predicting the compressive strength were 5.09 MPa and 6.78 MPa, respectively, while those for the split tensile strengths were 0.42 MPa and 0.51 MPa, respectively. The finalized models offered simple mathematical formulations using the GEP and Python code-based formulations from MEP for predicting the compressive and tensile strengths of GPC. The developed models indicated practical application potential in optimizing geopolymer mix designs. This research work contributes to the ongoing efforts in advancing ML applications in the construction industry, highlighting the importance of sustainable materials for the future.

A year-long study of eco-friendly fibre reinforced cementitious composites with high volume fly ash and industrial waste aggregates

A year-long study of eco-friendly fibre reinforced cementitious composites with high volume fly ash and industrial waste aggregates

Enhancing Structural Performance: Fiber Reinforcement in Sintered Flyash Lightweight Concrete for Impact Resistance and Toughness

Objectives: The goal of this project is to better understand the interaction between fibers and concrete in order to produce Light Weight Aggregate Concrete (LWAC) with improved structural performance that is made from recycled materials, such as sintered flyash aggregate, and LWAC structures that are more resistant to impact loads and other dynamic forces. Methods: The sintered flyash aggregates are added as coarse aggregate to the concrete and basalt fiber (0.25% of mix) is used as a secondary reinforcement to improve the energy absorption, impact resistance and toughness behaviour. M30 grade of concrete was arrived after laboratory trials after which the mechanical properties were evaluated. The effect of drop impact load on slabs of size 300mm x 300mm x 50mm reinforced with two layers of bundled wire mesh was studied. The flexural properties of concrete reinforced with fiber prism of size 500mm x 100mm x 100mm were evaluated. Findings: With the addition of fiber, flexural toughness index and post-cracking toughness were increased notably on the initial deflections and cracks. The conventional fiber reinforced concrete exhibited a superior peak load capacity compared to normal weight concrete, with a measured increase of 7.5%. Conversely, normal-weight concrete demonstrated a significantly higher deflection under load, exceeding that of fiber reinforced concrete by 47%. LWAC displayed a distinct increase in both peak load (18.7%) and deflection (39.13%) when compared to Normal Weight Aggregate Concrete (NWAC). The incorporation of basalt fiber enhanced the energy absorption by 150% in NWAC and 80% in LWAC. Novelty: The incorporation of fiber into lightweight concrete reduces the brittle nature of failure. The post-cracking toughness behaviour was enhanced because of the effect of crack-arresting by fibers. After the first break, it was discovered to retain residual strength, and removing the fibers from the matrix required more force. Keywords: Sintered flyash aggregate, Light weight concrete, Basalt fiber, Toughness, Impact load, Energy absorption