There are numerous construction projects going on all around us everyday, everywhere we go. They are found on the route to work, at our children's elementary schools, on the outskirts of town, or in our neighbors' backyard. All of these structures are going up for some reason or another, they each have their own unique need to fill in society, their own groups or individuals to satisfy.
Construction projects can normally be fit into three principal categories: new structures, remodels and add-ons. New projects are being built with different objectives. Businesses build office buildings, industrial plants, warehouses and factories when existing structures are not sufficient for their needs. Individuals and families oftentimes build new homes with the intent of improving their quality of life; expanding for the growing needs of their family or tastes; because they either they didn't locate a home that they enjoyed, or it was too expensive or that was in the area they needed or desired to move into; or as a means to make more money by investing it in a new structure.
Many times there is no need to completely rebuild your business or home. Some minor changes may be just what the doctor ordered. These changes come in the form of remodeling or adding on. Remodeling consists of taking what is already built and making normally minor changes. These minor changes however usually change the atmosphere of whatever is being built dramatically.
For example, I can still remember how small my grandparent's house was until they had their house remodeled. After it was remodeled, there was much more open space and it was a place that became more pleasant to visit. I still am in unbelief as to how they managed to raise 7 kids in the house before it was remodeled. I am sure that there are many of you that have a family member who has remodeled their home or maybe you have even done so. The point is, remodeling is always being done, especially in many of the older houses that didn't allow for families to grow. This construction project can be fun and even exciting as you are able to see the improvements being made as your home is being remodeled.
Something very similar is taking what you already have and adding on to it. By doing so little remodeling is usually done with the structure that already exists. Most often, one wall may be taken down in order to connect it with the new add on. This technique is normally used when the existing structure no longer is comfortable for those using it.
With so many construction projects going on, there becomes a rise for contracting opportunities. Building opportunities are a must find for contractors. There is a large need for contractors today as many of the older homes are being remodeled and people are beginning to add on to their homes to allow for more space and room to grow.
The best way to find the construction job that your company wants is by finding the largest amount of opportunities to place construction bids. By doing so, you will be able to make the best use out of your time and find the best jobs that will give you the most revenue possible for each project you undertake. Construction leads therefore are one the most important and best ways to find the best projects to bid on.
Thursday, December 23, 2010
There are numerous construction projects going on all around us everyday, everywhere we go. They are found on the route to work, at our children's elementary schools, on the outskirts of town, or in our neighbors' backyard. All of these structures are going up for some reason or another, they each have their own unique need to fill in society, their own groups or individuals to satisfy.
Although underwater concreting has been in use for a long time, development of the technique has mainly proceeded in the areas of concrete placing method and improvements to the construction machinery. The prepacked concrete method, tremie method, concrete pump method, and others are now the representative underwater concreting methods. With all these concreting methods, the essential aim of technological development has been to improve how the concrete is placed and to minimize contact between the water and mortar so as to prevent the concrete from segregating under water.
On the other hand, antiwashout underwater concrete is quite different in concept from the methods mentioned above; the developmenta1aim in this case was improved performance of the fresh concrete. That is, the viscosity of the concrete was increased and its resistance to segregation under the washing action of water was enhanced by mixing an antiwashout admixture with the concrete. The effect of this is not only to greatly improve the reliability of Concrete placed underwater, but it also has remarkable effects on environmental preservation in the construction area. In addition, the earlier tremie and concrete pump placing methods can be adopted for construction.
The specific advantages of antiwashout underwater concrete include the following:
•Compared with ordinary concrete, antiwashout underwater concrete is highly resistant to the washing action of water, and rarely separates even when dropped under water
•Its yield value is small and viscosity high, so the concrete components never segregate and it displays high fluidity.
•As a result of the high fluidity, filling property and self-leveling ability are improved.
•Almost no bleeding occurs.
These qualities are taken full advantage of in work which would be difficult to handle using conventional underwater concrete. This includes work where high reliability is required, work in flowing water, work where water turbidity is restricted due to environmental considerations, and work where construction stretches over a considerable area and good flatness is necessary. On the other hand, however, handling is more difficult than with ordinary concrete, and in order to produce concrete of the required quality and a structure of the required performance, careful consideration of mix proportion, mixing, transport, and placing, etc. is necessary when antiwashout underwater concrete is used.
In particular, when producing the underwater antiwash concrete it is necessary to mix it for longer than ordinary concrete in a mixer large enough to uniformly disperse the antiwashout admixture. Also, when using concrete pumps for placement, it is necessary to design a pumping plan with care as regards pumping equipment, pumping distance, etc., because the pumping resistance is increased by the higher viscosity.
Generally, the contractor shall allow for all necessary measures to monitor and avoid cracking in fresh hydrating concrete, regardless the size or volume of the pour. Such measures shall be to the satisfaction of the Engineer and shall be such that maximum surface crack width on hardened concrete measure immediately after the pour does not exceed 0.004 times the nominal cover of the main reinforcement.
The contractor shall allow for and provide approved instrumentation for the measurement of internal temperature changes in large pours. The maximum concrete temperature at the point of delivery shall not in general exceed the lower of either 37 degree C, or 6 degree C above the prevailing shade temperature in accordance with the recommendations of ACI. The limiting internal temperature differential measured across the extreme faces of concrete mass shall not exceed 25 degrees C at any time.
Curing of hardened concrete shall be executed in accordance with the curing specification. Generally, the element surface shall not be cooled to dissipate heat from the concrete. Curing methods, such as the wetting of heated concrete elements exposed to prolonged and direct radiation, which induce temperature gradients within the concrete mass are strictly prohibited.
For large pours, the contractor shall allow for and take extra precautions to reduce concrete temperature gradient and to prevent the loss of surface moisture. Such measures include but are not limited to:
•Keeping all mix constituents shaded where possible to reduce their temperatures in the stockpile
•Cooling of mixing water and/or replacing part or whole of the added water with ice.
•Reducing the cement content by the use of admixtures (but not below that required for the durability)
•Using a cement with a lower heat of hydration
•Injecting liquid nitrogen after mixing of concrete
•Restring the time between mixing and placing of the concrete to not more than 2 hours
•Providing approved surface insulation continuously over all exposed surfaces to prevent draughts and to maintain uniform temperature through the concrete mass
•Initiating curing immediately after final tamping and continue until the approved surface insulation system is fully in place
•Providing shade to the concrete surface to prevent heat gain from direct radiation.
If the surface exhibits crack after compaction, it shall be retamped to close the cracks while the concrete is still in plastic stage.
