High Volume Fly Ash Research Articles

Engineered Cementitious Composite with Nanocellulose and High-Volume Fly Ash

This research develops a sustainable Engineered Cementitious Composites (ECC) with reduced cement usage by incorporating high volume fly ash (HVFA) and silica fume, along with the novel application of nanocellulose (NC), a plant-based nanomaterial, and hybrid fibres to achieve high strength and ductility simultaneously. 12 mixes were developed including three base ECC mixes with 1.5% polyethylene (PE) and 0.5% steel fibres with varying proportions of fly ash and silica fume (1.2:0-1:0.2) and nine NC reinforced ECC mixes with varying dosages of NC (0.15%, 0.2%, 0.25% by weight). The effect of fly ash/silica fume ratio and NC on mechanical properties was investigated through compressive and uniaxial tensile tests. Scanning electron microscope (SEM) and differential scanning calorimetry (DSC) techniques were utilized to gain insights into the HVFA and NC matrix systems and NC and hybrid fibre mechanism. Results showed that reducing the fly ash/ silica fume ratio increased strength but reduced tensile strain. Incorporating NC improved strength across all mixes, irrespective of fly ash/silica fume content, with the mix containing 0.2% NC showing the highest improvement. This novel ECC is anticipated to offer a sustainable and high-performance material solution for engineering structures.

Strength and Microstructural Characteristics of Activated Fly Ash–Cement Paste

Incorporating high volumes of fly ash (FA) in filling materials reduces costs and carbon emissions, but low early strength limits its use. This study investigates the effects of sodium sulfate decahydrate (Na2SO4·10H2O) and calcium hydroxide (Ca(OH)2) as activators at concentrations of 0.5%, 1.0%, 1.5%, and 2.0% on the mechanical properties and microstructure of tailings–cement–fly ash composites. Compressive strength testing, X-ray diffraction (XRD), and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) were used to evaluate performance at different curing stages. Results indicate that all activators enhance early strength, with 2.0% Ca(OH)2 yielding the greatest improvement. Microstructural analysis showed that activators boost quartz reactivity and create denser structures. Na2SO4 promotes ettringite and gypsum formation, while Ca(OH)2 increases alkalinity, enhancing gel formation from FA. These findings clarify how activators improve the performance of activated fly ash–cement paste (AFCP).

A Review on the Mechanical Performance of High-Volume Fly Ash Light-Weight Concrete

A Review on the Mechanical Performance of High-Volume Fly Ash Light-Weight Concrete

Strategies for Developing High-Volume Fly Ash Concrete with High Early-Age Strength for Precast Applications

Strategies for Developing High-Volume Fly Ash Concrete with High Early-Age Strength for Precast Applications

Feasibility study of utilizing Autoclaved Aerated Concrete (AAC) waste for the production of cold bonded lightweight artificial aggregate using high volume fly ash (HVFA) binders

Autoclaved Aerated Concrete (AAC) is a popular construction material used for partitions and insulation in buildings. At the end of its service life, AAC (Autoclaved Aerated Concrete) will be demolished and subsequently disposed of in landfills, thereby creating depository problem. Therefore, the study of reutilization and recycling of AAC waste is imperative. Artificial aggregate production can be an alternative to the reutilization of AAC waste. This paper assesses the feasibility of using Autoclaved Aerated Concrete Powder (AACP) waste as a raw material for the production of artificial aggregate and investigate its physico-mechanical properties. The investigation incorporates the comparison of cement-based binder with high-volume fly ash (HVFA) binder with different replacement levels of cement. The study uses image analysis based on photographic, optical microscopic, and scanning electron microscopy (SEM) images, to describe the porosity of the aggregate. The results show that the AACP aggregates with both cement and HVFA binders meets the current industry requirement for density and cylinder crushing strength as lightweight artificial aggregate. The appropriate binder content lies between 30 % and 40 %. The best cement to fly ash ratio in HVFA binder is determined to be of 1:1 with 50 % replacement of cement with fly ash. Image analysis showed that the porosity largely affected the properties of the AACP aggregate such as density and water absorption. However, further investigation into the reducing high-water absorption of AACP aggregates is necessary to improve their overall quality.

Hydration and Mechanical Properties of High-Volume Fly Ash Cement under Different Curing Temperatures.

