scholarly journals An SEM Investigation of the Pozzolanic Activity of a Waste Catalyst from Oil Refinery

2012 ◽  
Vol 18 (S5) ◽  
pp. 75-76
Author(s):  
C. Costa ◽  
P. Marques ◽  
P. A. Carvalho
Keyword(s):  
Zeolite Y ◽  
Active Phase ◽  
Pozzolanic Reaction ◽  
High Reactivity ◽  
Oil Refinery ◽  
Engineering Properties ◽  
Partial Replacement ◽  
Reaction Products ◽  
Fcc Catalyst ◽  
Cement Based Materials

The most active phase of the fluid catalytic cracking (FCC) catalyst, used in oil refinery, is zeolite-Y which is an aluminosilicate with a high internal and external surface area responsible for its high reactivity. Waste FCC catalyst is potentially able to be reused in cement-based materials - as an additive - undergoing a pozzolanic reaction with calcium hydroxide (Ca(OH)2) formed during cement hydration. This reaction produces additional strength-providing reaction products i.e., calcium silicate hydrate (C-S-H) and hydrous calcium aluminates (C-A-H) which exact chemical formula and structure are still unknown. Partial replacement of cement by waste FCC catalyst has two key advantages: (1) lowering of cement production with the associated pollution reduction as this industry represents one of the largest sources of man-made CO2 emissions, and (2) improving the mechanical properties and durability of cement-based materials. Despite these advantages, there is a lack of fundamental knowledge on pozzolanic reaction mechanisms as well as spatial distribution of porosity and solid phases interactions at the microstructural level and consequently their relationship with macroscopical engineering properties of catalyst/cement blends.

scholarly journals Microscopy: A tool for quantitative pozzolanic activity in blended cements

2013 ◽  
Vol 19 (S4) ◽  
pp. 97-98 ◽  
Author(s):  
C. Costa ◽  
I. Laginha ◽  
P.A. Carvalho
Keyword(s):  
Weight Ratio ◽  
Pozzolanic Activity ◽  
Oil Refinery ◽  
The Other ◽  
Partial Replacement ◽  
X Ray ◽  
Cementitious Matrix ◽  
Fcc Catalyst ◽  
Other Hand ◽  
Oil Cracking

The reuse of waste fluid catalytic cracking (FCC) catalyst, from oil-refinery industry, as a partial substitute of cement is a promising way of reducing the environmental impact of cement production and, therefore, contributes for industrial sustainability. On the other hand partial replacement of cement by oil-cracking catalysts up to 10-15% (w/w) results in improved mechanical properties as the waste catalyst tends to react with Ca(OH)2 - liberated upon cement hydration - and forms additional strength-providing reaction products. Nevertheless, the pozzolanic reaction mechanisms between cement and the waste FCC catalyst, which involve Ca migration from the cementitious matrix into the FCC particles is still not well understood.In the present study waste FCC catalyst has been incorporated in cement paste mortars with a 15:85 weight ratio. The microstructural evolution of the blended materials has been investigated by X-ray diffraction and scanning electron microscopy coupled with X-ray energy dispersive spectroscopy after curing times of 2, 7 and 28 days. Namely, the evolutions of the catalyst crystal structure and of the calcium content in the dispersed catalyst particles have been evaluated.The results show that the Ca/(Si,Al) ratio in the catalyst particles tends to increase during the cure. However, the inward migration does not occur in a continuous front but rather tends to follow high-diffusivity paths resulting in Ca depleted rims (Fig. 1). On the other hand the presence of heavy metals resulting from oil-cracking (such as La) remains essentially unaltered after a cure of 28 days. The present study demonstrates that the diffusion of Ca from the surrounding cementitious matrix into the dispersed catalyst particles plays an important role in the pozzolanic activity of the system.The authors acknowledge the funding by Fundação para a Ciência e Tecnologia through PTDC/ECM/113115/2009 and PEST-OE/CTM-UI0084/2011 grants.

