Fly Ash Materials Research Articles

Application of Advanced Machine Learning Approaches to Predict the Compressive Strength of Concrete Containing Supplementary Cementitious Materials.

The casting and testing specimens for determining the mechanical properties of concrete is a time-consuming activity. This study employed supervised machine learning techniques, bagging, AdaBoost, gene expression programming, and decision tree to estimate the compressive strength of concrete containing supplementary cementitious materials (fly ash and blast furnace slag). The performance of the models was compared and assessed using the coefficient of determination (R2), mean absolute error, mean square error, and root mean square error. The performance of the model was further validated using the k-fold cross-validation approach. Compared to the other employed approaches, the bagging model was more effective in predicting results, with an R2 value of 0.92. A sensitivity analysis was also prepared to determine the level of contribution of each parameter utilized to run the models. The use of machine learning (ML) techniques to predict the mechanical properties of concrete will be beneficial to the field of civil engineering because it will save time, effort, and resources. The proposed techniques are efficient to forecast the strength properties of concrete containing supplementary cementitious materials (SCM) and pave the way towards the intelligent design of concrete elements and structures.

Estimation of Iodine Leaching in Soil Amended with Organic and Inorganic Materials Using HYDRUS 1-D Model

This study investigated the ability of a HYDRUS 1D model for predicting the vertical distribution of potassium iodine (200 ppm) in soil columns after amendment with five different common remediation materials (gypsum, lime, fly ash, charcoal, and sawdust) at a rate of 2.5% (w/w), relative to an unamended control soil. Results showed that relative to the unamended soil, iodine leaching was decreased by all amendments but that the magnitude of the decreases varied with the soil amendment applied. Iodine content was highest in the upper layer of the soil columns and decreased progressively with soil depth. The model was evaluated via comparison of the model simulated values with measured values from the soil column studies. The results showed that the HYDRUS 1D model efficiency was near to 1, indicating the stimulated results near to the measured values. Therefore, this study showed that iodine leaching through a soil could be ascertained well using a HYDRUS 1D model. The model over predicted iodine leaching, results in a weak correspondence between the simulated and the measured results for iodine leaching. This suggests that the HYDRUS-1D model does not explain accurately different organic and inorganic amended soil and the preferential flow that occurs in these columns. This may be due to the fact that Freundlich isotherm, which is part of the transport equations, does not sufficiently describe the mechanism of iodine adsorption onto the soil particles. This study would help to select an amendment for an effective management strategy to reduce exogenous iodine losses from agro-ecosystems. This would also improve scientific understanding of iodine transport in soil profile.

The influence of containing supplementary cementitious materials on preparation and properties for UHPC

The preparation of ultra-high performance concrete usually required expensive materials and harsh curing conditions, which limited its application in engineering widely. It may be solved by adding supplementary cementitious materials (fly ash, ground granulated blast slag, silica fume and so on). This paper is dedicated to determining the optimal mix ratio of UHPC under common preparation methods and raw materials and under common maintenance conditions to expand the applications of UHPC. The influence of the ratio of water to binder, the ratio of sand to binder, the content of supplementary cementitious materials on UHPC slump spread, compressive strength of 7 days and 28 days, apparent density and tensile strength of 28 days were researched by orthogonal test. The results revealed that the method of semi-dry mixing could enhance the homogeneity of steel fiber and improve the rate of its utilization. When the replacement of cement achieved 50% by the supplementary cementitious materials, the performances of UHPC were still guaranteed and confirmed. When the ratio of sand to binder reached 1.1, the ratio of water to binder reached 0.17, ground granulated blast slag was 25%, fly ash was 10% and silica fume was 15%, its slump spread reached 580 mm, compressive strength and tensile strength reached 152.9 MPa and 14.2 MPa respectively in 28 days under natural curing conditions. Therefore, the UHPC with supplementary cementitious materials should be considered as one of the sustainable development and environmental protection materials.

