Fiber Reinforced Fly Ash Concrete and Extreme Fires

2016 ◽  
Vol 722 ◽  
pp. 12-17 ◽  
Author(s):  
Miroslav Broucek ◽  
Michal Sejnoha ◽  
Pavel Reiterman
Keyword(s):  
Fly Ash ◽  
Temperature Distribution ◽  
Large Scale ◽  
Steel Fibers ◽  
Experimental Program ◽  
Fire Exposure ◽  
Concrete Panels ◽  
Fly Ash Concrete ◽  
Exposure Temperature ◽  
Fire Curve

The paper presents results from two large scale experiments on six concrete panels reinforced with steel fibers or bars obtained during an extensive experimental program aimed at possible application of cement reduced (fly ash replaced) concrete in the production of precast segmental linings for tunnels created by TBM. In particular, this paper focuses on the comparison of fire resistance of enhanced mixtures loaded by the modified RWS fire curve. The results from the experiments include spalling, overall damage of the surface, deformations during the fire exposure, temperature distribution and residual strength of the tested panels.

STUDY OF THE COMPOSITE ACTION OF HOLLOWCORE PANELS USED IN GIRDER-SLAB SYSTEM

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Nathalie Roy ◽  
Serge Parent ◽  
Mélissa Barrière
Keyword(s):  
Prestressed Concrete ◽  
Large Scale ◽  
Steel Structure ◽  
Experimental Program ◽  
Steel Beams ◽  
Composite Action ◽  
Concrete Panels ◽  
Current Design ◽  
Main Components ◽  
Hot Rolled

Floor construction with precast hollowcore panels produced by Lafarge Precast Edmonton results in a commonly used girder-slab system. Continuity between the elements is ensured by bent rebars and shear studs. Once all these elements are installed, a structural concrete is poured between the reinforced concrete panels and over the entire floor. The extent of composite action between the rigid diaphragm and the steel beams is not known. Therefore, its potential benefit is not taken into account in the current design procedures for the steel structure. The main components of this research project are the following: an experimental program consisting of a series of 6 large-scale shear tests were carried out. The outcome of this research shows that there is a potential for a composite action between a hollowcore plank and a standard hot rolled W shape. It was found that there is enough confinement to develop the steel stud strength when the beam is connected to the precast prestressed concrete panels using a 1/2" shear stud embedded between the planks and under two to three inches of concrete topping.

scholarly journals Effect of High Volume Flyash on Fiber Strengthened Concrete

2019 ◽  
Vol 8 (11) ◽  
pp. 2467-2473
Keyword(s):  
Fly Ash ◽  
Basalt Fiber ◽  
High Volume ◽  
Cementitious Material ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fly Ash Concrete ◽  
High Volume Fly Ash ◽  
Test Outcomes ◽  
The Ideal

Fly Ash (FA) is being utilized as a pozzolonic material when connected as a valuable cementitious material for cement. Fiber Reinforced Concrete (FRC) is a solid having sinewy material which manufactures its helper uprightness. It contains short discrete strands that are reliably scattered and aimlessly arranged. The expansion of Steel Fibers in cement essentially expands its flexural strength; vitality retention limit, malleable conduct before a definitive disappointment, decreased breaking, and improved toughness. Basalt fiber is an elite non-metallic fiber produced using basalt shake dissolved at high temperature. In High Volume Fly Ash Concrete (HVFAC), increment in the amount of cementitious C-S-H stage and calcium aluminium hydrates improves the long haul qualities and lessens the porousness. Therefore improves the solidness properties. The primary point of this examination is to consider the mechanical properties of HVFA cement fortified with half and half filaments. Tests are directed according to the Indian norms and test outcomes are broke down and contrasted and the control example that contains crossover fiber fortified HVFA concrete, HVFA concrete without any strands (non-stringy cement), and Conventional cement. With the fitting understanding of the got outcomes, it is possible to decide the ideal fiber rate in HVFA concrete.

scholarly journals Investigation of Strength Parameters of PVA Fiber-Reinforced Fly Ash-Soil Mixtures in Large-Scale Direct Shear Apparatus

2018 ◽  
Vol 4 (11) ◽  
pp. 2618 ◽  
Author(s):  
Ashkan Gohari Lasaki ◽  
Reza Jamshidi Chenari ◽  
Javad Shamsi Sosahab ◽  
Yaser Jafarian
Keyword(s):  
Fly Ash ◽  
Polyvinyl Alcohol ◽  
Large Scale ◽  
Experimental Program ◽  
Direct Shear ◽  
Fiber Reinforced ◽  
Geotechnical Characteristics ◽  
Soil Mixtures ◽  
Direct Shear Apparatus ◽  
Pva Fiber

Soil reinforcement is an old and still efficient technique in improving soil strength and stiffness properties. Current paper aims at quantifying the effects of different inclusions on mechanical behavior of fiber-reinforced cemented soil. An experimental program was conducted to study simultaneous effects of randomly oriented fiber inclusions and cement stabilization on the geotechnical characteristics of fly ash-soil mixtures. Chamkhaleh sand, polyvinyl alcohol (PVA) fiber, cement and fly ash with some water were mixed and compacted into large scale direct shear apparatus with three equal layers. PVA fibers were randomly distributed in three compacted layers at predetermined weight contents. Direct shear tests were carried out on fly ash-soil specimens prepared with different cement, fly ash and polyvinyl alcohol contents, and 7 different curing periods. Results show that cement increases the strength of the raw fly ash-soil specimens. The fiber inclusion further increases the strength of the cemented and uncemented soil specimens and transforms their brittle behavior to ductile behavior. The fiber reinforcement and distribution throughout the entire specimen results in a significant increase in the strength of fly ash -soil- cement mixtures.

