Fly Ash Aggregate Research Articles

ANALYSIS OF FLYASH AGGREGATE BEHAVIOR IN GEOPOLYMER CONCRETE BEAMS USING METHOD OF INITIAL FUNCTIONS (MATHEMATICAL PROGRAMMING)

The stipulated performance of flyash aggregates in geopolymer concrete beams (composite beam) has been explained using the Method of Initial Functions (MIF) via mathematical programming. This research has specifically focused on understanding its strength and durability characteristics. Geopolymer concrete is now being evaluated as a successful alternative in terms of sustainability in the construction sector and has used flyash, an industrial by-product, for several years as a major binder. The major theme adopted in the present research is concentrated on the mechanical and structural behavior of geopolymer concrete beams partially replaced by flyash aggregates for civil engineering applications. The present paper focuses on using the Method of Initial Functions to model and analyze beam behavior subjected to various loading conditions within a strong mathematical programming approach. In the current study, an explanatory analysis of the flexural strength, load-deflection characteristics, and crack opening profile is conducted without constructing a beam specimen by using MIF.

Organic and Inorganic Modifications to Increase the Efficiency in Immobilization of Heavy Metal (Zn) in Cementitious Composites-The Impact of Cement Matrix Pore Network Characteristics.

This research investigated the properties of modified cementitious composites including water purification from heavy metal-zinc. A new method for characterizing the immobilization properties of tested modifiers was established. Several additions had their properties investigated: biochar (BC), active carbon (AC), nanoparticulate silica (NS), copper slag (CS), iron slag (EAFIS), crushed hazelnut shells (CHS), and lightweight sintered fly ash aggregate (LSFAA). The impact of modifiers on the mechanical and rheological properties of cementitious composites was also studied. It was found that considered additions had a significantly different influence over the investigated properties. The addition of crushed hazelnut shells, although determined as an effective immobilization modifier, significantly deteriorated the mechanical performance of the composite as well as its rheological properties. Modification by iron slag allowed for a significant increase in immobilization properties (five-fold compared to the reference series) without a substantial impact on other properties. The negative effect on immobilization efficiency was observed for nanoparticulate silica modification due to its sealing effect on the pore network of the cement matrix. The capillary pore content in the cement matrix was identified as a parameter significantly influencing the immobilization potential of most considered modifications, except biochar and active carbon.

INFLUENCE AND PREDICTION OF SINTERED AGGREGATE SIZE DISTRIBUTION ON THE PERFORMANCE OF LIGHTWEIGHT ALKALI-ACTIVATED CONCRETE

The most effective method for mitigating the adverse environmental impacts of traditional concrete involves substituting cement and natural aggregate with waste and byproduct resources. Utilizing sintered lightweight aggregate (fly ash) in geopolymer concrete emerges as an efficient solution for managing and disposing of significant amounts of fly ash. The influence of sintered aggregate size distribution on the performance of alkali-activated concrete, focusing on compressive strength improvement. The study employs sintered fly ash aggregate (SFA) as coarse aggregate, aiming to optimize packing density through proper particle distribution. The highest compressive strength is achieved with a mix featuring 75% 4-8mm and 25% 8-12mm SFA. Regression-based strength models are developed, exhibiting good alignment with conventional concrete models. Thin section techniques reveal enhanced aggregate-matrix interaction due to the porous structure of SFA. The study emphasizes the potential of SFA in geopolymer concrete for sustainable construction. Lightweight geopolymer concrete, owing to its lower density, significantly reduces the overall structural load.

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

Compressive strength study of fibre reinforced concrete

Abstract Materials play a vital role in the development of human life. Environmental and sustainable development concerns have seriously affected the development and applications of materials. Due to the advancement of rapid growth, it leads to the utilization of more materials, which leads to the depletion of natural materials. So, this leads the researchers to focus on the materials that have less impact on the environment. This study focuses on the compressive strength-based study of M30-grade fiber-reinforced concrete, partially replacing cement with flyash, fine aggregate with cocopeat, and adding coir fiber as a fiber. In recent times, there has been a tremendous increase in the usage of several natural fibers because of their low cost, ease of processing, and environmental friendliness. Due to their availability and eco friendliness, they are used in the development of fiber-reinforced concrete to improve its strength. The experiment entails casting and curing of different concrete mixtures for 3, 7, and 28 days with varying percentages of coconut fiber and cocopeat, 30% replacement of cement with flyash, and performing compressive strength tests in accordance with IS standards. Test results show adding 1% of coir fiber attains more strength in comparison with normal concrete and concrete with partial replacement of cement with fly ash and fine aggregate with cocopeat.

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.