Utilization of coal fly ash waste for effective recapture of phosphorus from waters

Reutilization of the waste by-products from industrial and agricultural activities is crucially important towards attainment of environmental sustainability and the ‘circular economy’. In this study, we have developed and evaluated a sustainably-sourced adsorbent from coal fly ash, which was modified by a small amount of lanthanum (La-FA), for the recapture of phosphorous (P) from both synthetic and real natural waters. The prepared La-FA adsorbent possessed typical characteristic diffraction peaks similar to zeolite type Na–P1, and the BET surface area of La-FA was measured to be 10.9 times higher than that of the original FA. Investigation of P adsorption capability indicated that the maximum adsorption (10.8 mg P g−1) was 6.14 times higher than that (1.8 mg P g−1) of the original fly ash material. The ζ potentials measurement and P K-edge X-ray Absorption Near Edge Structure (XANES) spectra demonstrated that P was bonded on La-FA surfaces via an adsorption mechanism. After applying the proposed adsorbent to real lake water with La/P molar ratios in the range from 0.5:1 to 3:1, the La-FA adsorbent showed the highest phosphate removal ability with a La/P molar ratio 1:1, and the P adsorption was similar to that performance with the synthetic solution. Moreover, the La-FA absorbent produced a negligible effect on the concentrations of total dissolved nitrogen (TDN), NH4+-N and NO3−-N in water. This study thus provides a potential material for effective P recapture and details of its operation.

Determination of the Influence of Hydraulic Additives on the Foaming Process and Stability of the Produced Geopolymer Foams.

The research described in this article was aimed at determining the influence of hydraulic additives on the foaming process and the stability of the produced geopolymer foams. These foams can be used as insulation materials to replace the currently commonly used insulations such as expanded polystyrene or polyurethane foams. Geopolymers have low thermal conductivity, excellent fire- and heat-resistant properties, and have fairly good mechanical properties. Research on foamed materials shows that they have the highest class of fire resistance; therefore, they are most often used as insulation products in construction. Geopolymer foams were made of aluminosilicate materials (fly ash) and foaming agents (H2O2 and Al powder), and the stabilizers were gypsum and portland cement. Additionally, surfactants were also used. It was found that better foaming effects were obtained for H2O2—it is a better foaming agent for geopolymers than Al powder. When using a hydraulic additive—a stabilizer in the form of cement—lower densities and better insulation parameters were obtained than when using gypsum. Portland cement is a better stabilizer than gypsum (calcium sulfates), although the effect may change due to the addition of surfactants, for example.

Monitoring of Chemical Resistance of New Grouting Materials

This paper deals with the study of chemical resistance of new cement-based grout for invert grouting. The aim of this work is to verify new mixtures with specific admixtures. The study monitors resistance to external sulphate attack. Specimens were placed into sulphate solution 29.8 g∙l-1 (44 g∙l-1 Na2SO4) according to DIN19753 standard. Based on the results gained, new mixtures will be designed and optimized by addition of suitable secondary raw materials (fly ash, waste foundry sand, waste glass, waste filers).

Salt frost resistance and micro characteristics of polynary blended concrete using in frost areas

To explore the deterioration process and improvement mechanism concrete blended with supplementary cementitious materials (fly ash, slag, and silica fume) in frozen areas, the SCM content, w/b ratio, curing age, freeze-thaw (F-T) cycle, and salt-frost (S-F) cycle were varied to systematically evaluate the chloride permeability resistance and S-F resistance. Pore structures, hydration degree, phase composition and interfacial transition zone (ITZ) between aggregate and matrix of investigated mixtures were characterized by mercury intrusion porosimetry (MIP), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and SEM-EDS, respectively. The S-F resistance of blended concrete is greater than that of control mixture without SCMs. The crystallization pressure is dominated by larger saturation with higher salt concentration at the early stage of S-F cycles, and greatly affected by the actual volume expansion of salt solutions at its later stage. SCMs can compensates the structure deterioration under S-F and F-T conditions, where quaternary blends shows an optimal refinement for the pore structures. It is found that the total pore volume, average pore size, and porosity are highly correlated with the chloride permeability resistance of concrete by grey degree analysis. The SCMs blends can improve cement hydration degree by pozzolanic and hydraulic reactions at the later curing age. With the S-F cycles, the internal stresses could cause pore nucleation and crack propagation, while SCMs can effectively control the ITZ width and mitigate the structural deterioration of concrete.

