Admixtures Fly Ash Research Articles

Chloride Diffusion and Induced Reinforcement Corrosion in Concrete with Fly Ash and Ground‐Granulated Blast‐Furnace Slag Exposed to Marine Submerged Zone

This paper investigates the influence of mineral admixtures fly ash (FA) and ground‐granulated blast‐furnace slag (GGBS), the byproducts of industry, on chloride ions migration and corrosion resistance performance. A novel preparation method of wire beam electrode (WEB) was also introduced to explore the excellent corrosion‐resistant capacity of concrete with mineral admixtures. By comparing concrete specimens with and without FA and GGBS, the test result of wire beam electrode, rapid chloride migration (RCM), and electrochemical tests highlight the positive impact of fly ash and GGBS against chloride ions migration, respectively. Concrete with fly ash and GGBS supplies an advanced protection effect of ordinary Portland cement; meanwhile, CO2 emission amount can be significantly reduced. Moreover, homemade wire beam electrode was proved to be a novel and reliable test method against corrosion, which has agreement with the test result of an electrochemical device.

Mechanical and Durability Properties of Concrete Incorporating Flyash

India is a second largest producer of cement in the world. about 300 million tones of cement had produced in 2012. Day to day life we using large amount of cement it causes to reduction of natural resources. By using coal 60% of electricity was produced per annum. fly ash are produced as by product in coal about 175 million tones. so as we trying to replace cement by using admixture fly ash. As per indian government norms that at least 10% of fly ash should be used during cement production.fly ash has zero percentage of binding property so we replacing the cement by fly ash up to 70% only and our motive are how the mechanical and durability properties perform in the concrete due to the replacing large amount of fly ash. we find that fly ash reduced chloride attacking in concrete, reducing the pores size, improved workability. Hence, higher volumes of fly ash can be used to replacecement in concrete mixes and care should be taken during the design mix to obtain the similar compressive strengths as that of the control mix. this can be achieved by reducing the water cement ratios of concrete mixes incorporated with higher volumes of fly ash.

Effect of Silica Fume and Fly Ash Admixtures on the Corrosion Behavior of AISI 304 Embedded in Concrete Exposed in 3.5% NaCl Solution.

The use of supplementary cementitious materials such as fly ash, slag, and silica fume improve reinforced concrete corrosion performance, while decreasing cost and reducing environmental impact compared to ordinary Portland cement. In this study, the corrosion behavior of AISI 1018 carbon steel (CS) and AISI 304 stainless steel (SS) reinforcements was studied for 365 days. Three different concrete mixtures were tested: 100% CPC (composite Portland cement), 80% CPC and 20% silica fume (SF), and 80% CPC and 20% fly ash (FA). The concrete mixtures were designed according to the ACI 211.1 standard. The reinforced concrete specimens were immersed in a 3.5 wt.% NaCl test solution to simulate a marine environment. Corrosion monitoring was evaluated using the corrosion potential (Ecorr) according to ASTM C876 and the linear polarization resistance (LPR) according to ASTM G59. The results show that AISI 304 SS reinforcements yielded the best corrosion behavior, with Ecorr values mainly pertaining to the region of 10% probability of corrosion, and corrosion current density (icorr) values indicating passivity after 105 days of experimentation and low probability of corrosion for the remainder of the test period.

Biosorption of Cd2+ using an admixture of Ulva lactuca and fly ash from coal-fired power plant

This study investigated the adsorption of Cd2+ in a simulated wastewater using green macro alga, U. lactuca and fly ash from coal-fired power plant, individually and as an admixture (25:75, 50:50, and 75:25). The maximum adsorption capacities for 0:100, 25:75, 50:50, 75:25 and 100:0 ratios of U. lactuca and fly ash were 6.47, 6.28, 6.27, 6.19, and 6.39 mg/g adsorbent, respectively. The optimum adsorption was found to occur at an initial Cd2+ concentration of 70 mg/L at 293 K, pH 5, 120-minute contact time, 300 rpm agitation speed, and 10 g/L biosorbent dosage. The obtained results fitted well with Langmuir Isotherm, suggesting a monolayer adsorption with adsorption capacity of 6.852 mg/g adsorbent. The highest adsorption capacity was observed using fly ash while the lowest was observed using 75:25 U. lactuca to fly ash ratio.