Mechanism of Cement Paste with Different Particle Sizes of Bottom Ash as Partial Replacement in Portland Cement

2017 ◽  
Vol 68 (10) ◽  
pp. 2367-2372 ◽  
Author(s):  
Ng Hooi Jun ◽  
Mirabela Georgiana Minciuna ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Tan Soo Jin ◽  
Andrei Victor Sandu ◽  
...  
Keyword(s):  
Portland Cement ◽  
Construction Material ◽  
Bottom Ash ◽  
High Volume ◽  
Cement Composite ◽  
Pozzolanic Reaction ◽  
High Specific Surface Area ◽  
Partial Replacement ◽  
Natural Aggregates ◽  
Pozzolanic Properties

Manufacturing of Portland cement consists of high volume of natural aggregates which depleted rapidly in today construction field. New substitutable material such as bottom ash replace and target for comparable properties with hydraulic or pozzolanic properties as Portland cement. This study investigates the replacement of different sizes of bottom ash into Portland cement by reducing the content of Portland cement and examined the mechanism between bottom ash (BA) and Portland cement. A cement composite developed by 10% replacement with 1, 7, 14, and 28 days of curing and exhibited excellent mechanical strength on day 28 (34.23 MPa) with 63 mm BA. The porous structure of BA results in lower density as the fineness particles size contains high specific surface area and consume high quantity of water. The morphology, mineralogical, and ternary phase analysis showed that pozzolanic reaction of bottom ash does not alter but complements and integrates the cement hydration process which facilitate effectively the potential of bottom ash to act as construction material.

Nitroxides as reaction intermediates

1982 ◽  
Vol 60 (12) ◽  
pp. 1414-1420 ◽  
Author(s):  
Hans Gunter Aurich
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Isopropyl Alcohol ◽  
High Reactivity ◽  
Reaction Intermediates ◽  
Reaction Products ◽  
Nitronyl Nitroxide ◽  
Reaction Conditions ◽  
Spin Resonance ◽  
Secondary Reactions

Vinyl nitroxides 4 are obtained by oxidation of the nitrones 3, as was shown by esr studies and by identification of the reaction products. The formation of 4d–f is even observed in oxidation of the hydroxylamines 1d–f, nitroxides 2d–f and nitrones 3d–f being the intermediates. The high reactivity of the vinyl nitroxides 4 at their β-position is illustrated by the reactions of 4a with various compounds affording the nitroxides 7–10, respectively. Compound 4c reacts with its precursor 3c to give 11, 12, or 13, depending on the reaction conditions. From oxidation of 3a, c, and e the dimerization products 5a, c, and e, respectively, could be isolated. Whereas further oxidation of 5d yields 6d, the acyl nitroxides 14a and c are formed in the oxidation of 5a and c, respectively.The formation of quinone 23 in the reaction of 2-methyl-2-nitrosopropane with potassium tert-butoxide in isopropyl alcohol in the presence of oxygen is discussed. The nitroxide 20 has been detected in the reaction mixture. Imines 24 react with nitrosobenzene giving nitroxides 26. These are further oxidized by nitrosobenzene to afford nitrones 27. Whereas 27a and b could be isolated, 27c and d undergo further reaction yielding the diimines 30c and d along with dinitrone 29.The formation and reactions of imino nitroxides 31 and of the nitronyl nitroxide 41 are discussed. Electron spin resonance studies revealed the high reactivity of the imidazolyl-1,3-dioxides 46 and the imidazolyl-1-oxides 50, which easily form radicals 47–49 and 51, respectively, which are derived from secondary reactions.

The Feasibility of Using Micro Silica Sand Powder as Partial Replacement of Cement in Production of Roller Compacted Concrete

2021 ◽  
Vol 1021 ◽  
pp. 21-34
Author(s):  
Zahraa Alaa M.A. Ali Khan ◽  
Zena K. Abbas
Keyword(s):  
Portland Cement ◽  
Minimum Cost ◽  
The Other ◽  
Silica Sand ◽  
Engineering Properties ◽  
Crushed Stone ◽  
Partial Replacement ◽  
Roller Compacted Concrete ◽  
Water Curing ◽  
Micro Silica