A Comprehensive Study on the Hardening Features and Performance of Self-Compacting Concrete with High-Volume Fly Ash and Slag.

The main concern of this work is to evaluate the influences of supplementary cementitious materials (fly ash, slag) and a new type of polycarboxylate superplasticizer containing viscosity modifying agents (PCE-VMA) on the performance of self-compacting concrete (SCC). The workability, hydration process, mechanical property, chloride permeability, degree of hydration and pore structure of SCC were investigated. Results indicate that the addition of fly ash and slag slows down early hydration and decreases the hydration degree of SCC, and thus leads to a decline in compressive strengths, especially within the first 7 days. The addition of slag refines pore structure and contributes to lower porosity, and thus the chloride permeability of SCC is decreased during the late hydration stage. Additionally, a new factor of calculated water–binder ratio is put forward, which can directly reflect the free water content of concrete mixture after mixing, and guide the mix proportion design of SCC.

Synthesis of Fly Ash-Based Zeolite and its Research Progress in Wastewater Treatment

Fly ash is the most common solid waste in the industry, and its high value-added utilization has become a hot issue of study. Carrying out the green synthesis route of zeolite as the raw material of fly ash has become an extremely important scientific significance and practical value. In this paper, the research progress of fly ash-based zeolite was introduced from three aspects, including fly ash activation method, fly ash-based zeolite synthesis method and fly ash-based zeolite in the wastewater treatment sector. The relevant applications of fly ash-based zeolite as an adsorbent material in the treatment of wastewater pollution were summarized, and the development trend has prospected.

Compaction characteristics of natural cohesive subgrade soil stabilized with local sustainable materials

In traditional road construction, the most common source materials for roadbed layers are the borrow pits. During the construction process, the source’s materials, excavation, loading, and handling have been considered significant factors on total construction cost. Improving the geotechnical properties of the locally available source materials using the waste materials of the local industry (as additives) is helped in avoiding undesirable additional costs in the field construction. The present paper explains the results of an experimental study of compaction characteristics for subgrade material of districts of Baghdad, Iraq with two different types of local byproduct materials “cement dust and fly ash materials,”. The selected soil, cement dust, and fly ash mixtures were made ready for use in the laboratory, and the mixtures’ compaction properties were investigated. Both light and heavy manual compaction tests were carried out and compared. The effect of selected stabilizers on the compaction behavior of the subgrade soil was determined to obtain the optimal values of stabilizer materials. The finding of this paper indicates that the compaction characteristics and behavior of the subgrade soil greatly depend on the type of additives used. However, the subgrade stabilization with local byproduct materials is beneficial from economic and environmental points of view.

Experimental studies on durability properties of Sustainable and Eco-friendly materials of GGBS and Fly ash in reinforced cement concrete

This paper represents the use of supplementary cementitious material (SCM) with the blend of Portland cement in producing the corrosion resistive concrete. Fly ash and GGBS are partially replaced in three different ratios by the weight of cement. Compressive strength, chloride penetration, corrosion, sorptivity of (FA-GGBS) were determined. The test revealed the confrontation by chloride ions through the infiltration of concrete improves substantially by replacement coal by-product Fly ash, GGBS, and improvement increase with increases in the replacement level. The corrosion resistance of SCM-Proportional Mixes was better than the Control mix concrete. Besides, test results indicated that reduction of permeability of chlorides ion as a reduction in porosity in the concrete, that associates with increases in the compressive strength. It significantly affects the durability of the Supplementary Cementitious Materials. On the same proportional mixes, we have gone with microstructural analysis of Scanning Electron Microscopy (SEM) and (EDX), X-Ray Diffraction and non-Destructive tests are following method. The work is suggested that the higher replacement of cement with SCM shows more satisfactory results in the durability properties of proportional grades of SCM.

