Author: J. S. West, C. J. Larosche, B. D. Koester, J. E. Breen, and M. E. Kreger | Size: 5.5 MB | Format:PDF | Publisher: University of Texas at Austin | Year: 1999 | pages: 186
Durability design requires an understanding of the factors influencing durability and the measures necessary to improve durability
of concrete structures. The objectives of this report are to:
1. Survey the condition of bridge substructures in Texas;
2. Provide background material on bridge substructure durability; and
3. Review durability research and field experience for post-tensioned bridges.
A condition survey of existing bridges in Texas was used to identify trends in exposure conditions and common durability
problems. The forms of attack on durability for bridge substructures in Texas are reviewed. Basic theory for corrosion of steel in
concrete is presented, including the effect of cracking. Corrosion protection measures for post-tensioned concrete are presented.
Literature on sulfate attack, freeze-thaw damage, and alkali-aggregate reaction is summarized. Literature on the field performance
of prestressed concrete bridges and relevant experimental studies of corrosion in prestressed concrete is included. Crack prediction
methods for prestressed concrete members are presented.
This report is part of Project 0-1405, “Durability Design of Post-Tensioned Bridge Substructure Elements.” The information in
this report was used to develop the experimental programs described in Research Reports 1405-2 and 1405-3 and in the preparation
of durability design guidelines in Report 1405-5.
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Carbon dioxide uptake in demolished and crushed concrete
Author: Christian J. Engelsen, Jacob Mehus, Claus Pade and Dag Henning Sæther | Size: 1.1 MB | Format:PDF | Publisher: Norwegian Building Research Institute | Year: 2005 | pages: 38 | ISBN: 82-536-0900-0
Recycled Concrete Aggregates (RCA) produced in the Nordic countries was summarized and its
scenario applications with regard to the grain size were described. The CO2 uptake to different crushed
concrete types was then measured by conducting extensive accelerated laboratory tests, in order to
document any differences in the uptake rate between the different crushed concrete samples.
Furthermore, the maximum uptake of CO2 within reasonable testing time in laboratory was also
determined.
The annually volumes of concrete rubble generated in the Nordic countries, except for Island, was
estimated to be in the range of 0.6 to 1.2 million ton. From these concrete rubble volumes, the
production of RCA were calculated to be in the range of 0.2 to 1.0 million ton corresponding to a
recycling level of 30-90 %. In Norway, Finland and Sweden the current recycling level is at 30, 50 and
60 % respectively. However, these countries reported that the target recycling level is 70 % by the end
of 2010. The current recycling level in Denmark was reported to be 90 % and is expected to be the
same by the end of 2010. In Finland, however, a major increase in the concrete rubble generation
(from 45 % to 60 %) as well as the expected increase in the recycling level results in a major increase
in the RCA production by the end of 2010. The annual concrete rubble generation in Island is
approximately 50 000 ton which is landfilled.
In the laboratory different concrete mixes were tested for CO2 uptake. After hardening the mixes were
crushed into different grain sizes. It was found that 60-80 % of the CO2 released released during
calcination is reabsorbed to the concrete mixtures with w/c of 0.6 or higher for the grain size of 1-8
mm within 20-35 days of exposure. Furthermore, the calculation showed that 60-90 % of the total CaO
in the same samples was carbonated. Determination of the total carbon in the carbonated samples by
total combustion and CO2 detection showed reasonable agreement with the measured CO2 uptake.
The w/c ratio was found to be crucial as expected. Comparison of the mixes with the w/c ratios from
0.4 up to 0.75 showed large differences as the highest w/c ratio gave the highest carbonation rate.
Thus, it was found that more than 90 % and less than 10 % of the CO2 was absorbed within the first 50
hours of exposure for the mixes with w/c of 0.75 and 0.4 respectively testing samples with grain size
of 1-8 mm. Coarser aggregate samples carbonated significantly slower.
Although the reaction kinetics varied due to the changing CO2 partial pressure in the exposure
desiccators, this test setup provided a fairly rapid quantification of the carbonation rate in between
different concrete mixes. The tests also gave a realistic measurement of the total CO2 uptake for the
different samples which can support the documentation of concrete carbonation during service life and
secondary use.
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Construction Management in Japan - notes from a short visit
Author: Odd Sjøholt | Size: 0.3 MB | Format:PDF | Publisher: Norwegian Building Research Institute | Year: 1999 | pages: 59 | ISBN: 82-536-0665-6
This report gives some informal notes on management of construction in Japan, as seen by the eyes of myself, the Norwegian author, after a two-week study tour in May-June 1999. The two first chapters describe my understanding in forehand, and were written before the travel and sent to the people I was going to visit.