Roller Compacted Concrete (RCC) is, as it name implies, concrete compacted by roller. It is therefore differs from conventional concrete in its consistence as it must support rollers in its unhardened state.
The RCC concrete mix must be dry enough to prevent the sinking of the roller but wet enough to permit adequate distribution of the binder during mixing and compaction operations. The development of RCC has caused a major shift in the practice of constructing mass concrete dams which can now be finished as much as 1 to 2 years earlier than conventional mass concrete dams. Up tp 18 000 cubic meter of RCC can be placed in one day.
RCC is constructed similarly to layer-works in road construction and using similar equipment. RCC is placed using dump trucks or conveyors, spread by bulldozers or special modified asphalt pavers. Extenders are extensively used in RCC to reduce costs and to control temperature rises during hydration of cement. RCC is proportioned by using both soil compaction principle and basic concrete technology.
The first Roller Compacted Concrete RCC dam built in the USA was the Willow Creek Dam on Willow Creek, a tributary in Oregon of the Columbia River. RCC is also extensively used for concrete pavements, particular in Canada and Spain. Some low-volume roads have been build in South Africa.
Chemical concrete admixtures are material in the form of powder or fluids that are added to concrete to give it certain characteristics not obtainable with plain concrete mixes. In normal use, admixture dosages are less than 5% by mass of cement and are added to the the concrete at the time of batching/mixing. The most common types of concrete admixtures are:
1. Accelerators speed up the hydration (hardening) of the concrete.
2. Retarders slow the hydration (hardening) of the concrete, and are used in large or difficult pours where partial setting before the pour is complete is undesirable.
3. Air-entrainers add and distribute tiny air bubbles in the concrete, which will reduce damage during freeze-thaw cycles thereby increase the concrete’s durability.
4. Plasticizers (water-reducing admixtures) increase the workability of plastic of fresh concrete, allowing it be placed more easily with less consolidating effort.
5. Superplasticizers ( high-range water-reducing admixtures)are a class of plasticizers which have fewer deleterious effects when use to significantly increase workability. Alternatively; plasicizers can be used to reduce the water content of a concrete (and have been called water reducer due to this application) while maintaining workability. This improves its strength and durability characteristics.
6. Pigments can be used to change the color of concrete, for aesthetics. Mainly they are ferrous oxides.
7. Corrosion inhibitors are used to minimize the corrosion of steel and steel bars in concrete.
8. Bonding agent are used to create a bond between old and new concrete.
9. Pumping aids improve pumpability, thicken the paste and reduce dewatering of the paste.
Thus, chemical admixture is one ingredient creating concrete that provide the differentiation of concrete types.
A variety of different organizations are possible for quality and safety control during construction. One common model is to have a group responsible for quality assurance and another group primarily responsible for safety within an organization.
In large organizations, departments dedicated to quality assurance and to safety might assign specific individuals to assume responsibility for these functions on particular projects. For smaller projects, the project manager or an assistant might assume these and other responsibilities. In either case, insuring safe and quality construction is a concern of the project manager in overall charge of the project in addition to the concerns of personnel, cost, time and other management issues.
Inspectors and quality assurance personnel will be involved in a project to represent a variety of different organizations. Each of the parties directly concerned with the project may have their own quality and safety inspectors, including the owner, the engineer/architect, and the various constructor firms. These inspectors may be contractors from specialized quality assurance organizations. In addition to on-site inspections, samples of materials will commonly be tested by specialized laboratories to insure compliance. Inspectors to insure compliance with regulatory requirements will also be involved. Common examples are inspectors for the local government’s building department, for environmental agencies, and for occupational health and safety agencies.
The US Occupational Safety and Health Administration (OSHA) routinely conducts site visits of work places in conjunction with approved state inspection agencies. OSHA inspectors are required by law to issue citations for all standard violations observed. Safety standards prescribe a variety of mechanical safeguards and procedures; for example, ladder safety is covered by over 140 regulations. In cases of extreme non-compliance with standards, OSHA inspectors can stop work on a project. However, only a small fraction of construction sites are visited by OSHA inspectors and most construction site accidents are not caused by violations of existing standards. As a result, safety is largely the responsibility of the managers on site rather than that of public inspectors.
While the multitude of participants involved in the construction process require the services of inspectors, it cannot be emphasized too strongly that inspectors are only a formal check on quality control. Quality control should be a primary objective for all the members of a project team. Managers should take responsibility for maintaining and improving quality control. Employee participation in quality control should be sought and rewarded, including the introduction of new ideas. Most important of all, quality improvement can serve as a catalyst for improved productivity. By suggesting new work methods, by avoiding rework, and by avoiding long term problems, good quality control can pay for itself. Owners should promote good quality control and seek out contractors who maintain such standards.
In addition to the various organizational bodies involved in quality control, issues of quality control arise in virtually all the functional areas of construction activities. For example, insuring accurate and useful information is an important part of maintaining quality performance. Other aspects of quality control include document control (including changes during the construction process), procurement, field inspection and testing, and final checkout of the facility.
Building codes are a set of rules that must be followed to satisfy the minimum acceptable levels of safety for buildings and non-building structures. The objective of building codes is to ensure the health, safety and protection of the public when it comes to the construction and occupancy of buildings. Building codes are determined by appropriate authorities in different areas and may vary widely from country to country.
Many countries have national building codes, developed by government agencies and applied to all building and construction work across the country. Many local jurisdictions have developed their own building codes. In America, New York and Chicago are the only two cities to use their own building codes.
Building codes are usually applied to the engineers and architects designing the building. They also serve as guidelines for safety inspectors. Others who use building codes include manufacturers of building material, insurance companies, real estate developers and tenants.
Building codes stipulate details of the construction and maintenance of a building or construction. These include fire safety rules: safety exits in buildings, limitations regarding how far a fire should spread and the provision of adequate fire fighting equipment. There are also structural rules; buildings need to be strong enough to resist internal and external forces without collapsing. Building codes also cover health stipulations such as adequate air circulation, washrooms and plumbing facilities.
Building codes can makes sure that proper noise limitations are set in place to protect occupants from noise pollution through walls and windows. There may also be special provisions to ensure that disabled people have proper access to and throughout the property. Anyone who builds a construction and fails to adhere to the proper building codes is liable to very severe penalties.
Construction accidents are one of the most common work related personal injuries. Construction injuries may be the result of machinery failure involving fork lifts, cranes, front end loaders and any other piece of construction machinery found on the job site. They may also involve faulty safety equipment, falling debris, lack of proper training for construction workers, improperly assembled scaffolding, structural collapse, electrical fires, electrocution and a slew of other job site violations.