Experimental Study on Mechanics and Water Stability of High Liquid Limit Soil Stabilized by Compound Stabilizer: A Sustainable Construction Perspective

Sustainable highway construction and operation are threatened by high-liquid-limit soil with low strength and poor water stability in Dongting Lake areas. In order to obtain a soil stabilizer that can effectively improve its strength and water stability, first the author selected inorganic materials (cement, quicklime and fly ash) and sulfonated oil (SO) as the main components of the composite soil stabilizer. Then, a series of single admixture tests were carried out to explore the strength and water stability mechanism of single admixture stabilized soil. Finally, a series of orthogonal experiments and cost analyses were carried out to obtain the formula of the composite stabilizer. According to the results of single doping, inorganic materials can significantly enhance the strength and stiffness of high-liquid-limit soil. The content of SO has a strong correlation with the water stability of high-liquid-limit soil. On a microscopic scale, X-ray diffraction patterns and scanning electron microscopy images explained this law. According to the orthogonal results, the formula of the composite soil stabilizer is: cement 4.5%, quicklime 1.5%, fly ash 2.5%, and SO 0.2%. This paper provides a method to improve high-liquid-limit soil, which is beneficial to sustainable construction and operation of the highway.

Influence of the Fly Ash Material Inoculants on the Tensile and Impact Characteristics of the Aluminum AA 5083/7.5SiC Composites.

The choice of suitable inoculants in the grain refinement process and subsequent enhancement of the characteristics of the composites developed is an important materials research topic, having wide scope. In this regard, the present work is aimed at finding the appropriate composition and size of fly ash as inoculants for grain refinement of the aluminum AA 5083 composites. Fly ash particles, which are by products of the combustion process in thermal power plants, contributing to the large-scale pollution and landfills can be effectively utilized as inoculants and interatomic lubricants in the composite matrix–reinforcement subspaces synthesized in the inert atmosphere using ultrasonic assisted stir casting setup. Thus, the work involves the study of the influence of percentage and size of the fly ash dispersions on the tensile and impact strength characteristics of the aluminum AA 5083/7.5SiC composites. The C type of fly ash with the particle size in the series of 40–75 µm, 76–100 µm, and 101–125 µm and weight % in the series of 0.5, 1, 1.5, 2, and 2.5 are selected for the work. The influence of fly ash as distinct material inoculants for the grain refinement has worked out well with the increase in the ultimate tensile strength, yield strength, and impact strength of the composites, with the fly ash as material inoculants up to 2 wt. % beyond which the tensile and impact characteristics decrease due to the micro coring and segregation. This is evident from the microstructural observations for the composite specimens. Moreover, the role of fly ash as material inoculants is distinctly identified with the X-Ray Diffraction (XRD) for the phase and grain growth epitaxy and the Energy Dispersive Spectroscopy (EDS) for analyzing the characteristic X-Rays of the fly ash particles as inoculant agents in the energy spectrum.

Pengaruh Penambahan Fly Ash Terhadap Perilaku Teknis Tanah Ekspansif di Daerah Selimau Kabupaten Bulungan

Expansive soil is one of the problematic soils for civil engineering construction. The high swelling-shrinkage nature results in deformations that can damage the construction on it, therefore it is necessary to make improvements in expansive soil. One of the most widely used methods of improving expansive soil is stabilization using chemical additives. In this research using coal waste material (fly ash) as stabilizer from PLTU Sekayan in Kaltara Province, so it can be said as environmentally friendly stabilization. The research objective was to determine changes in engineering behavior of expansive soil through compaction tests and CBR. The test results will be displayed in graphical form, namely by comparing the expansive soil that has not been stabilized (initial conditions) and the expansive soil that has been stabilized with fly ash at mixed variations of 20%, 30% and 40%, and has passed the curing period for 5, 15, and 30 days. From this research, it was found that the addition of a stabilizer (fly ash) could improve its engineering properties, and the optimum results were obtained at the addition of 40% fly ash and after 30 days of curing time. From the compaction test, it was found that the volume weight of dry soil (γdry) increased by 14.05% from 1.21 gr/cm3 to 1.38 gr/cm3 and the optimum water content (wopt) decreased by 38.12% from 31.19% to 19,3%. From CBR testing in the laboratory, there was a very large increase in the value of CBRDesign, namely 2192% from 0.72% to 16.5%