This study aimed to investigate the effects of different curing temperatures on the hydration and mechanical properties of high-volume fly ash (HVFA) concrete. The key variables were curing temperature (13 °C, 23 °C, 43 °C) and fly ash (FA) content (0%, 35%, 55%). The hydration characteristics of HVFA cement were examined by evaluating the setting time and heat of hydration under different curing temperatures. The mechanical properties of HVFA concrete were analyzed by preparing concrete specimens at various curing temperatures and measuring the compressive strength at 7, 28, 56, and 91 days. The results indicated that concrete with high FA content was more sensitive to curing temperature compared to ordinary Portland cement.

Improvement of properties of high volume fly ash based self-compacting mortar with dolomite and ground granulated blast furnace slag

Usage of filler with inert or pozzolanic property has been crucially required for fabricating the practicalself-compacting mortar or self-compacting concrete. The current study investigates the influence of usingthe dolomite powder on the enhanced properties of the high volume Class F fly ash self-compacting mortarwith/without addition of ground granulated blast furnace slag (GGBFS/slag). Experimental results showed thatpartial replacement of low calcium Class F fly ash with the dolomite powder not only increased the workability of the fresh modified self-compacting mortars but also enhanced the ordinary Portland cement hydrationprocess at early. The adjustment of dolomite powder addition as partial replacement of fly ash resulted in themodified self-compacting mortars with the compressive strength increased after 7 days of curing. 30 masspercent of dolomite powder partially replacing fly ash was considered as the optimum value to induce the hardened modified self-compacting mortars with the compressive strengths increased at 4.2, 10.4, and 10.5% at3, 7, and 28 days, respectively. With the content of dolomite powder being fixed at 30 and 50 mass percent,partial replacement of fly ash with slag at 50 mass percent induced the modified self-compacting mortars withsignificant enhancement of the engineering properties.

Shrinkage and Creep Properties of Low-Carbon Hybrid Cement.

Hybrid cements combine clinker with large amount of supplementary cementitious materials while utilizing hydration and alkali activation processes. This paper summarizes shrinkage and creep properties of industrially produced H-cement, containing only 20% of Portland clinker. In comparison with a reference cement CEM II/B-S 32.5 R, autogenous shrinkage is smaller after 7 days, and drying shrinkage is similar at similar times. A different capillary system of H-cement leads to faster water mass loss during drying. Basic and total creep of concrete remains in the standard deviation of B4 and EC2 creep models. The results demonstrate that shrinkage and creep properties of concrete made from H-cement have similar behavior as conventional structural concrete or high-volume fly ash concrete.

A Case Study of Concrete Incorporating High Volume Fly Ash and Bottom Ash for Sustainable Housing

A Case Study of Concrete Incorporating High Volume Fly Ash and Bottom Ash for Sustainable Housing

Enhancing Compressive Strength of Very High Volume Fly Ash Concrete Using Low Molarity Alkali Solution and Thermal Activation

Enhancing Compressive Strength of Very High Volume Fly Ash Concrete Using Low Molarity Alkali Solution and Thermal Activation

Geotechnical and microstructural analysis of high-volume fly ash stabilized clayey soil and machine learning application

The weak soil stabilization using solid wastes is one of the most common solutions for improving geotechnical characteristics as well as for problematic waste dumping in landfills. The present experimental study aims to examine the effect of high-volume Class-F fly ash on the geotechnical and microstructural properties of clayey soil by adding them in ranges between 5 % and 50 %. The results show that as the amount of fly ash in clayey soil increases, properties like the specific gravity, plasticity index, permeability, optimum moisture content, maximum dry density and free swelling index improves. Moreover, these geotechnical properties were analyzed to develop machine learning models using three different algorithms, namely K-nearest neighbor regression, random forest, and support vector regression, for obtaining the optimum amount of fly ash contents in weak expansive soils. The predicted and experimental results found to be in close-relation for predicting the geotechnical behavior of modified clayey soil. Furthermore, the performance of the ML models degrades as the number of components reduces, with KNN regression consistently outperforming SVR and RF but suffering significantly with fewer components. The results of the testing set in the case of four components are MSE of 77, R² of 0.896, RMSE of 0.846, MAE of 0.327, and SEE of 0.858, indicating precise and consistent predictions. However, the prediction accuracy considering lesser components shows MSE as 262, R² as 0.648, MAE as 5.606, SEE as 16.707, and GPI as 1.056, confirming the elevated error rates. Overall, it has been concluded that combining comprehensive experimental work and machine learning techniques outperforms in enhancing geotechnical data processing, optimized waste contents in weak soils, improves sustainability in construction, saves resources, reduces the possibility of human mistakes, and increases reliability.