Under the U.S. Department of Labor, The Occupational Safety and Health Administration (OSHA) must protect those who work in the construction industry. OSHA guarantees a certain level of safety for any construction worker who works on high risk job sites and is exposed to hazardous conditions. In addition, the State of Oregon protects construction workers under the Oregon’s Employer Liability Law. This law requires all construction companies engaged in dangerous work to take every necessary precaution in order to prevent worker injury on the job site.
Construction is a dangerous profession and there are many hazards in the construction workplace. While these state and federal regulations are necessary, they offer only a small amount of comfort to construction workers and their families. In many cases, construction workers are victims of irresponsible employers and are exposed to unnecessary risk while at work. It is also common for third party members, such as contractors and subcontractors, to be present on the job site, creating hazardous and chaotic conditions for the workers.
No matter what construction company you work for, it is the responsibility of the construction company to educate their workers on proper safety precautions and to make sure the job site meets all safety regulations. The Department of Labor and Industries examined construction injuries over a four year period. They found the following seven injuries to be the most common (they also accounted for 92 percent of all compensable claims):
• Work-related musculoskeletal disorders of the neck, back and upper extremities
• Workers struck by heavy machinery or falling objects
• Workers pinned up against a wall by machinery or motor vehicles
• Workers caught inside or underneath a piece of machinery
• Slips or falls on ground level of the construction site
• Falls from an elevated height of the construction site
• General motor vehicle injuries
If you or someone you know has been injured on a construction site, contact a personal injury lawyer to help you with your case. An experienced personal injury attorney will know how to deal with multiple insurance policies, identify all parties involved in the construction process and help you figure out who is responsible for the construction injury.
What is a garage
Garages are used to park cars. This can be a private lot at an airport or a mall, or a storage shed with a garage door at a private home. A car garage can be used strictly for model cars at wealthy homes, or it can be a place for car repair at a car shop. With or without car covers, a garage is always a place for storage, and usually for cars and other vehicles. In the next paragraph, we will talk about how to build a garage for your private house.
Garage Building Guide
Here are four steps for building a garage:
•find a suitable location,
•lay the foundation,
•frame the garage,
•install the roof.
A garage is an unheated space that is used to store a car or other equipment. Garages are usually located fairly close to a primary residence, for the convenience of the homeowner. Using a garage increases the life of a vehicle and can be used to store equipment and supplies securely.
The first step before you even start to build a garage is to obtain permission. If you live in an urban area, there are specific zoning rules and regulations that must be met in order to build a garage. Complete the required forms and make sure that all the legal requirements are met before you begin. The government can tear down an illegally built garage, costing you time and money. In a rural setting, there are fewer restrictions, especially if the land is yours.
The most suitable location for a garage has a straight path to a road or driveway, is close to the primary residence, and does not require the removal of any trees or large shrubs. Take the time to determine the location of any gas, electrical, water, or sewer lines on your property. This information is very important. Although the foundation does not require deep drilling, if the garage is built over any pipes or cables and there is a problem, it may be necessary to dig up the floor.
To lay the foundation, rent a bulldozer and survey equipment. Measure the space required and dig down to create a level surface with the required dimensions to create a foundation when you build a garage. Use the survey equipment to ensure that it is as close to level as possible. Install boards around the perimeter and base, creating a box to hold the concrete. Lay down a layer of gravel and then arrange for the concrete to be poured.
Framing the garage requires the use of wood or prefabricated walls to create the structure. Most people use a team at this stage, as the work moves faster with more people helping. Make a large mark on the floor to indicate where the garage door(s) will be. This will ensure that they are not accidentally closed in.
Footings are structural members used to support columns and walls and to transmit and distribute their loads to the soil in such a way that the load bearing capacity of the soil is not exceeded, excessive settlement, differential settlement,or rotation are prevented and adequate safety against overturning or sliding is maintained.
Types of Foundation
1- Shallows Foundations
Shallow foundations are those founded near to the finished ground surface; generally where the founding depth (Df) is less than the width of the footing and less than 3m. These are not strict rules, but merely guidelines: basically, if surface loading or other surface conditions will affect the bearing capacity of a foundation it is 'shallow'
Shallows foundations are used when surface soils are sufficiently strong and stiff to support the imposed loads; they are generally unsuitable in weak or highly compressible soils, such as poorly-compacted fill, peat, recent lacustrine and alluvial deposits, etc.
Shallow Foundation Types
1. Pad or column footings ( Isolated or Combined )
used to support single columns. This is one of the most economical types of footings and is used when columns are spaced at relatively long distances
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usually support two columns, or three columns not in a row. Combined footings are used when tow columns are so close that single footings cannot be used or when one column is located at or near a property
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2. Cantilever or strap footings
consist of two single footings connected with a beam or a strap and support two single columns. This type replaces a combined footing and is more economical.
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3. Continuous footings
support a row of three or more columns. They have limited width and continue under all columns.
Bay Bridge Public Information Office
Stressed public budgets and delayed passage of long-term federal funding have taken a toll on many transportation infrastructure projects in the United States during the last year. Nevertheless, many significant projects are moving ahead. The inaugural CE News Transportation Projects Roadmap lists 50 notable transportation infrastructure projects in the United States — ranked by estimated cost — that are currently in some stage of planning, design, or early construction. The list includes 21 road/highway/bridge projects, 17 rail/transit projects, seven port/waterway projects, and five airport projects.
While some of these projects have existed in some form of discussion or planning for almost a decade — see the Alaskan Way Viaduct — most are in initial phases of design or construction, with estimated completion dates as far off as 2024. Of course, given uncertain funding, prolonged right-of-way acquisition battles, and public or interest-group opposition, completion dates are likely to slip for some projects. Some projects may remain in initial planning stages for another decade or longer; some may never be built.
But other projects may end up on a fast track, influenced by outside factors. For example, widening of the Panama Canal, currently in progress, will allow larger container ships to pass through and reach East Coast and Gulf Coast ports. However, many of those ports cannot currently handle the larger ships, so not only do the ports need upgrading, but also the rail lines and roads serving those ports.
High-speed rail appears to be on a fast track in California and Florida. San Francisco broke ground in August on the nation’s first high-speed rail station (see page 8), even though construction on the California High-Speed Rail project is at least two years away. Public and private interest in high-speed rail is at an all-time high in the United States, but will that interest sustain and translate into adequate funding?
Fortunately, public coffers will not be the sole source of support. A significant number of the projects listed on the following pages are relying on some form of public-private partnership (P3) to move ahead.