The introductory chapter ZZ is summarising the management topics my Institute and especially myself have concentrated on since the 1960’s. It clearly shows how different epochs of management focus topics have passed by over time. It should also indicate how a research institute as a foundation in a small country as Norway is central in developing practical management tools and applications in direct co-operation with the individual actors in the construction industry itself.
The following chapter ZZ describes the knowledge of Japan achieved before the visit. It includes a listing and short abstract from literature on construction management in Japan, which I have read and used as a baseline for the chosen study topics. I have focussed on the Japanese differences from concepts and methods known from Norway and other Western Countries. Little information was found in the literature about any systematic R&D on construction management concepts, aiming at increasing the effectivity and efficiency as such. The chapter ends with a description and listing of topics for further questioning during the visit.
ZZ is a chapter describing day by day the performed visits. The minutes for each day indicate all the main topics being treated. Each host provided information about his working area, and somewhat illustrated other relevant areas. The presentations given were of great value, and extracts is utilised directly or indirectly in the report. Discussions were deepest in the smaller fora, that means in the institutes and universities. I met representatives of many parts of construction, but was missing subcontractors and mediumsised enterprises. As the hosts represented different actors or interests in the construction sector the information gathered supplemented each other rather well.
ZZ is a chapter where a great deal of my prepared questions are
enlightened. But also quite a lot of questions or details were not discussed, due to the limited
allowable time or the actual fora I met. One other important reason is of course that many
problems seen from a Norwegian angle are not relevant at the time being in Japan – and vice
versa. The chapter is structured under a great number of headlines, each representing a sort of
conclusion or finding. An overview based on adjusted headlines is as follows:
CONTENDS:
Preface......................................................................................................................................3
Content.....................................................................................................................................4
1. Summary........................................................................................................................5
2. Norwegian baseline for the study ..................................................................................8
3. Preparations and studies before the travel ...................................................................10
4. Visits, presentations and excursions............................................................................19
5. Study results and conclusions ......................................................................................44
6. References, literature....................................................................................................53
Appendix. Programme for Mr. Odd Sjøholt .........................................................................55
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Guide for the use of stainless steel reinforcement in concrete structures
Author: Gro Markeset, Steen Rostam and Oskar Klinghoffer | Size: 2.5 MB | Format:PDF | Publisher: Norwegian Building Research Institute | Year: 2006 | pages: 68 | ISBN: 82-536-0926-4
Premature deterioration of concrete buildings and infrastructure due to corrosion of reinforcement
is a severe challenge, both technically and economically. Repair-work on the public transportation
infrastructure are causing significant inconveniences and delays for both the industry and the
general public, and are now recognized as a substantial cost for the society.
In recent years there has been an increasing interest in applying stainless steel reinforcement in
concrete structures to combat the durability problems associated with chloride ingress. However,
the use of stainless steel reinforcement (SSR) has so far been limited mainly due to high costs and
lack of design guides and standards.
In 2004 a Scandinavian group was established to cope with these challenges and a Nordic
Innovation Centre project: “Corrosion resistant steel reinforcement in concrete structures
(NonCor)” was formed.
The present report; “Guide for the use of stainless steel reinforcement in concrete structures”, is the
final document of this project. The scope of this Guide is to increase the durability and service life
of concrete structures exposed to corrosive environments by focusing on two issues:
• Eliminating reinforcement corrosion by examining the core of the problem, i.e. the
reinforcement itself
• Overcoming the technical knowledge gap for application of stainless steel reinforcement in
concrete structures
The foreseen users of this Guide are:
• All parties involved in planning, design and construction of concrete structures to be
exposed to corrosive environments, - such as marine structures, coastal-near structures and
structures exposed to chloride based de-icing salts
• Owners and Clients who want to reduce or solve the corrosion problem for reinforced
concrete structures, in order to obtain a long service life with minimal maintenance
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Size effect is known as a relative change (decrease) of the structural properties (peak
resistance, ductility, etc.) when the structure size increases. In quasi brittle materials such as
concrete, this is a recognized phenomenon.
For the concrete material most focus on size effect has been connected to the tensile states of
stress. After the development of the Fictitious Crack Model (Hilleborg et al 1976), there have
been large research activities within the field of fracture mechanics applied for concrete,
particular for tensile states of stress. Based on this work it is now generally accepted that
tensile failure is localized to a limited zone and that this failure localization is the source of
the so-called size effect. In the new Eurocode 2 this size effect is implemented for punching
and shear using a size factor k= 1+ 200 / d , where d is the member depth in mm.