АНАЛИТИЧЕСКИЕ ПОДХОДЫ К КОЛИЧЕСТВЕННОМУ ОПРЕДЕЛЕНИЮ СОДЕРЖАНИЙ ХИМИЧЕСКИХ ЭЛЕМЕНТОВ В УГЛЯХ И УГЛИСТЫХ ПОРОДАХ С ИСПОЛЬЗОВАНИЕМ МЕТОДОВ ИСП-МС И ИНАА

Актуальность исследования обусловлена значительным интересом ученых, работающих в области угольной геологии, и специалистов химико-аналитических лабораторий, практикующих элементный количественный анализ объектов окружающей среды, к проблематике высокоточного определения низких содержаний химических элементов в углях и угольных материалах для последующего применения полученных данных при решении научных и различных технологических задач. Цель: рассмотреть и обобщить наиболее часто используемые методические подходы к определению химических элементов в широком диапазоне их содержаний в углях (угольных материалах), а также оценить правильность и точность результатов метода ИСП-МС после открытого кислотного разложения проб и их сплавления с метаборатом лития, сопоставлением получаемых данных с результатами метода ИНАА и статистической обработкой данных. Объекты: угли, углистые алевролиты и углефицированная древесина месторождения германия Спецугли, расположенного на юго-западной окраине Ханкайского массива в восточной части Павловской угленосной впадины, Приморский край. Методы: масс-спектрометрия с индуктивно-связанной плазмой (ИСП-МС), применённая после перевода исследуемых образцов в растворенную форму, и неразрушающий метод количественного инструментального нейтронно-активационного анализа (ИНАА). Для обработки полученных результатов были использованы методы математической статистики. Результаты. Получены результаты ИСП-МС анализа трех стандартных образцов утвержденного типа (СО) состава золы уноса угля КАТЭКа ГСО 9237-2008 (ЗУК-2), золы бурого угля Азейского месторождения ГСО 7177-95 (ЗУА-1) и битуминозного угля CLB-1 Геологической службы США, представленные в виде данных об их микроэлементном составе в сравнении с аттестованными и рекомендованными значениями. Результаты определения части элементов, приведенные нами, дополняют представленные в паспорте данные по этим СО. Проведено сопоставление ИСП-МС результатов анализа для проб углей и углистых пород после различных способов химической пробоподготовки: методики открытого кислотного разложения и сплавления с метаборатом лития. Изучено поведение отдельных элементов во время этих процессов. Выполнено сравнение полученных данных по ИСП-МС и ИНАА методам. Все результаты обработаны метрологически, и показано их допустимое расхождение.

Influence of Fine Recycled Concrete Powder on the Compressive Strength of Self-Compacting Concrete (SCC) Using Artificial Neural Network

This paper aims to investigate the effect of fine recycled concrete powder (FRCP) on the strength of self-compacting concrete (SCC). For this purpose, a numerical artificial neural network (ANN) model was developed for strength prediction of SCC incorporating FRCP. At first, 240 experimental data sets were selected from the literature to develop the model. Approximately 60% of the database was used for training, 20% for testing, and the remaining 20% for the validation step. Model inputs included binder content, water/binder ratio, recycled concrete aggregates’ (RCA) content, percentage of supplementary cementitious materials (fly ash), amount of FRCP, and curing time. The model provided reliable results with mean square error (MSE) and regression values of 0.01 and 0.97, respectively. Additionally, to further validate the model, four experimental recycled self-compacting concrete (RSCC) samples were tested experimentally, and their properties were used as unseen data to the model. The results showed that the developed model can predict the compressive strength of RSCC with high accuracy.