Because of the number of uncertainties inherent in large construction projects, the CE NewsTransportation Projects Roadmap is a dynamic resource. Some projects will drop from the list as they are completed or become casualties of insufficient funding or public opposition; many more (hopefully) will be added. Please help us improve the accuracy and value of this list by submitting information, photos, and website links of large projects — estimated costs of $100 million or more — to firstname.lastname@example.org.
North American Strategic Infrastructure Leadership Forum
CG/LA Infrastructure, LLC will hold its second annual North American Strategic Infrastructure Leadership Forum, Sept. 29-Oct. 1, 2010, in Washington, D.C. The conference offers brief presentations of the top transportation, water, wastewater, and energy infrastructure projects in North America, as well as workshops, roundtables, and networking opportunities. Conference and registration information is available at www.cg-la.com/nalf2 Also check out CG/LA’s Top 100 Infrastructure Projects in North America.
North American Strategic Infrastructure Leadership Forum
CG/LA Infrastructure, LLC will hold its second annual North American Strategic Infrastructure Leadership Forum, Sept. 29-Oct. 1, 2010, in Washington, D.C. The conference offers brief presentations of the top transportation, water, wastewater, and energy infrastructure projects in North America, as well as workshops, roundtables, and networking opportunities. Conference and registration information is available atwww.cg-la.com/nalf2 Also check out CG/LA's Top 100 Infrastructure Projects in North America.
Click here to view "Road-Highway-Bridge"
Click here to view "Rail-Transit"
Click here to view "Port-Waterway"
Click here to view "Airport"
Bridge design books
Bridge Detailing Manual
Bridge Engineering Substructure Design By Wai Fa Chen
Guidelines Bridge Design
Theory and Design of Bridges by Petros P Xanthakos
MODERN PRESTRESSED BRIDGES
Bridge Engineering Seismic Design by Wai Fah Chen & Lian Duan.
Bridge Deck Behaviour By E C Hambly (Second Eddition)
Bridge Design Aids - April 2005
Structural analysis books
Modern experimental stress analysis- J.F.Doyle
Passive Energy Dissipation Systems in Structural Engineering
Practical Yield line Theory By Gerard Kennedy
Space grid by John Chilton
Structural Analysis By IIT Madras
Structural Analysis by IIT Kharangpur
Examples in Structural Analysis by William M. C. Mckenzie
Crack Analysis in Structural Concrete Theory and Applications by Zihal Sai
The Structural Engineers Professional Training Manual
Theories and Applications of Plate Analysis by Rudolph Szilard
Vibration of thick cylindrical structures by Humid Hamidzadeh
Structural and Stress Analysis by Megson, T.H.G
Theory of Plates and Shell By Timoshenko (Second eddition)
Structural Analysis, 7th Edition by R.C. Hibbeler
Diverting parts of the Mississippi would create up to 1000 square kilometres of new wetlands between New Orleans, Louisiana and the Gulf of Mexico, forming a vital storm surge buffer against hurricanes, researchers say. The formation of new delta lands could also help stem ongoing coastal erosion without disrupting important shipping traffic.
"The scientific and engineering barriers are easily overcome," says Gary Parker, a geologist and engineer at the University of Illinois in Urbana-Champaign, who developed the plan with colleagues. "The big issue is political will".
Details of the scheme were unveiled on Sunday at the annual meeting of the American Association for the Advancement of Science in Boston, US.
Breaching the levee
The proposed diversion would cut breaches into a levee some 150 km south of New Orleans, Louisiana, and 30 km above where the river empties into the Gulf of Mexico. With the diversions in place, flooding would cause the river to empty into shallow saltwater bays on either side of the river, releasing sediment-rich water to produce new deltas.
"You keep the sediment within the coastal boundary current that keeps it running along the shoreline, whereas now it gets ejected into the Gulf," adds Robert Twilley, of Louisiana State University in Baton Rouge, who worked with Parker on the project.
A similar plan, presented to the state of Louisiana and the Army Corps of Engineers in 2005, before Hurricane Katrina flooded much of New Orleans, never gained political support. "It was too bold, too aggressive, and too expensive," Twilley says.
But researchers have since worked out how to model the effect of diversions in greater detail, providing better evidence that such an ambitious plan would be successful. Parker and Twilley used a model featuring a detailed picture of the amount of sediment coming down river, the volume of floodwater and the topography of the areas the sediment would fill.
Assumptions about the amount of new delta land that would appear were based partly on an analysis of the nearby Wax Lake Delta, which began forming in 1974 after flooding.
The team ran simulations factoring in varying rates of soil subsidence (1 millimetre to 10 mm) and rising sea level (2 mm to 4 mm per year). Depending on these variables, they estimate that between 700 and 1000 square km of new land would form over 100 years. Land is already being lost to coastal erosion in the state two to three times as quickly.
Twilley says the new delta land would provide significant storm surge protection – more than can be achieved through levies alone – for New Orleans.
Shipping not affected
But a major stumbling block for any plan to alter the Mississippi's flow is the potential disruption caused to shipping between the Gulf and New Orleans – one of the world's busiest ports. The proposed diversion would mainly take water during times of flood, leaving the river's shipping lanes untouched when they are needed most.
"This is achievable even given that navigation is the number one priority," Twilley says. The researchers plan to present their findings to members of Louisiana's state legislature in the coming weeks.
"The state has to say this is what we want to move forward and I feel confident they will do that," Twilley adds. "This is not cheap, but we have done bigger engineering projects in this country before."
Geothermal energy generation is not just limited to ground source heat pumps, construction is set to begin on the UK’s first commercial scale power station in October. Gemma Goldfingle finds out how large scale geothermal energy can be generated.
After four years in development, a 60MW geothermal power plant is finally set to get underway in Redruth, Cornwall. A planning application was submitted in March following months of consultation with local residents. Geothermal Engineering, the company behind the groundbreaking scheme is confident it will be approved.
“We have been working with the local authority for a long time and they are very keen for this sort of development to be located in the area. Residents have also been overwhelmingly positive about the scheme”, says Geothermal Engineering managing director Ryan Law.
“The area is remote so no disturbance will be caused during drilling. As the scheme is under the ground, there is no effect on aesthetics either. Plus at the end of it, residents will benefit from very low cost heating”.
While shallow drilling for geothermal energy can help heat and cool a building, deep geothermal heat and cool an entire community. The scheme works much on the same principle as shallow drilling but at much greater depths. Wells are drilled down to over 4km in depth into granite where temperatures exceed 170oC.