Influence of fluidized bed combustion fly ash admixture on hydrothermal synthesis of tobermorite in the mixture with quartz sand, high temperature fly ash and lime

Autoclaved aerated concrete (AAC) microstructure consists of tobermorite, which is formed in the strongly alkaline and hydrothermal environment of the CaO – SiO2 – Al2O3 – H2O system and isthe main contributor to the strength of AAC. This paper addresses the influence of fluidized bed combustion fly ash (FBC ash) on the formation of tobermorite, and the properties and structure ofautoclaved composite. To give the best account of the influence of individual input materials, tests are conducted on samples without aluminum powder, therefore the samples did not have aporous structure. Quartz sand, high temperature fly ash and lime were used as input materials, FBC ash was used as an admixture (10, 30 and 50%). The main components were mixed to achieve a molar ratio of 0.73 for CaO/SiO2. The hydrothermal reaction was carried out in saturated water vapor at 190 °C for 16 h. The main mineralogical phases and microstructure were examined using X-ray diffraction analysis and Scanning Electron Microscope. It was found that fluidized bed combustion fly ash has significant influence on the formation and crystallization of tobermorite and increases compressive strength of the samples of up to 2.5 times after 30 and 50% additions of FBC ash.

Durability Based Study of Self-compacting Concrete Having Surplus and Waste Brick Kiln Dust as Partial Replacement of Fine Aggregate

In this research work experimental work has been done to investigate the effect of using brick kiln dust in self-compacting concrete as a partial replacement of fine aggregate and its durability was also checked. The materials used were obtained from locally available. The brick kiln dust was obtained from brick kiln located near to Peshawar city where as fly ash and water reducing admixture were obtained from Sika chemicals Islamabad. Using Japanese mix design principle for SCC 5 types of mix composition were set for testing as M0 (Control mix), M10, M20, M30 & M40 having 10, 20, 30 & 40 percent brick dust in place of fine aggregate. The result obtained from all the mixes were correlated to control mix M0. Tests carried out for checking flow ability and passing ability show that as the percentage of brick dust is increasing in SCC the flowabality and passing ability of mix get reduced gradually while resistance to segregation is increased. In water absorption test, the mixture M10, and M20 were found to show good results whereas M30 and M40 show high capability of water absorption. For weight loss, compressive strength and flexure strength loss due to sulphate attack and acid attack it was found that M10 gives approximately similar results to M0. In research work it was noted that, the mix having 10 percent brick dust gives results that could be compared to control mix M0.

MICROSCOPICAL AND MICROMECHANICAL FEATURES OF HIGH PERFORMANCE CONCRETE CONTAINING LOW LEVELS OF FLY ASH

Alkali activated fly ash is a widely used admixture to the concrete. Due to the pozzolanic activity, the fly ash can replace up to 60 mass percentage. The impact of fly ash on the concrete depend on the level of it content, i.e. in small levels it improves the macro-mechanical properties and durability as well as chemical resistance. On the other side, fly ash admixture negatively influence the set time and cause slow development of strength. Therefore, the effect of small fly ash admixture levels on the micro-structure of high performance concrete (HPC) is discussed in this study.

Analysis of the Impact of Fly Ashes on the Structure of SCC Concrete Aeration

The paper presents the results of tests of the impact of fly ash admixture on the structure of aeration and on selected physical and mechanical properties of self-compacting concrete (SCC) concrete mix. The effects were compared to those obtained for SCC concrete made solely with the use of Portland cement. Tests were performed on a fresh concrete mix (spread, viscosity and air content by pressure method). The aeration parameters of the fresh concrete mix were determined by Air Void Analyser (AVA) method (total air content A, micropores content A300 and spacing factor ). For hardened concretes, the following characteristics were determined: compressive strength (after 2, 7, 28 and 56 days), water absorption, water tightness and frost resistance. Unit prices were also calculated (for prices in Poland) for SCC concrete made solely with the use of Portland cement and separately with the use of fly ash admixture. The analysis of the results demonstrated that the addition of a large amount of fly ashes to SCC concrete clearly has a negative impact on the stability and quality of its aeration characteristics and, as a consequence, significantly reduces its frost resistance and thus durability. The unit price calculated for SCC concretes made with the use of fly ash is clearly lower than of concretes made solely with the use of Portland cement, but in many cases this does not justify the use of fly ash.