Comparison of the Influence of Silica‐rich Supplementary Cementitious Materials on Cement Mortar Composites: Mechanical and Microstructural Assessment

The silica-rich supplementary cementitious materials (SCMs) are the key components of mechanical and microstructural properties. The use of SCMs results in improving the mechanical and microstructural properties and decreasing the environmental burden caused by cement production. In this regard, this paper reports a study to compare the influence of silica-rich supplementary cementitious materials (slag, fly ash, and bottom ash) having similar Blaine fineness on cement mortar composites in terms of mechanical and microstructural properties. The Blaine fineness of supplementary cementitious materials was chosen at cement Blaine fineness by using short grinding time due to minimize energy consumption and cost. Supplementary cementitious materials (slag, fly ash, and bottom ash) were ground at similar cement Blaine fineness (~ 3300 cm2/g) and then by replacing 5 % and 20 % with cement, the 7-, 28-, 90-day mechanical and microstructural properties of cement mortar composites incorporating SCMs were examined. As a result, it was observed that the compressive strength properties of cement mortar composites incorporating 20 % slag gave similar strength of control samples (without SCM) according to samples with fly ash and bottom ash having similar fineness and this will decrease the required amount of cement and grinding time for the target strength properties, thus the number of CO2 emitted to nature will also decrease and less energy consumption, and the cost-effectiveness will be ensured by shorter grinding time for target strength.

Effect of fly ash and bottom ash on the ratio of splitting tensile strength to compressive strength of concrete

The construction industry has suffers from extra ordinary utilization of cement and sand in all the part of globe. For overcome the future scarcity issue partial replacement to cement with option of fly ash material and fine aggregate or sand with bottom ash prove better solution. For this study, effect of different water cement ratio mainly 0.5, 0.55, 0.6 evaluated on binder content 300kg/m3 of concrete. f/c (fly ash/cement) ratio also taken into account with wide range as 0, 0.11, 0.25, 0.43, 0.67 and 1.0. The mechanical strength of concrete specimens evaluated. The traditional practice generally neglected the issue of splitting to compressive ratio(ft/fc). In this experimental investigation, the value of ft/fc ratio found between ranges 6.76 to 11. This range are principally important for fly ash + bottom ash involvement in concrete for determining mechanical strength which has interlink to each other.

Flowability and strength properties of high volume of fly ash material on self-compacting concrete

The detail complexity level of the building structure is getting more complicated. The use of a high volume of fly ash self-compacting concrete (HVFA-SCC) with better flowability properties is one alternative to address this problem. This research aims to investigate the strength properties and flowability of a high volume of fly ash self-compacting concrete (HVFA-SCC). The primary materials of HVFA-SCC were Ordinary Portland Cement (OPC), fly ash as OPC replacement material, fine and coarse aggregates. The ratio of OPC to fly ash was 0.500:0.500, 0.475:0.525, and 0.450:0.550. The strength properties were determined based on compressive strength and porosity in hard concrete conditions at 28 days. While the flow abilities were identified conforming slump test and slump flow in fresh concrete condition directly after a mixing process. The results show that the substitution of 0.500 fly ash as shown by the HVFA-SCC-2 specimen gives the best strength properties and flow abilities. The highest strength was achieved at 32.4 MPa with a porosity of 0.48 at 28 days-age. The slump and slump flow properties also demonstrate a good flow behavior under EFNARC standard with a slump of 26.1 cm and a slump flow of 656.9 mm. It can be concluded that the 50% substitution ratio of fly ash can replace the role of OPC in HVFA-SCC and improve its strength properties and flow behavior. The use of fly ash also able to overcome the global warming issue regarding OPC production.

The effect of TiO2 addition on thermal resistance of geopolymer mortar based low alumina fly ash

The utilization of fly ash with low alumina has been carried out. The addition of TiO2 to the base material of fly ash and fly ash added with 20% metakaolin mixed with an alkaline solution has been characterized by heat resistance, compressive strength and porosity. These results indicate that the addition of TiO2 to both fly ash and fly ash with an additional 20% metakaolin shows a reduction in porosity reduction, an increase in the compressive strength value, and an increase in the thermal resistance of the sample. Despite an increase in the compressive strength value, however, the minimum requirement for a fire brick has not been achieved.