Water is pumped down into the rock, where it will be naturally heated, before being pumped back to the surface as hot water or steam. Heated water will be used to power turbines to generate electricity and as a renewable heat source for the local area.
Initially three wells will be drilled at Redruth. From these three wells, over 10MW of electricity will be generated, enough to power 15,000-20,000 houses, and over 50MW of thermal energy, which can power 20 hospitals. This thermal energy will be connected to a district heating system and will provide “very low cost heating” for the local area around Redruth.
“Heat is essentially a waste product for us. We are harnessing the electricity from the scheme and connecting into the grid. However, this bi-product can power an entire community”, says Law.
Deep drilling for geothermal is not new. From 1976 to 1991 the Hot Dry Rock research project was carried out in Cornwall, where water was pumped down a 2.5km well. The aim of the government funded project was to understand rock mechanics at such depths rather than generate power.
In 1991, the project moved to Soultz on the France-Germany border where it remains today, and the UK’s foray into geothermal energy came to a swift halt.
“Since the Hot Dry Rock project there has been a hiatus in the UK. In the meantime, geothermal has grown into a booming industry in many other countries including Germany, Australia and the US”, says Geothermal Engineering managing director Ryan Law.
Law cites “The Future of Geothermal Energy” report published by MIT in 2006 as a big turning point for the industry. “The world started to take notice”, he says. The report confirmed that deep geothermal could be a key energy source in the US. This started a global “heat rush”, and encouraged major investment in deep drilling schemes from both private and public investors.
At this point Law was a geotechnical engineer at consultant Arup who had worked on several shallow to medium geothermal schemes. He saw a real possibility in making large scale geothermal schemes a reality in the UK. The consultant agreed to undertake research into the technical feasibility of a scheme.
“The Hot Dry Rock project gave us lots of data so we didn’t have to carry out any drilling. We took the data apart to choose the site and the geological concept for the scheme.”
"We have an unlimited energy resource under our feet. If we can make it economically viable to drill down 6km, the whole of the Uk can be opened up." Ryan Law
In 2008, Law set up Geothermal Engineering, a company dedicated entirely to getting this project off the ground, although Arup remains a close partner on the scheme. Law brought in the greatest geothermal expertise in the UK to work on the plant, including Dr Tony Batchelor who led the original Hot Rocks Project.
To make geothermal energy commercially viable, hot granite rock needs to be found relatively close to the surface. Deep drilling is so expensive, the return on investment will be diminished if depths exceed 5km. The UK’s geology limits development to Cornwall and Devon where hot granite is found at depths of 4km.
Redruth in Cornwall is the chosen site. Firstly, the patch of land is remote so there are no neighbours to disturb during the immense drilling operation. Secondly, a fault line runs vertically through the site.
“We didn’t want to replicate the Hot Rock Project. The principle of harnessing geothermal energy centres on drawing heated water back to the surface. On the HRP, that didn’t happen at first. A further well had to be drilled to draw up the water. We can’t afford for this not to work the first time. Best practice from the Continent shows that drawback occurs when the water passes through the earth’s natural faults”, says Law.
Drilling begins in October this year on the first well. A 50m high rig will drill continuously, 24 hours a day, for four months to create the 4.5km deep well which will intersect with the natural fault. These rigs are designed for the oil and gas industry and have an enormous 350MT pulling power.
Water will then be pumped into the 914mm hole which narrows to 203mm at the base. At this point, unlike the Hot Dry Rock project, testing will be carried out to find out how water travels through the hot rock.
Geothermal Engineering is working with Durham University and the British Geological Society to monitor the waters journey through the fractures in the granite. Some 15 seisometers will be used at surface level to pick up seismic movements and generate a 3D view mapping how the reservoir has developed.
This allows certainty in the location of the two further wells which will draw the heated water back out. At surface level the wells will only be 5m apart. The drill will be angled to hit the water channel created which could travel as far as 1km from the original well.
The three wells will generate more than 10MW of electricity and around 50MW of thermal energy
Deep drilling is not cheap; the three wells at Redruth will cost £40M. The scheme was awarded £1.475M from the first tranche of the Department of Energy and Climate Change’s (DECC) Deep Geothermal Challenge Fund. A total of £6M is up for grabs for geothermal projects across the UK.
Law is hoping Redruth will benefit further from the government fund when the next tranche of awards is announced. Both European Commission and regional development agency funding is also being sought, although private investment is set to bankroll the bulk of the scheme.
“Government financing is languishing behind other countries. Obama has pledged $330M into deep geothermal and the Australian Government match private investment funding to kickstart the industry”, says Law.
Geothermal Engineering is currently in talks with many potential investors, including large oil and gas companies, renewables firms and private equity companies. He remains confident that the finance will be secured.
“We will be drilling in October”, Law emphasises. “The rig has been ordered, it’s happening. Of course geothermal has high start up costs but it produces a lot of electricity from just three wells. As well as the 5p per kilowatt-hour (kW/h) from the electricity produced, investors also get 1.5pkW/h from the heat produced following the introduction of the Renewable Heat Incentive”.
The geothermal plant takes relatively little time to set up. Despite the extra testing needed on this start-up project, Redruth will be operational by 2013, before both the first new nuclear power plant and any Round Three offshore wind farms.
If the three wells prove successful, the plan is to produce over 30 more plants across Devon and Cornwall.
“We have an unlimited energy resource under our feet, ready to be harnessed. If we can make it economically viable to drill down to 6km, as MIT say we can, then the whole of the UK can be opened up”, says Law.
Researchers from North Carolina State University have developed a sensor that allows engineers to assess the scour potential of soils at various depths and on-site for the first time – a technology that will help evaluate the safety of civil infrastructure before and after storm events. Scour, or erosion of soil around structures due to water flow, is responsible for a wide range of critical infrastructure failures – from unstable bridges to the levees that gave way in the wake of Hurricane Katrina.
The ISEP will help authorities prepare for, or minimize the impact of, events such as the failure of the levees in the wake of Katrina.
“The ‘in situ scour evaluation probe’ (ISEP) is the first technology that allows technicians in the field to measure the scour potential of soils without the need for excavation,” says Dr. Mo Gabr, a professor of civil, construction and environmental engineering at NC State and co-author of a paper describing the new device. “Previous technologies required engineers to take samples and process them in a lab.”
Understanding scour potential is important because it can help authorities prepare for, or minimize the impact of, events such as the failure of the levees in the wake of Katrina. Scour has also been linked to approximately 60 percent of the bridge failures in the United States, as documented by the Federal Highway Administration.
“The ISEP’s ability to measure scour potential at different depths helps us predict how the soil will behave in the future as a support media, as various layers of soil are eroded or scoured,” Gabr says.