Effect of Fly Ash on the Mechanical Properties of Cemented Backfill Made with Brine

Sanshandao Xinli Gold Mine in Shandong Province is the first Chinese subsea gold mine. The mine uses cement backfill in the open stopes. The existence of a high concentration of Cl− in the water use to create the cement backfill affects its strength. An analysis by scanning electron microscopy and x-ray diffraction investigated the effect of salt brine on mechanical properties of cement backfill and micro-corrosion mechanism, the suitable mineral admixture of fly ash was selected after conducting theoretical analysis to decrease the effects of brine. A relationship between the elastic modulus and the uniaxial compressive strength of the cemented backfill was determined. The density, cohesion and internal friction angle of the cemented backfill were obtained. Based on x-ray diffraction analysis of fly ash, scanning electron microscope test and testing the addition of fly ash in varying amounts and ways of introduction, the mechanism for improving the uniaxial compressive strength of the cement backfill produced with the fly ash and the best mixing quantity of the fly ash was determined in briny conditions through experiments and theoretical research. Rheological properties of the filling slurry with fly ash were also investigated.

Biomass fly ash and aluminium industry slags-based geopolymers

Geopolymers are a new class of non-Portland cements produced using an alumino-silicate material and an activating solution, which is mainly composed of sodium or potassium and waterglass to be subsequently cured at relatively low temperatures. Those can be formulated by adding natural minerals, waste and/or industrial by-products. The study investigates the microstructural properties of geopolymers synthesized from metakaolin (MK) and the admixture of fly ash (FBA) and aluminium industry slags (AIS) at different ages of curing. Five different geopolymer compositions were prepared and characterized by XRD, ATR-FTIR and SEM/EDS. The study revealed that geopolymeric gels are identified, which show mainly glassy microstructures, in agreement with the X-ray amorphous diffraction patterns, broad FTIR features and confirmed by SEM/EDS, with promising results prior to an industrial scale.

Study of compressive strength evolution in soil cement samples with fly-ash admixtures

Improving a soil is a process of increasing its physical/mechanical properties without changing its natural structure. Improvement is reached by means of the knitted materials, or other methods when strong connection between soil particles is established. The main reason of designing cement-soil columns is to improve properties of local soils (such as strength and stiffness) by mixing them with various cementing materials. Cement and calcium are the most commonly used binders. However, new research undertaken worldwide proves that apart from these materials, also gypsum or fly ashes can also be successfully implemented. As the Deep Soil Mixing is still being under development, anticipating mechanical properties of columns in particular soils and the usage of cementing materials in formed columns is very difficult and often inappropriate to predict. That is why a research is carried out in order to find out what binders and mixing technology should be used. The paper presents several results of the testing procedures related to soil-cement quality and internal capacity of Deep Soil Mixing columns. Presented results concerning capacity testing of laboratory samples and laboratory procedures on various categories of samples were picked from R&D and consulting works offered by Wroclaw University of Science and Technology (WrUST). The work contains two independent groups of analyses. The first one comprises results coming from the previous laboratory research undertaken at the University. This is just a small part of huge investigation which is aimed at boosting the knowledge of possible implementation of fly ashes into the DSM columns. The second part contains results of specimen prepared by the author for the purpose of MSc Diploma Work.