Effect of Internal Activation Using Porous Ceramic Aggregate on Hardness and Pore Structure of Fly Ash Cement Paste

2016 ◽  
Vol 711 ◽  
pp. 95-102 ◽  
Author(s):  
Kazuki Ootaishi ◽  
Phuong Trinh Bui ◽  
Yuko Ogawa ◽  
Kenji Kawai
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Cement Paste ◽  
Porous Ceramic ◽  
Pozzolanic Reaction ◽  
Experimental Program ◽  
Early Age ◽  
Fly Ash Concrete ◽  
Activating Agent ◽  
Sulfate Activation

The utilization of fly ash not only reduces the environmental impact but also improves some mechanical properties and durability of concrete. However, the early-age strength of fly ash concrete is sometimes lower than that of normal concrete due to the slow pozzolanic reaction of fly ash. In recent years, some researchers have suggested alkali or sulfate activation to accelerate the pozzolanic reaction. Some studies have used sodium hydroxide (NaOH) solution, while others have applied potassium sulfate (K2SO4) or sodium sulfate (Na2SO4) as activators which are effective in accelerating the pozzolanic reaction and increasing the strength at early age. On the other hand, the early-age strength of fly ash concrete is also improved by using porous ceramic aggregate (PCA) as an internal curing agent. Therefore, the present study aims at investigating the effect of an internal activating agent using PCA on hardness and pore structure of fly ash cement paste. In the experimental program, PCA immersed in two kinds of solution (K2SO4 and Na2SO4) was placed in the center of specimen with dimension of 21x21x20 mm. In addition, normal aggregate (NS) was used for reference. As a result, internal sulfate activation using PCA improved the hardness of interfacial transition zone (ITZ) between paste and PCA, and reduced the Ca(OH)2 content in cement paste with 40% replacement with fly ash significantly at the age of 1 day, but negligibly at the ages of 7 and 28 days when compared with reference specimen. K2SO4 was more effective in improving hardness of ITZ as an internal activating agent than Na2SO4. Although the total pore volumes of the fly ash cement pastes using PCA imbibing sulfate activators were not reduced at the age of 28 days, their pore volumes with diameters less than 0.05 µm were increased.

Study on the Chloride Contents of Sea Sand in Ningbo

2011 ◽  
Vol 250-253 ◽  
pp. 257-261
Author(s):  
Jun Zhe Liu ◽  
Jian Bin Chen ◽  
Guo Liang Zhang ◽  
Zhi Min He
Keyword(s):  
Fly Ash ◽  
Large Scale ◽  
Fine Aggregate ◽  
Comparison Analysis ◽  
River Sand ◽  
Fly Ash Concrete ◽  
Mortar Strength ◽  
Sea Sand ◽  
Early Strength ◽  
Coastal River

This paper is to study the sand concrete, sand is mixed with sand as fine aggregate in concrete, in recent years by large-scale applications in the coastal areas, especially in Ningbo, a coastal river sand shortage is resolved this problem, coupled with low prices, most of the commercial concrete companies are willing to play down the use of sand instead of river sand, the paper surveys and analyzes the use of sea sand in Ningbo and the physical characteristics of sea sand, on this basis, simulates sand chloride doped, dilute sea sand, not dilute sand sea sand and fly ash concrete mortar strength was measured to analyze the strength of law, by comparison analysis, the presence of chloride in the early strength concrete sand.

scholarly journals Stator Non-Uniform Radial Ventilation Design Methodology for a 15 MW Turbo-Synchronous Generator Based on Single Ventilation Duct Subsystem

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2760
Author(s):  
Ruiye Li ◽  
Peng Cheng ◽  
Hai Lan ◽  
Weili Li ◽  
David Gerada ◽  
...  
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Design Methodology ◽  
Large Scale ◽  
Synchronous Generator ◽  
Axial Direction ◽  
Scale Model ◽  
Element Analysis ◽  
Axial Temperature ◽  
Ventilation Duct

Within large turboalternators, the excessive local temperatures and spatially distributed temperature differences can accelerate the deterioration of electrical insulation as well as lead to deformation of components, which may cause major machine malfunctions. In order to homogenise the stator axial temperature distribution whilst reducing the maximum stator temperature, this paper presents a novel non-uniform radial ventilation ducts design methodology. To reduce the huge computational costs resulting from the large-scale model, the stator is decomposed into several single ventilation duct subsystems (SVDSs) along the axial direction, with each SVDS connected in series with the medium of the air gap flow rate. The calculation of electromagnetic and thermal performances within SVDS are completed by finite element method (FEM) and computational fluid dynamics (CFD), respectively. To improve the optimization efficiency, the radial basis function neural network (RBFNN) model is employed to approximate the finite element analysis, while the novel isometric sampling method (ISM) is designed to trade off the cost and accuracy of the process. It is found that the proposed methodology can provide optimal design schemes of SVDS with uniform axial temperature distribution, and the needed computation cost is markedly reduced. Finally, results based on a 15 MW turboalternator show that the peak temperature can be reduced by 7.3 ∘C (6.4%). The proposed methodology can be applied for the design and optimisation of electromagnetic-thermal coupling of other electrical machines with long axial dimensions.

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