The ISEP will also allow end-users such as federal and state agencies and private consultants to perform scour assessment more frequently, since they will not have to take physical samples back to a lab for analysis. More testing data means researchers will have a larger data set to work with, which should help them to more accurately predict scouring rates and behavior.
The new probe uses a water jet to burrow a hole into the soil. Researchers can track the rate at which the water displaces the soil to determine the scour rate. Researchers can also manipulate the velocity and flow rate of the water to simulate various natural events – from normal stream flow to hurricane-induced surges.
The researchers plan to take the ISEP to North Carolina’s Outer Banks later this month to help with research efforts related to dune erosion.
The paper, “In Situ measurement of the scour potential of non-cohesive sediments (ISEP),” was presented Nov. 8 at the 5th International Conference on Scour and Erosion in San Francisco, Calif. The lead author is NC State graduate student Cary Caruso. The ISEP was developed under a grant from the U.S. Department of Homeland Security (DHS), as part of the work being done by the DHS Center of Excellence on Natural Disasters, Coastal Infrastructure and Emergency Management.
Note to Editors: The study abstract follows.
“In Situ measurement of the scour potential of non-cohesive sediments (ISEP)”
Authors: Cary Caruso, Mohammed Gabr, North Carolina State University
Presented: Nov. 8, 5th International Conference on Scour and Erosion in San Francisco, Calif.
Abstract: A vertical probe (VP) employing a water jet has been developed for assessing scour potential and erosion rates of sediments typically found at the bottom of rivers or streams. The probe for “In Situ measurement of the scour potential of non-cohesive sediments (ISEP)” is based on the idea that analysis of the probe penetration rate into the soil correlates with scour rate and erosion potential. The method proposed herein aims at measuring the potential scour rate in situ and as a function of depth. Results on test sands (mean particle diameter (D50 ~0.3mm) suggest that the rate of advancement of the probe is proportional to the vertical velocity of the water at the tip of the probe raised to a positive exponent. For the saturated sand used in testing, the exponent appears to be 1.4. The rate of embedment varies with moisture content. Thus far, scour rates determined with this proposed method are found to be in reasonable agreement with scour rates published for similar sands.
Sunday, December 5, 2010
8 mm 6,48
10 mm 8,10
12 mm 9,72
14 mm 11,34
16 mm 12,96
18 mm 14,58
1 1/2" 5,00
Siyah Dişli Manşonlu
Hazır Sıva (KDV Hariç) (TL/KG)
Sıva ve Duvar Örme Harcı 75,000
Gazbeton Yapıştırma Harcı 190,000
Çimento Bazlı Makina Sıvası 138,450
Alçı Bazlı Makina Sıvası 145,800
Beton B25 86,250
Püskürtme Beton 85,000
Kendiliğinden Yerleşen Beton 162,500
Ankraj Harcı 540,000
beton Tamiri Harcı 282,000
İnşaat demir fiyatlari 16 Mart 2010 itibari ile nervürlü 12-14-16 lik demirin tonu 890 TL oldu+ (KDV %18 + Nakliye)
Nervürlü 12-14-16 mm ve 18-20-22 mm inşaat demirinin fiyatinda, geçen sürede küçük çapli degisiklikler oldu. Gelinen noktada, 16 Mart itibariyle KARDEMIR`de 12-14-16 mm ve 18-20-22 mm nervürlü insaat demiri ton fiyati ( TL/Ton):890 TL+ KDV(% 18)+Nakliye(ton basina ortalama 20 ile 60 TL arasi uzakliga göre degisir)
890 TL oldu.( 16 Mart 2010 ) (KDV+ Nakliye hariç)
865 TL idi.( 10 Mart 2010 ) (KDV+ Nakliye hariç)
830 TL idi.( 8 Mart 2010 ) (KDV+ Nakliye hariç)
788 TL idi.( 1 Mart 2010 ) (KDV+ Nakliye hariç)
755 TL idi.( 25 Şubat 2010) (KDV+ Nakliye hariç)
793 TL idi.( 16 Ocak 2010 ) (KDV+ Nakliye hariç)
776 TL idi.( 14 Ocak 2010 ) (KDV+ Nakliye hariç)
746 TL idi. ( 28 Aralik 2009 ) (KDV+ Nakliye hariç)
721 TL idi. ( 4 Aralik 2009 ) (KDV+ Nakliye hariç)
712 TL idi. ( 17 Kasim 2009 ) (KDV+ Nakliye hariç)
685 TL idi. ( 7 Kasim 2009 ) (KDV+ Nakliye hariç)
657 TL idi. ( 25 Ekim 2009 ) (KDV+ Nakliye hariç)
720 TL idi. ( 2 Ekim 2009 ) (KDV+ Nakliye hariç)
708 TL idi. ( 28 Eylül 2009 ) (KDV+ Nakliye hariç)
729 TL idi. ( 7 Eylül 2009 ) (KDV+ Nakliye hariç)
745 TL idi. (18 Agustos 2009) (KDV+ Nakliye hariç)
716 TL idi. (31 Temmuz 2009) (KDV+ Nakliye hariç)
1300 TL idi. ( Ekim 2008 )(KDV+Nakliye dahil )
2100 TL idi. ( Mayis 2008)(KDV+Nakliye dahil ) En yüksek fiyat
Hazır Beton ve Çimento Fiyatları - 2010
Hazır Beton ve Çimento Fiyatları -2009-2020 yılı güncel fiyat listesi
2010 Güncel Çimento Fiyatları
Çimsa Beyaz Çimento (50kg) - 14 TL/Torba (Kdv Dahil) - Öztürkler Çimento
Portlan Çimentosu (1 ton) - 129 TL/Ton (Kdv Hariç) - Nuh Çimento
Puzolanik Çimento (1 ton) - 122 TL/Ton (Kdv Hariç) - Nuh Çimento
2010 Güncel Hazır Beton Fiyatları
Hazır Beton C25 (Pompalama Dahil) 75 TL/M3 (Kdv Hariç) - Set Beton
Hazır Beton C30 (Pompalama Dahil) 80 TL/M3 (Kdv Hariç) - Set Beton
Hazır Beton C25 (Pompalama Dahil) 103 TL/M3 (Kdv Hariç) - Nuh Beton
Hazır Beton C30 (Pompalama Dahil) 109 TL/M3 (Kdv Hariç) - Nuh Beton
Alkent 2000'in üçüncü bölümüne yapılacak Göl Malikaneleri 63 villadan oluşuyor. 5 dönümlük bahçe içinde müstakil yüzme havuzlu olan villaların büyüklükleri 1200 metrekareye ulaşıyor
Büyük tip villalarda 8 yatak odası, 150 metrekarelik salon, aynı çatı altında ayrı bir ev gibi tasarlanan misafir suiti, sinema odası, dört araçlık kapalı otopark yer alıyor. Villaların fiyatları 750 bin dolar ile 1 milyon 790 bin dolar arasında değişiyor
Büyükçekmece gölü kıyısında yer alan Alkent 2000'in üçüncü bölümünü oluşturacak 'Göl Malikaneleri'nin satışı başladı. Alkent 2000'in Büyükçekmece gölüne doğru uzanmasını sağlayacak 63 villa, göl manzarasının yanı sıra içinde yüzme havuz bulunan 5 bin metrekareye varan bahçelere de sahip olacak. Villaların 1200 metrekareye ulaşan büyüklükleri de malikane adının hakkını veriyor. Villaların fiyatları 750 bin dolar ile 1 milyon 790 bin dolar arasında değişiyor.