An investigation of green diesel produced through hydro-processing of waste cooking oil using an admixture of two heterogeneous catalysts

ABSTRACTEnergy crisis, global warming, and rapid depletion of fossil fuel reservoirs are knocking the door for alternative fuel. This study explores the hydro-processing of waste cooking oil using mixtures of two heterogeneous catalysts (admixture of calcium oxide and biomass-based thermal power plant fly ash (​BBTPFS)) in different proportions (10, 20, 30, and 40% of CaO in BBTPFS by wt%) to analyze the effect on the yield of bio-crude, organic liquid fraction (OLF), and acidity index. The high-pressure high-temperature reactor was used for hydro-processing, and True Boiling Point (TBP) distillation unit was used for fractional distillation of the bio-crude obtained within the boiling range, 35–140°C, 140–180°C, 180–370°C, and 370–482°C as per ASTM D2892 and ASTM D5236 specification. The yield of bio-crude and OLFs and their characterization have been analyzed and compared with literature work. It was observed that 20 wt% of CaO in BBTPFS catalyst was the optimized admixture to obtain the maximum yield of bio-crude (93.85 vol%) and OLFs (66.29 vol%) with lower acidity index.

Comparison of creep of the cement pastes included fly ash

The paper is devoted to comparison of creep of cement pastes containing fly ash admixture. The size of creep in time depends on the amount of components of the cement paste. Attention is paid to the content of classical fly ash in cement paste and its impact on the size of creep. The moisture of cement pastes is distinguished because it significantly affects the rheological properties of the material.

Comparison of Cement Pastes Creep with Admixtures of Fly Ash

The article is devoted to compare the size of the creep for a time period of cement pastes with admixture of different amounts of fly ash. Attention is given to the size of the deformations that occur in materials saturated with water and also in the dried matrices. The presented results comparing creep size for cement pastes containing fly ash 30 and 50 %. Influence of the amount of ash and the amount of water to the creep size is evaluated in the conclusion.

Performance Study of Self-Compacting Concrete by Fly Ash and Silica Fume for Sustainability in Building Construction

Self – compacting concrete (SCC) is a high – performance concrete that can flow under its own weight to completely fill the form work and self-consolidation without any mechanical vibration. Green concrete is defined as a concrete which uses waste material as at least one of its components, or its production process does not lead to environmental destruction. Such concrete can accelerate the placement, reduce the labor requirements needed for consolidation, finishing and eliminate environmental pollution. One alternative to reduce the cost of self-compacting concrete is the use of mineral admixtures such as silica fume, ground granulated blast furnace slag and fly ash, which is finely, divided materials added to concrete during mixture procedure .When mineral admixtures replace a part of the Portland cement, the cost of self-compacting concrete will be reduced especially if the mineral admixtures are waste or industrial by-product. The various tests for compressive, tensile and flexural strength are determined for various specimens with certain percentages ( 10 % ,30 % ) of replacement like silica fume, fly ash and combination of both fly ash and silica fume. Admixture combination of fly ash and silica fume replacing 30 % results in maximum compressive strength. Admixture of fly ash replacing 10 % results in maximum tensile and flexural strength. In order to make SCC effective, trials can be made with partial replacement of combining silica fume and fly ash to achieve the higher compressive strength. Minimum replacement of fly ash can be investigated to achieve higher tensile and flexural strength .With respect to the above combination of replacement SCC can be dealt with its several specializations to make it effective.

Influence of fly-ashes on properties of ordinary concretes

Abstract Influence of fly-ashes on properties of ordinary concretes. Care of the environment in accordance with the principles of sustainable development introduces the possibility and need for waste recycling. The construction and building materials industry has the greatest potential for reuse of waste. The article presents the results of investigations of selected properties (consistency, water absorbability, compressive strength and tensile strength after 28 and 56 days of curing, depth of penetration) of ordinary concretes and concretes containing fly-ashes - calcareous and siliceous ash − in their composition. To make the samples, the Portland cement CEM I 42.5 R and natural aggregate with graining of 0-16 mm were used. The concrete with siliceous and calcareous admixtures was made in three lots where the ash was added in the quantity of 15, 20 and 30% of the cement mass. After the tests, it was stated that the fly-ash admixture does not increase the air content in the mix, it increases the compressive strength in time and the siliceous ash improves the splitting tensile strength.

