High Volume Fly Ash Concrete Research Articles

Mechanical properties of high-volume fly ash concrete with varying fly ash content

Fly ash is widely used as a replacement for cement to produce more environmentally friendly concrete with reliable performance in construction applications. Therefore, this research aimed to analyze the mechanical properties of high-volume fly ash concrete (HVFAC) using class F fly ash with different percentages. Performance tests that were carried out included workability, unit weight, and compressive strength. Laboratory experiments were conducted by making 5 variations of mix design, namely variation 1 (FA0), which consisted of normal concrete with a control test material of 100% Portland cement. The other 4 variations were HVFAC (FA70, FA80, FA90, and FA100), which were made with fly ash content comprising 70%, 80%, 90%, and 100% of the total binders/cementitious. Fresh concrete was tested for workability, while hardened concrete was tested for unit weight and compressive strength at ages 3, 7, and 28 days on test specimens subjected to water immersion curing. The results showed that all workability of HVFAC test specimens met the self-consolidated concrete (SCC) category. The dry unit weight of all specimens met the requirements for normal-weight concrete. The results of the compressive strength test at 28 days showed that the addition of fly ash percentage caused a decrease in the compressive strength value of the entire HVFAC, but still exceeded the minimum requirements for high-quality concrete. HVFAC with variations FA70, FA80, and FA90 met the requirements of ASTM C618-12a based on the evaluation of Strength Activity Index (SAI) values at 7 and 28 days of age, while FA100 did not meet the requirements.

Multiscale prediction model for autogenous shrinkage of early-age concrete incorporating high volume fly ash

High volume fly ash concrete (HVFAC) manufacture is an effective strategy to mitigate the autogenous shrinkage, achieve green production and low cost in building engineering. Nevertheless, a reasonable and robust multiscale prediction model of autogenous shrinkage of HVFAC and relative input parameters remains lacking. Thus, the objective of present study is to make up the missing gap. The research offered the input parameters dataset of microscopic pore structure, internal relative humidity (IRH) and validation dataset of autogenous shrinkage of cement pates and concretes with a water to binder ratio of 0.30/0.40, with fly ash in cement mass replacing-levels of 0, 30 %, 50 % and 70 %. The multiscale autogenous shrinkage prediction model was established by three parts of bulk modulus homogenization, capillary pressure calculation and composite models. The needed volumetric ratios of multi-phases were obtained by VCCTL software; bulk modulus was homogenized by Mori-Tanaka method, the proposed prediction models of IRH and LF-NMR-based microscopic pores characterization were used for capillary pressure calculation at cement paste level; composite models for autogenous shrinkage transformation from paste level to concrete level. The results show that HVFAC is capable of improved shrinkage-related pore structure, IRH and low autogenous shrinkage, which backs up the application potential of HVFAC in building engineering, and the input parameters dataset is confirmed to be reasonable. The proposed multiscale model was validated to be robust via comparing with test results and references dataset. The achievement of this study bear significance for HVFAC design and application in early-age cracking prevention in building engineering.

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

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.

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.

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

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.

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.

UTILIZATION OF HIGH-VOLUME FLY ASH AS A SUPPLEMENTARY CEMENTITIOUS MATERIAL IN ENVIRONMENTALLY FRIENDLY CONCRETE

Innovations in material technology are expected to reduce the use of commercial cement and replace it with other environmentally friendly materials with the same performance as normal concrete. Aim: This study aim to analyze the mechanical property of High-Volume Fly Ash Concrete (HVFAC) using F class fly ash with different mix percentages. Methodology and Results: The experiment was conducted in laboratory scale. Four variations of test specimens consisted of: 1 variation (F0), which is conventional concrete with 100% Portland cement as control specimen, and three variations of HVFC (F70, F80, and F90), which were made with fly ash content (%) 70, 80, and 90 of total cementitious. Fresh concrete testing to determine workability, while hard concrete testing is done by density and compressive strength tests at the age of 3, 7, and 28 days on specimens that have been treated with the water submerged curing method. Conclusion, significance, and impact of study: All HVFAC specimens fulfill the Self Compacting Concrete (SCC) category. The compressive strength test results at 28 days showed that the addition of fly ash percentage caused a decrease in compressive strength values in all HVFAC variants, but still exceeded the minimum requirements of high and medium quality concrete. All HVFAC variations meet the requirements of ASTM C618-23 based on the evaluation of Strength Activity Index (SAI) values at 7 and 28 days of age. The utilization of 90% fly ash as a cement substitute resulted in an environmentally friendly concrete product based on the concept of cleaner production.

Development of high-volume fly ash concrete with improved interfacial transition zone

The interfacial transition zone (ITZ) is a vulnerable region in concrete, particularly in high-volume fly ash (HVFA) concrete where a significant portion of fly ash particles remain unreacted. In order to improve the ITZ of HVFA concrete, this work introduces a novel approach by targeted employing slag in the ITZ. Slag-modified cement paste was used to coat coarse aggregate, which was further mixed with other materials to cast HVFA concrete. Various parameters during preparing the coated coarse aggregate, such as the water-to-cementitious material ratio of the cement paste, the slag content in cementitious materials, the mass ratio of coarse aggregate to cement paste, the mixing time of coarse aggregate and cement paste, and the drying time after mixing, were investigated to uncover their influence on the porosity of the ITZ in HVFA concrete. By using the optimized values of these variables of 0.35, 3.8%, 3.2, 10 min and 1 h, respectively, it is feasible to achieve ITZ in HVFA concrete characterized by a porosity of 23.6% and refined pore structure, alongside enhanced compressive strength of the concrete.

Numerical simulation of early-age thermal stress of high volume fly ash (HVFA) concrete

This paper numerically studied the effect of fly ash (FA) replacement on early-age thermal stress of concrete. Different FA replacement levels (0%, 20%, 50% and 80%) on the thermal stress and cracking risk of concrete have been considered. Results showed that, due to the FA effect on the reduction of hydration heat, the maximum temperature and corresponding compressive stress during the temperature rise stage were both lowered; meanwhile, the strength of concrete was simultaneously weakened, leading to lower cracking stress when the FA replacement increased gradually. Finally, the cracking temperature of concrete decreased when the FA replacement level increased up to 50%, and converted to plateau with higher FA replacement level. Overall, FA replacement level with 50% was recommended for concrete under restraint cracking risk.

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.

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

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

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

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