Alarko Arazi Geliştirme Grubu Koordinatör Yardımcısı Kadir Eke, villaları peşin satacaklarını, ancak dört banka ile anlaştıklarını, buna göre bankalara bedelin yüzde 25'inin peşin, kalanın da 240 aya varan vadede ödenebileceğini anlatıyor.
Sinema odası da var
24 ayda bitirilip teslim edilecek Göl Malikaneleri'nin Tapma, Magnifico, Laguna, Adella, Dalia, Grandezza ve Palazzio adını taşıyan yedi farklı tipte olacağını belirten Eke şunları söylüyor:
"Emsallerini ancak Florida'da görebileceğiniz Palazzio, Grandezza ve Dalia tiplerinde 150 metrekareye varan salon, sekiz yatak odası, çalışma odası, oturma odası, sinema odası, ek salon, yatak odası ve mutfaktan oluşan misafir suiti, ayrıca yardımcı odası ile dört araçlık kapalı otopark mevcut."
Cennetten geçen yol
Göl Malikaneleri'nin mimari ve peyzaj projelerinin Floridalı usta mimarlara hazırlatıldığını kaydeden Kadir Eke, şu bilgileri veriyor:
"Alkent 2000'in girişinde yer alan hurma ve palmiyelerle donatılmış egzotik peyzaj, fıskiyeli havuzlar, aslan heykelleri ve şelaleler Göl Malikaneleri'nin de girişinde gelenleri karşılayacak. Üçüncü fazda yaşayacak olanlar mutlaka bu cennetin ortasından geçerek malikanelerine gidecek."
Alkent 2000'in üçüncü fazında yeni bir uygulamaya da başladıklarını anlatan Kadir Eke, "Göl Malikaneleri, dekorasyona hazır. Yani evin dış görünüşünü beğenip aldıysanız, iç mekanlarda tamamen özgürsünüz. Kendi yaşam tarzınızı yansıtacak yerleşim planı yapabiliyorsunuz" diyor.
Projenin bir diğer özelliğinin de merkezi jeneratör sistemi olduğunu ve böylece elektrik kesintilerinin hiç hissedilmeyeceğini belirten Eke, projenin yapımına ilişkin de şu bilgileri veriyor:
"Projemizde yer alan villalarımızın tümü radye general temel üzerine betonarme karkas olarak inşa edilecek. Villa betonarmeleri ileri kalıp teknolojileriyle brütbeton olarak yapılacak. Kullanılacak betonun 1 santimetrekaresi 300 kilogram yük taşıma kapasitesinde olacak. Yapılarımızda su-ısı yalıtımı için gerekli önlemler alınacak ve yapılar dış etkenlere karşı korunacak."
İşadamlarına hitap edecek
Kadir Eke, en üst gelir grubundaki işadamlarına yönelik tasarladıkları malikanelerin ortasında rekreasyon tesislerinin olacağını kaydediyor. Alkent 2000'in çevresinde anaokulundan üniversiteye kadar çok sayıda okulun, alışveriş merkezinden, sağlık merkezine kadar tüm ihtiyaçlara yanıt verecek tesislerin bulunduğunu hatırlatan Eke, şöyle konuşuyor:
"Alkent 2000'in içinde de Türkiye?nin ilk doğa sporları kulübü Wattabe bulunuyor. Burası, dünyada gerek kişisel, gerekse kurumsal olarak yaşam kalitesini artırmanın önde gelen unsurlarından biri olan doğa sporları kavramının Türkiye'deki ilk kurumsal merkezi. Bu merkezde keyifle ATV, 4x4 experience, sea kayak, kano, katamaran, yelkenli, sörf, mountain bike, paintball faaliyetleri bulunuyor. Bir de doğayla iç içe restoran yer alıyor."
Dumankaya İnşaat, iş hayatının hareketlenmeye başladığı Kurtköy'de 376 dairelik home office projesini hayata geçiriyor. Şirket, ilçede kuracağı proje ile doğal kaynakları koruyan, enerji tüketiminde maksimum tasarruf sağlayan ekolojik bir iş ve yaşam merkezi kurmayı vaad ediyor.
Dumankaya Yönetim Kurulu Üyeleri Ali Dumankaya ve Uğur Dumankaya, söz konusu projeyi bölgedeki ticari hareketlilik göz önüne alınarak home office konseptinde geliştirildiğini kaydetti. Uğur Dumankaya, 'Kurtköy bölgesi Sabiha Gökçen Havalimanı, Formula 1 pisti, beş yıldızlı oteller, alışveriş merkezleri, eğitim kampüsleri ve sağlık kuruluşlarıyla birlikte İstanbul'un en hızlı gelişen ticari merkezlerinden birisi oluyor. Bölgedeki bu ticari hareketliliği düşünerek 376 home office'den oluşan Dumankaya Flex Kurtköy'ü geliştirdik. Dumankaya Flex Kurtköy sunduğu sosyal imkanlar ve yüksek teknolojilerle ev ve iş hayatının standartlarını kökten değiştirecek nitelikte bir proje.' dedi.
Ali Dumankaya ise bu projenin iş ile ev yaşamını bir araya getiren home office konseptinin dışında farklı birçok niteliğe de sahip olduğunu belirterek, şöyle konuştu:
'Flex akıllı ev teknolojisinin çevreye duyarlı bir anlayışla harmanlandığı özel bir proje. Leed sertifikasına aday olan Dumankaya Flex Kurtköy doğal kaynakları koruyan, enerji tüketiminde maksimum tasarruf sağlayan ekolojik bir iş ve yaşam merkezi olarak önemli bir yatırım fırsatı sunuyor. Akıllı ev teknolojisi ve çevre duyarlılığı özelliklerinin dışında Flex'te yeni bir hizmet anlayışını daha hayata geçireceğiz. Dumankaya Pusula çerçevesinde Pusula Business adını verdiğimiz bu yeni hizmetler paketi home office kullanıcılarına çok önemli avantajlar sağlayacak.'