Optimum fly ash proportion in concrete to sustain the impact imposed by diesel

The paper reports an experimental investigation on the deterioration of diesel on concrete specimens. Also, it is found that this deteriorating effect is lessened with partial replacement of fly ash. Concrete specimens with a water-concrete ratio of 0.47 with ten different percentages of fly ash replacements are used for the study. The specimens are subjected to both water curing and diesel soaking. The specimens are analysed with standard suites like the scanning electron microscope (SEM), X-ray diffraction (XRD) and sorptivity tests with the ground truth rendered by compressive strength (CS) analysis. We perform detrended fluctuation analysis (DFA) to get an insight on the significance of the XRD data buffered with varying window sizes of the XRD data series. It is evident from the results that 30% replacement of fly ash admixture is optimum for surpassing the negative impact of diesel on concrete.

SUSTAINABLE STRUCTURAL LIGHTWEIGHT CONCRETE DESIGN AND THE INVESTIGATION OF THE MECHANICAL PROPERTIES

This paper reports an experimental investigation and statistical analysis carried out to evaluate sustainable structural lightweight concrete (SSLWC) design and the mechanical properties of SSLWC. CEM I 42,5 N cement was partially replaced with silica fume (SF) 10% and fly ash (FA) 30% by weight, respectively. The tests of compressive, split tensile strength and ultrasonic pulse velocity were performed on the specimens prepared with admixtures at ages of 3, 28 and 90 days. From the results it was seen that specimens prepared with SF showed better strength properties than others. While control concrete specimens showed similar strength properties to concrete specimens with SF admixture at early age, those of concrete specimens with FA admixture did not increase at the same age. Furthermore, FA concrete series gave very close results to control concrete at advanced age. In this study, analysis of variance (ANOVA) and F-test were performed to see the effects of the experimental parameters on results.

Powder Resistivity Inferred Differential Collection of Heterogeneous Coal Fly Ash and Powered Activated Carbon Admixtures Within a Cylindrical Electrostatic Precipitator

One of the primary goals of U.S. EPA’s Mercury Air Toxics Standards (MATS) is to remove approximately 90 % of mercury emissions from coal-fired power plants (CFPPs). Sorbent injection upstream of electrostatic precipitators (ESPs) has been the leading method for capturing mercury at CFPPs. However, electrostatic precipitators (ESPs) that are marginally sized and/or operated may face new performance challenges due to sorbent injection. Injected mercury sorbent particles having different properties (i.e., particle size, surface chemistry, or electrical properties), mixing with native fly ash, can potentially affect the collection behaviors of ESPs. The present study uses powder resistivity to study the differential collection behaviors within a cylindrical ESP by manually feeding admixtures containing Norit DarcoⓇ FGD powdered activated carbon (PAC) and fly ash samples from either Powder River Basin (PRB) or Illinois bituminous coals. Powder resistivity measurements, performed on fly ash admixtures at various PAC ratios (i.e. 0−10 wt. %) prior to ESP processing, serve as the initial resistivity data to infer the impact of PAC injection on ESP collection by comparing to powder resistivity of samples collected from the collection electrode. This study presents not only the evidence of differential collection behaviors within an ESP but also the implications for mercury emissions and the particulate matter (PM) control through ESPs.

Modeling the thermal response of hydrating cemented gangue backfill with admixture of fly ash

Cemented gangue backfill (CGB), which is a composite material mixed by coal gangue, binder and water, is used for coal mine backfill to control strata movement and thus, reduce ground surface subsidence. Whether a CGB structure can successfully play the role of supporting the overlying roof or not is dependent on its mechanical strength, which is significantly affected by the temperature development in it. The temperature of CGB is influenced by the heat generated by binder hydration and the heat transfer between the CGB and its surroundings. In this paper, a numerical model is proposed to predict the temperature development and distribution within the hydrating CGB structure. Results from an experimental study are employed to validate the developed model. This validation outcome indicates that the model simulation is in a good agreement with the experiment investigation. The validated model is then used to analyze the effects of various factors on the temperature development within the CGB structure versus curing time.