New Types of High Performance Concretes – Potentials for Innovations in Concrete Construction

2011 ◽  
pp. 43-58 ◽  
Author(s):  
Harald S. Müller ◽  
Michael Haist
Keyword(s):  
High Performance ◽  
Concrete Construction

Applying Research on Testing Compressive Strength of High Performance Concrete with Rebound Method

2012 ◽  
Vol 452-453 ◽  
pp. 106-109
Author(s):  
Zheng Jun Wang ◽  
Felix Zhao
Keyword(s):  
Compressive Strength ◽  
Concrete Structure ◽  
High Performance ◽  
High Performance Concrete ◽  
Cement Concrete ◽  
Construction Quality ◽  
Concrete Construction ◽  
Estimation Models

In order to grasp timely and accurately quality of high performance concrete, detection of compressive strength of high performance concrete can be non-destructively, rapidly and accurately tested that is very testing index. The paper did some research on compressive strength of high performance concrete applying redound method that it established several estimation models between rebound value and compressive strength. Experiment shows that rebound method can effetely test compressive strength of high performance concrete. Construction quality of Cement concrete structure can timely grasp applying the method.

Rapid Bridge Replacement – Learning from the USA

2018 ◽  
Author(s):  
Charlotte Murphy
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Precast Concrete ◽  
Accelerated Bridge Construction ◽  
Ultra High Performance Concrete ◽  
Concrete Construction ◽  
The Usa ◽  
The Uk ◽  
Concrete Elements ◽  
Innovative Techniques

<p>The IStructE Pai Lin Li Travel Award funded the author for an investigation into current practice precast concrete construction in the USA. The Federal Highways Administration (FHWA) in the USA has invested heavily in research into precast concrete construction through its Accelerated Bridge Construction (ABC) programme. The FHWA’s research has had a focus on innovative techniques for joining structural precast concrete elements together.<p>Grouted splice couplers and Ultra-High Performance Concrete are the two key enabling techniques that were investigated in this research. The replacement of 6 36m span bridges over Interstate 78 in Pennsylvania used these techniques and completed each bridge replacement in 40 days. This paper investigates the development of these techniques, the benefits they could have on the UK construction industry and what actions need to be taken to realise those benefits.

Structural design criteria for road bridges made of UHPC large prefabricated parts - approaches to possible CO2 savings potential in bridge construction

2021 ◽  
Author(s):  
Michael Olipitz
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Side Wall ◽  
Concrete Bridges ◽  
Material Structure ◽  
Bridge Construction ◽  
Concrete Construction ◽  
Girder Bridges ◽  
The One

<p>The future development of girder bridges is determined by the goals of more sustainable and more resource-efficient forms of construction, which can be achieved by optimizing material, structure and manufacture. The practice of early, costly repairs or replacement buildings, which has been common in reinforced concrete construction for decades, allows the realization to mature that the reinforced concrete material for heavily exposed structures in the infrastructure sector must be replaced by a more efficient material and its construction method. In materials research in the 21st century, the UHPC (ultra high performance concrete) has become the preferred option for constructive use in bridge construction and, when used appropriately, offers many possibilities</p><p>The UHPC combines the advantages of concrete construction with those of steel construction and is also more durable. The main focus is on the structural detailing and application of UHPC prefabricated parts appropriate to the material and the associated reduction in susceptibility to corrosion, the main disadvantage of concrete bridges.</p><p>The use of <i>UHPC-bridgefamily</i><i>Integral</i><i> </i>in bridge construction should, in addition to a possible longer service life, primarily enable resource savings and the associated savings in CO2 consumption compared to reinforced concrete construction. For an example of 170m long span bridge structure, the article shows a comparison between the reinforced concrete construction and the UHPC construction, both in terms of mass and energy consumption.</p><p>The structural optimization of the flat UHPC side wall is done on the one hand by adapting the panel thickness and by making targeted openings. In the following, some of the construction-specific details are presented, such as the fixture and the joint detail for decoupling the roadway plate and the longitudinal structure. The presented construction of the UHPC-bridgefamilyIntegral is intended on the one hand to show the optimization possibilities for girder bridges in the medium span range and on the other hand the advantages of UHPC in terms of sustainability and resource efficiency as well as the possibilities of an aesthetic formulation for future applications.</p>

A High Performance Energy Analyzer for Use in Electron Scanning Microscopy

1969 ◽  
Vol 27 ◽  
pp. 14-15
Author(s):  
A. V. Crewe ◽  
M. Isaacson ◽  
D. Johnson
Keyword(s):  
High Performance ◽  
Vertical Plane ◽  
Median Plane ◽  
Electron Gun ◽  
Uniform Field ◽  
Loss Mechanism ◽  
Electron Scanning Microscopy ◽  
Sector Type ◽  
Double Focusing ◽  
Electron Energy Loss

A double focusing magnetic spectrometer has been constructed for use with a field emission electron gun scanning microscope in order to study the electron energy loss mechanism in thin specimens. It is of the uniform field sector type with curved pole pieces. The shape of the pole pieces is determined by requiring that all particles be focused to a point at the image slit (point 1). The resultant shape gives perfect focusing in the median plane (Fig. 1) and first order focusing in the vertical plane (Fig. 2).

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering

1970 ◽  
Vol 28 ◽  
pp. 360-361
Author(s):  
John W. Coleman
Keyword(s):  
Boundary Conditions ◽  
High Performance ◽  
Force Fields ◽  
Optical Design ◽  
Direct Conversion ◽  
Design Engineering ◽  
Design Data ◽  
Scalar Potentials ◽  
Geometric Elements ◽  
At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.

Prospects for convergent beam electron diffraction with a 200kV cold field-emission transmission electron microscope

1991 ◽  
Vol 49 ◽  
pp. 466-467
Author(s):  
J W Steeds ◽  
R Vincent
Keyword(s):  
Field Emission ◽  
High Performance ◽  
Small Diameter ◽  
Convergent Beam Electron Diffraction ◽  
Zone Axis ◽  
Medium Voltage ◽  
Transmission Electron ◽  
Good Crystallinity ◽  
Special Modification ◽  
Convergent Beam

We review the analytical powers which will become more widely available as medium voltage (200-300kV) TEMs with facilities for CBED on a nanometre scale come onto the market. Of course, high performance cold field emission STEMs have now been in operation for about twenty years, but it is only in relatively few laboratories that special modification has permitted the performance of CBED experiments. Most notable amongst these pioneering projects is the work in Arizona by Cowley and Spence and, more recently, that in Cambridge by Rodenburg and McMullan.There are a large number of potential advantages of a high intensity, small diameter, focussed probe. We discuss first the advantages for probes larger than the projected unit cell of the crystal under investigation. In this situation we are able to perform CBED on local regions of good crystallinity. Zone axis patterns often contain information which is very sensitive to thickness changes as small as 5nm. In conventional CBED, with a lOnm source, it is very likely that the information will be degraded by thickness averaging within the illuminated area.

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