The effect of high-volume intraoperative fluid administration on outcomes among pediatric patients undergoing living donor liver transplantation

BackgroundPediatric patients undergoing liver transplantation are particularly susceptible to complications arising from intraoperative fluid management strategies. Conventional liberal fluid administration has been challenged due to its association with increased perioperative morbidity. This study aimed to assess the impact of intraoperative high-volume fluid therapy on pediatric patients who are undergoing living donor liver transplantation (LDLT).MethodsConducted at the Children’s Hospital of Chongqing Medical University from March 2018 to April 2021, this retrospective study involved 90 pediatric patients divided into high-volume and non-high-volume fluid administration groups based on the 80th percentile of fluid administered. We collected the perioperative parameters and postoperative information of two groups. Multivariable logistic regression was utilized to assess the association between estimated blood loss (EBL) and high-volume FA. Kaplan-Meier survival analysis was used to compare patient survival after pediatric LDLT.ResultsPatients in the high-volume FA group received a higher EBL and longer length of stay than that in the non-high-volume FA group. Multivariate logistic regression analysis indicated that hours of maintenance fluids and fresh frozen plasma were significantly associated risk factors for the occurrence of EBL during pediatric LDLT. In addition, survival analysis showed no significant differences in one-year mortality between the groups.ConclusionsHigh-volume fluid administration during LDLT is linked with poorer intraoperative and postoperative outcomes among pediatric patients. These findings underscore the need for more conservative fluid management strategies in pediatric liver transplantations to enhance recovery and reduce complications.

Effect of Microwave Curing on the Performance of High-volume Fly Ash Concrete

Concrete curing significantly impacts mechanical properties and durability, yet traditional methods face efficiency challenges. Microwave curing (MC) offers a promising alternative, providing rapid and uniform concrete curing. However, fully understanding the impact of MC on concrete performance, particularly in high-volume fly ash concrete (HVFC), remains a research gap. This study addresses this gap by investigating the effect of MC on key properties of HVFC, including compressive strength, drying shrinkage, chloride ion penetration, and resistance to sulfate attack. Concrete specimens underwent MC at varied energies (200–1000 W) and durations (10–30 min) to evaluate their mechanical and durability characteristics. Results show that MC significantly boosts early-stage concrete strength, notably at high applied energy. The specimen cured at 1000 W for 30 min (MC1000-30) achieved the highest 1-day strength of 23.68 MPa. However, the normal curing specimen exhibited the highest strength of 32.07 MPa at 28 days while the strength value of the MC1000-30 specimen declined to 20.25 MPa, indicating a 36.85% decrease. Although declining strength was observed after 28 days, the MC1000-30 specimen demonstrated improved durability with significantly reduced drying shrinkage (by 83.12%) and chloride ion penetration (by 31.6%). The study underscores the feasibility of utilizing MC for HVFC as it demonstrated significant enhancements in both early-stage concrete strength and durability at a later stage. Careful parameter optimization can ensure sustained effectiveness over time, offering a viable alternative to traditional curing methods.

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.

Development of hybrid gradient boosting models for predicting the compressive strength of high-volume fly ash self-compacting concrete with silica fume

In an effort to extend the service life of structures under harsh exposure conditions and reduce the carbon dioxide emissions from cement production, researchers are examining the performance of cement concretes with different mineral admixtures. This study focuses on self-compacting concrete (SCC) incorporating high-volume fly ash (HVFA) and silica fume (SF) as supplementary cementitious materials (SCMs). The aim is to investigate the fresh and hardened properties, particularly the compressive strength, of these combinations. SCMs were used to replace varying amounts of cement, with SF showing the greatest improvement in mechanical characteristics across all age groups. Advanced modelling techniques, including Gradient Boosting (GB), Gradient Boosting-Particle Swarm Optimization, Gradient Boosting-Bayesian Optimization, and Gradient Boosting-Differential Evolution (GB-DE), were employed to analyse the strength characteristics of HVFA-SCC. The GB-DE model emerged as the most accurate, with an R² value of 0.995029 and an RMSE of 0.023862. Additionally, an open-source GUI based on GB-DE is introduced to provide engineers with a transparent tool for optimizing concrete mix designs, addressing the opacity of traditional machine learning models.