Compressive failure is, as in tensile failure, found to be localized to certain zones and gives
rise to a size effect (Hillerborg (1988), Bažant (1989), Markeset (1993, 1994), Markeset and
Hillerborg (1995), Bigaj and Walraven (1993), Janson and Shah (1997), Walraven (2007),
van Mier (2007)).
The compressive behaviour of concrete is one of the fundamental parameters of structural
design as most load-bearing concrete elements, such as beams, columns and slabs, experience
compressive strain gradients where the compressive strain at the critical section is in the postpeak
(softening regime) of the stress-strain curve at failure. The presently used codes of
practice do not limit their application field to some selected range of member dimensions
although experimental studies have shown that size effect of concrete loaded in compression
exists.
In this report the size effect of compressive failure of concrete members exposed to uniaxial
compression as well as compressive strain gradients is discussed.
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Author: Park, T. and Gamble, W | Size: 30 MB | Format:PDF | ISBN: 0471348503
Comprehensive, up–to–date coverage of reinforced concrete slabs–from leading authorities in the field.
Offering an essential background for a thorough understanding of building code requirements and design procedures for slabs, Reinforced Concrete Slabs, Second Edition provides a full treatment of today′s approaches to reinforced concrete slab analysis and design
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Quote:thesis concerning the modeling of piles with the ANSYS finite element code
download links,
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NA to BS EN 1991-1-2:2002
UK National Annex to Eurocode 1: Actions on structures –
Part 1-2: General actions – Actions on structures exposed to fire
This National Annex gives:
a) the UK decisions for the Nationally Determined Parameters
described in the following subclauses of BS EN 1991-1-2:2002:
• 2.4 (4)
• 3.1 (10)
• 3.3.1.2 (1)
• 3.3.1.3 (1)
• 3.3.2 (2)
• 4.2.2 (2)
• 4.3.1 (2)
b) the UK decisions on the status of BS EN 1991-1-2:2002
informative annexes.
NA to BS EN 1991-1-6:2005
UK National Annex to Eurocode 1: Actions on structures –
Part 1-6: General actions – Actions during execution
NA to BS EN 1991-2:2003
UK National Annex to Eurocode 1: Actions on timber structures – Part 2: Traffic loads on bridges
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Advanced civil infrastructure materials: Science, mechanics and applications
Edited by H Wu, Wayne State University, USA
- a valuable reference for researchers and practitioners in the construction industry
- essential reading for graduate and undergraduate students of civil engineering
- written by an expert pannel
In recent decades, material development in response to a call for more durable infrastructures has led to many exciting advancements. Fiber reinforced composite designs, with very unique properties, are now being explored in many infrastructural applications. Even concrete and steel are being steadily improved to have better properties and durability.
Advanced civil infrastructure materials provides an up-to-date review of several emerging construction materials that may have a significant impact on repairs of existing infrastructures and/or new constructions. Each chapter explores the ‘materials design concept’ which leads to the creation of advanced composites by synergistically combining two or more constituents. Such design methodology is made possible by several key advancements in materials science and mechanics. Each chapter is concluded with selective examples of real world applications using these advanced materials. This includes relevant structural design guidelines and mechanics to assist readers in comprehending the uses of these advanced materials.
The contributors are made up of renowned authors who are recognized for their expertise in their chosen field. Advanced civil infrastructure materials will be of value to both graduate and undergraduate students of civil engineering, and will serve as a useful reference guide for researchers and practitioners in the construction industry.