Roller compacted concrete (RCC) is a special type of concrete with zero or even negative slump consistency. In this work, it had aimed to produce an RCC mix suitable for roads paving with minimum cost and better engineering properties so, different RCC mixes had prepared i.e. (M1, M2, M3, and M4) using specified percentages of micro natural silica sand powder (SSP) as partial replacement of (0%, 5%, 10%, and 20%) by weight of sulfate resistant Portland cement. Additionally, M-sand, crushed stone, filler, and water had been used. The results had obtained after 28 days of water curing. The control mix (M1) had satisfied the required f ‘c with accepted results for the other tests. M2 mix with SSP of 5% had achieved the highest results. The f ’c for sawed cubes of (10*10*10) cm had increased by 2.26% and 3.16% when tested in directions (ꓕ and //) to the direction of loading respectively. R results for sawed prisms of (38*10*10) cm had increased by 8.78% and 8.43% when tested on top and bottom faces respectively. The density had increased by 1.04% while the absorption and volume of permeable voids had decreased by 8.11% and 7.83% respectively. The UPV results had also increased by 2.44% and 0.81% for cubes and prisms respectively when compared to the control mix. M3 mix with SSP of 10% had also achieved satisfactory results when compared to the control mix.

scholarly journals Structural Use of Expanded Polystyrene Concrete

2020 ◽  
Vol 5 (6) ◽  
pp. 1131-1138
Author(s):  
Adeniran Jolaade ADEALA ◽  
Olugbenga Babajide SOYEM
Keyword(s):  
Environmental Pollution ◽  
Lightweight Concrete ◽  
Physical And Mechanical Properties ◽  
Consumer Products ◽  
Expanded Polystyrene ◽  
Engineering Properties ◽  
Partial Replacement ◽  
Construction Companies ◽  
Fine Aggregates ◽  
Concrete Matrix

Expanded polystyrene (EPS) wastes are generated from industries and post-consumer products. They are non-biodegradable but are usually disposed by burning or landfilling leading to environmental pollution. The possibility of using EPS as partial replacement for fine aggregates in concrete has generated research interests in recent times. However, since the physical and mechanical properties of EPS are not like those of conventional fine aggregates, this study is focussed on the use of EPS as an additive in concrete while keeping other composition (sand and granite) constant. Expanded polystyrene was milled, the bulk density of EPS was 10.57kg/m3 and particle size distributions were determined. Engineering properties of expanded polystyrene concrete were determined in accordance with BS 8110-2:1985. The result showed that the amount of expanded polystyrene incorporated in concrete influence the properties of hardened and fresh concrete. The compressive strengths of 17.07MPa with 5 % expanded polystyrene concrete at 28 days for example can be used as a lightweight concrete for partitioning in offices. Incorporating expanded polystyrene granules in a concrete matrix can produce lightweight polystyrene aggregate concrete of various densities, compressive strengths, flexural strengths and tensile strengths. In conclusion, this reduces environmental pollution, reduction in valuable landfill space and also for sustainability in construction companies

Enhanced Catalytic Performance of the FCC Catalyst with an Alumina Matrix Modified by the Zeolite Y Structure-Directing Agent

2019 ◽  
Vol 58 (14) ◽  
pp. 5455-5463
Author(s):  
Mengjie Xie ◽  
Yifang Li ◽  
Ubong Jerome Etim ◽  
He Lou ◽  
Wei Xing ◽  
...  
Keyword(s):  
Zeolite Y ◽  
Catalytic Performance ◽  
Alumina Matrix ◽  
Structure Directing Agent ◽  
Fcc Catalyst

Quantitative Characterization of Particle Shape of FCC Catalysts by Image Analysis

2001 ◽  
Vol 7 (S2) ◽  
pp. 1086-1087
Author(s):  
Zhengmin Li ◽  
Xingzhong Xu ◽  
Jinghe Yang ◽  
Xiuling Xu ◽  
Weijun Yu ◽  
...  
Keyword(s):  
Particle Shape ◽  
Glass Slide ◽  
Oil Refinery ◽  
Quantitative Characterization ◽  
Shape Factors ◽  
Fcc Catalyst ◽  
Fluidized Catalytic Cracking ◽  
Attrition Resistance ◽  
Fcc Catalysts