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.

Enhancing the resistance of cementitious composites to environmental thermal fatigue using high-volume fly ash and steel slag

Daily fluctuations in environmental temperature induce thermal fatigue and cause degradation in concrete structures. This study introduces a novel approach of utilizing high-volume fly ash, steel slag fine aggregates, and basalt-polypropylene fibres to prevent degradation against environmental thermal fatigue (ETF). Five mixes were considered with variations in fine aggregate type, fibre length and volume. The compressive and flexural strengths were analysed after exposure to 60, 120, 180, 240, and 300 ETF cycles between 20 and 60 °C (at constant relative humidity). The residual compressive strength of mix with 100 % river sand and 100 % steel slag as fine aggregates was ∼106 % and ∼112 % respectively after 300 ETF cycles. The developed cementitious composites performed significantly better than the mixes utilized in the existing literature. The mix with 100 % steel slag aggregate even demonstrated a continual rise in compressive strength as opposed to mixes with river sand whose strength declined after 180 or 240 ETF cycles. Flexural strength also improved up to 180 ETF cycles and then started to decline in all mixes. A thorough microstructural analysis was also conducted using scanning electron microscopy, differential scanning calorimetry, and mercury intrusion porosimetry to gain further insights into the underlying mechanism of the newly introduced matrix composition against ETF.

Development of ANN-based metaheuristic models for the study of the durability characteristics of high-volume fly ash self-compacting concrete with silica fume

The construction of durable and sustainable infrastructure requires the use of industrial byproducts such as fly ash (FA) and silica fume (SF) to enhance strength and durability. This study introduces novel machine learning models to forecast the results of rapid chloride penetration test (RCPT) for self-compacting concrete (SCC) containing high volumes of FA and SF. This study assessed the effects of supplementary cementitious materials (SCMs) and elevated temperature curing on the RCPT outcomes for SCC. Various metaheuristic algorithms including teaching–learning-based optimization (TLBO), ant colony optimization (ACO), the imperialist competitive algorithm (ICA), and shuffled complex evolution (SCE)—optimize the learning rate, weights, and biases of artificial neural network (ANN) models. A dataset of 360 experimental RCPT data points with seven input parameters was used to train and test the hybrid models. The accuracy of these models was assessed using eight performance indices, and the results were further analyzed through rank analysis, scatter plots, and error matrices. The training and testing sets for the AI models, specifically ANN-TLBO, exhibit a strong correlation between the experimental and predicted RCPT values, with R2 values of 0.9962 for training and 0.9676 for testing, compared to the R2 values of the other proposed models. Consequently, the results of this study suggest that the ANN-TLBO model is the optimal hybrid ANN model for predicting RCPT values in SCC. Verified experimental results and external validation indicate that the ANN-TLBO model is an effective alternative for accurately predicting real-time RCPT in SCC.

Age-dependent deflection analysis of high-volume fly ash RC beams: experimental and artificial neural network modelling

This research examines the influence of high-volume fly ash (HVFA) on reinforced concrete (RC) beam deflections over 180 days of continuous loading. The study comprises eight fly ash-based concrete mixes with varying fly ash ratios (0–60%). Experimental assessments were conducted on two load levels, corresponding to 25% and 50% of the initial cracking load. Thirty-two full-scale RC beams, each measuring 100 × 150 × 1800 mm, were fabricated for both load levels. Long-term deflections were monitored for all concrete mixes through sustained four-point bending tests at ages ranging from 1 to 180 days. A comparative analysis of the overall mid-span deflection between conventional and fly ash concrete RC beams was carried out against established design codes. It was determined that high-volume fly ash RC beams exhibited less creep and shrinkage deflection compared with conventional RC beams. Moreover, artificial neural network (ANN) modelling was also carried out to propose a significant model helpful in predicting the total deflection of RC beams containing any fly ash content and at any age of concrete. The present study offers valuable insights for engineers and designers, facilitating the evaluation of age-dependent deflection patterns in RC beams constructed with reinforced high-volume fly ash concrete.

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.