Contents
Advanced concrete for use in civil engineering
S Mindess, University of British Columbia, Canada
- Introduction
- What is modern advanced concrete? Materials: Portland cements; Aggregates; Chemical admixtures; Mineral admixtures
- Modern advanced concretes: High strength concretes; Ultra high strength concretes; Fibre reinforced concretes; Self-compacting concrete; High durability concrete; Polymer modified concretes; ‘Green’ concrete
- Conclusions
- Sources of further information
- References
Advanced steel for use in civil engineering
C W Roeder, University of Washington, USA and M Nakashima, Kyoto University, Japan
- Introduction
- Issues of concern
- New developments: New materials; New components; New systems
- Sample structures
- Future trends
- Sources of further information
- Acknowledgments
- References
Advanced cement composites for use in civil engineering
H C Wu, Wayne State University, USA
- Introduction: Infrastructure degradation; Material issues
- Performance driven design with fiber reinforcement: Composite behaviour; Significance of performance driven design approach
- Composite engineering: Matrix design (toughness control); Unit weight design (density contol); Workability design (rheology control); Interface design (bond control)
- Advanced cementitious composites: Short fiber composites; Continuous fiber composites; Durability
- Engineering applications: Structural retrofit for compressive strength
- Conclusions
- Acknowledgments
- References
Advanced fibre-reinforced polymer (FRP) composites for use in civil engineering
J F Davalos, West Virginia University, USA, P Qiao and L Shan, University of Akron, USA
- Introduction
- Manufacturing process by pultrusion
- Material properties and systematic analysis and design: Constituent materials and ply properties; Laminated panel engineering properties and Carpet plots; Member stiffness properties; Mechanical behaviours of FRP shapes; Equivalent analysis of FRP cellular decks; Macro-flexibility analysis of deck-and-stringer bridge systems
- Design guidelines and examples: Design guidelines for FRP shapes; Design examples; Example 3: design of an FRP deck-and-stringer bridge
- Conclusions
- Acknowledgments
- References
Rehabilitation of civil structures using advanced polymer composites
V M Karbhari, University of California, USA
- Introduction
- Rehabilitation and FRP composites
- Materials and manufacturing processes: Materials overview; Manufacturing processes
- Characteristics and properties
- Applications
- Future trends
- References
Advanced engineered wood composites for use in civil engineering
H J Dagher, University of Maine, USA
- Introduction: Enabling advances in science and engineering; AEWC significance
- Characteristics and properties: Lessons from the past: compatibility and durability; FRP versatility can overcome compatibility and durability problems; Examples of mechanical properties improvements
- Applications: FRP-glulams; FRP-reinforced wood-plastic composites; FRO-reinforced sheathing panels
- Conclusions
- References
Sustainable materials for the built environment
J Harrison, TecEco Pty Ltd, Australia
- Introduction: Major themes; Theme statement
- The current situation
- Sustainability
- The earth’s natural systems: Carbon and oxygen flows; Biomimicry
- The impact of current technology: Impacts; Combined impacts
- Managing change: The need for change; Getting over barriers; The economics of change towards sustainability; Drivers for change; The process of change
- Reducing the environmental impact of technology: Managing waste efficiently
- Sustainable materials for the built environment: Lighter weight materials; Embodied energies and emissions; Lifetime energies; Heat-absorbing or releasing materials; Using waste in new materials; Healthy materials; Using recycled materials; More durable materials; Recycled materials
- Creating more sustainable production: eco-cements: Sequestration processes; The practicalities of sequestration; Other sustainable binders
- Making sustainability profitable: Entrepreneurs and innovation; The role of government; The role of professionals
- Conclusion
- Appendix: suggested policies for governments for a sustainable built environment
- References
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Corrosion of reinforced concrete structures has been a significant problem for many state and transportation agencies since the application of deicing salts was introduced. Much research has been conducted to develop corrosion protection systems that can prolong the life span of reinforced concrete structures. CDOT has several routine and experimental measures to prevent corrosion of the rebar including epoxy-coated rebar, calcium nitrite admixture, organic corrosion inhibitors, a thick cover of quality concrete, and a waterproofing membrane covered by an asphalt overlay.
An extensive literature review was performed to collect information on various corrosion protection systems that have been used in the U.S. and around the world. Current CDOT practices in terms of corrosion protection measures were reviewed. A draft inspection plan for Colorado’s bridge structures was proposed. This plan could be further refined in the future to evaluate the performance of routine measures and experimental measures for corrosion protection. Field inspections were conducted for two sets of bridges (total of 16 bridges). One set is for evaluating the corrosion damage in some bridges in the TREX project (a major ongoing highway project in the Denver area), and the other set is for the inspection of various corrosion protection systems that have been used in Colorado. The seven TREX bridges inspected in this project used three corrosion protection methods: epoxy-coated rebar, asphalt overlay, and membranes. Corrosion of steel and corrosion-induced damage in concrete occurred in all bridges except the Dry Creek Bridge, which is relatively new. The degree of corrosion is quite high. Nine other bridges with different corrosion protection systems were inspected to study the effectiveness of these protection methods.
Based on the inspection results, we can conclude that, in general, corrosion of steel bars in concrete is an existing problem for highway bridges in Colorado. The extent of the problem is quite significant. Among the three most commonly used protection systems (epoxy-coated rebar, corrosion inhibitors, and membranes), the results obtained in the present study are inconclusive for determining which system is better.
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