In the fluidized catalytic cracking (FCC) unit of oil refinery, the attrition resistance of FCC catalysts is affected by particle shape. Although some sophisticated methods, such as Fractal dimension and Fourier analysis, have been introduced to particle shape analysis, most of them are used to assess the shape of individual particle. It is difficult to be used as a means of powder quality control in the course of application and production of FCC catalysts. So three shape factors, i.e. Short/long ratio (S), Roundness (R) and Concavity (C), are applied to characterize them in three different aspects.A small quantity of FCC catalyst powders were spread on a glass slide M and a thin layer of glue was spread on another glass slide N, then all the particles on slide M were sprinkled on slide N by vibrating manually up and down, in the meantime moving back and forth more than 10 times.

scholarly journals Suitability of Scoria as Fine Aggregate and Its Effect on the Properties of Concrete

2019 ◽  
Vol 11 (17) ◽  
pp. 4647 ◽  
Author(s):  
Warati ◽  
Darwish ◽  
Feyessa ◽  
Ghebrab
Keyword(s):  
Construction Materials ◽  
Energy Utilization ◽  
Engineering Properties ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Test Results ◽  
River Sand ◽  
Conventional Concrete ◽  
Efficient Energy ◽  
Concrete Production

The increase in the demand for concrete production for the development of infrastructures in developing countries like Ethiopia leads to the depletion of virgin aggregates and high cement demand, which imposes negative environmental impacts. In sustainable development, there is a need for construction materials to focus on the economy, efficient energy utilization, and environmental protections. One of the strategies in green concrete production is the use of locally available construction materials. Scoria is widely available around the central towns of Ethiopia, especially around the rift valley regions where huge construction activities are taking place. The aim of this paper is therefore to analyze the suitability of scoria as a fine aggregate for concrete production and its effect on the properties of concrete. A differing ratio of scoria was considered as a partial replacement of fine aggregate with river sand after analyzing its engineering properties, and its effect on the mechanical properties of concrete were examined. The test results on the engineering properties of scoria revealed that the material is suitable to be used as a fine aggregate in concrete production. The replacement of scoria with river sand also enhanced the mechanical strength of the concrete. Generally, the findings of the experimental study showed that scoria could replace river sand by up to 50% for conventional concrete production.

SUSTAINABILITY IMPLICATIONS OF THE USE OF HYBRID POLYVINYL ALCOHOL FIBRE-REINFORCED FERROCEMENT AND FLY ASH

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Vanissorn Vimonsatit ◽  
Wahidul K. Biswas
Keyword(s):  
Fly Ash ◽  
Polyvinyl Alcohol ◽  
Sustainability Assessment ◽  
Construction Materials ◽  
Economic Benefits ◽  
Engineering Properties ◽  
Partial Replacement ◽  
Bottom Line ◽  
Polyvinyl Alcohol Fibre ◽  
Alcohol Fibre

Extensive research has been conducted on the use of fly ash as a partial replacement of cement in order to promote the sustainable use of cement. Most of these research has focused on the investigation of the cementitious properties of the blended cement and the engineering properties of the end products, such as fly ash concrete. The sustainability benefit of using fly ash is often qualitatively perceived without any quantitative assessment. A recent study on the performance of hybrid polyvinyl alcohol fibre-reinforced ferrocement (HPVAF) shows that adding moderate amounts of fly ash in the mixes could maintain the ultimate flexure and tensile strength of HPVAF. The increased service life/durability and the use of FA up to a 25% replacement for cement in HPVAF not only conserve virgin resources for producing energy-intensive construction materials but also avoid associated environmental impacts due to the manufacturing of these materials. This certainly offers socio-economic benefits in terms of cost saving, enhance affordability and guaranteed material supply for the people both in current and future generations. Life cycle sustainability assessment (LCSA) was conducted to determine these triple bottom line benefits associated with the use of HPVAF and FA in building construction.

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