Mimari özellikleriyle ilgi çekici bir tasarımı olan Dumankaya Flex Kurtköy'te 5 ayrı blokta toplam 376 adet home office bulunuyor. 40-66 metrekare arası stüdyo home office'ler, 60-86 metrekare arası 1+1 home office'ler ve 90-154 metrekare arası 2+1 home office'ler projedeki daire tiplerini oluşturuyor. Kapalı devre iletişim platformu ile hava durumundan trafiğe, site içi duyurulardan Dumankaya haberlerine kadar her türlü konuda bilgi edinilebiliyor. Pusula Business hizmetleriyle de 7/24 sekreterya destekli concierge hizmetinden firmalara özel Türkçe ve İngilizce 7/24 call center hizmetine, firma çalışanlarının motivasyonuna yönelik özel hobi organizasyonlarından, özel davet ve toplantı organizasyonlarına, her türlü teslimat ve kurye hizmetlerinden hatırlatma servislerine indirimli araç kiralama ve havaalanı transferlerine kadar pek çok hizmetten faydalanmak mümkün.
Saturday, December 4, 2010
Either the wet-mix process or the dry-mix process may be used to produce shotcrete.
Dry mix process
Batching and Mixing
Aggregate and cementitious materials shall be batched by mass. Equipment for batching by mass shall be capable of the accuracy specified in ASTM C94. The mixing equipment shall be capable of thoroughly mixing materials in sufficient quantity to maintain placing continuity and be capable of discharging all mixed material without any carryover from one batch to the next.
The equipment shall be capable of discharge the aggregate-cement mixture into the delivery hose and delivering a continuous smooth stream of uniformly mixed material to the discharge nozzle. The discharge nozzle shall be equipped with a manually operated water injection system (water ring) for directing an even distribution of water through the aggregate-cement mixture. The water valve shall be capable of ready adjustment to vary the quantity of water and shall be convenient to the nozzleman. The water pressure at the discharge nozzle shall be sufficiently greater than the operation air pressure to ensure that the water is completely mixed with the other materials. If the line water is inadequate, a water pump shall be introduced into the line. The water pressure shall be steady (non-pulsating). The delivery equipment shall be thoroughly cleaned at the end of each shift. Equipment parts, especially the nozzle liner and water ring shall be regularly inspected and replaced as required.
Wet mix process
Batching and mixing
Batching and mixing shall be accomplished in accordance with the applicable provisions of ASTM C94. The mixing equipment shall be capable of thoroughly mixing the specified materials in sufficient quantity to maintain continouous placing. Ready-mix shotcrete complying with ASTM C94 may be used.
The equipment shall be capable of delivering the premixed materials accurately, uniformly and continuously through the delivery hose. Recommendations of the equipment manufacturer shall be followed on the type and size of nozzle to be used and on cleaning, inspection, and maintenance of the equipment.
Scope of work:
Injection of dead cracks with low viscosity 2 components epoxy resin in order to repair the concrete structures.
PREPARATION FOR INJECTION WORK
14mm holes must be drilled along the crack path between 200 – 300 mm centres. The holes must be deep enough to receive the ‘metal pipe sleeves’ (approx. 20mm)
Insert Sika ‘metal pipe sleeves’ into all the holes and epoxy into position using Sikadur 731
Clean the concrete surface adjacent to the crack with a wire brush or sandpaper.
Wipe down the concrete with a clean rag to remove any dust and loosely adhering particles.
The cleaned surface is then sealed using Sikadur 731 applied by a spatula or trowel.
Following the curing of the Sikadur 731 (minimum of 12 hours at 30oC) the epoxy injection can commence.
Starting from one side or the lowest point of the crack a Sika ‘nipple’ is screwed into the first pipe sleeve and Sikadur 752 injected into the crack until the epoxy is seen to ooze from the adjacent pipe sleeve, this pipe sleeve is then sealed with a nipple, continue to inject the current port until refusal (epoxy resin can not be injected more) and then start the injection of the adjacent port and so on. This procedure is continued in the sequence indicated until all have been completed.
Beginning at the first nipple filled, the nipple is removed and checked for incomplete filling. If any of the pipe sleeves are found to be incompletely filled, the injection of Sikadur 752 must recommence from the previous pipe sleeve to the one found incomplete until full and the nipple replaced. This checking process is continued (without interruption) along the crack until all have been checked.
After a curing time of 12 hours the sleeve and nipples are trimmed off with an angle grinder or other suitable equipment.
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Concrete Work in Marine Structure Projects
1. Introduction to light weight concrete
Lightweight concrete is mainly used as back-filling material. When talking about lightweight concrete, we refer to a concrete of which its specific gravity (density) is much more lower than normal concrete.
Basically normal concrete: 2.35 – 2.42 ton/m3 while lightweight concrete 0.80-1.40 t/m3.
Therefore final strength is not issue. Expected final strength would be usually lower 5 MPa at 28 dasy as such concrete contained of lot of air entrained.
The strength would be affected by type of lightweight aggregate to used.
2. Production Principle
Basically there are 2 ways to produce light weight concrete.
a. Cement/ Water/Sand/lightweight aggregate/ chemical additives (admixtures)
b. Cement/ Water/ Sand/ Chemical additives
By lightweight aggregate we can consider polystyrene balls, expanded clay for instance. Chemical additives, we mainly means special air entrained agent such as Sika Lightcrete 1-500VP. This admixture ca entrained safely up to 30% of air entrained into the mix.
As per the use of the special air entrained, usually, the mix is batched for a designed volume the air entrained is measured in order to determine final volume of the concrete batched. Indeed in term of concrete production it is important to know about about which volume we are talking, we are referring to:
For instance: Expected air entrained 30%
Volume of fresh batch 1000 liters -> initial ar development 30% –> final hard volume ~1.3 m3
1. Introduction to marine projects:
Marine structures are those structure built on sea or near it, properly designed to withstand internal, external loads and aggressive environmental exposures both physical and chemical in order to prolong service-life.
Reinforced concrete structures as part of marine structure are exposed to severe physical and chemical exposure such as wave impact, sulphate and chloride exposure. In tropical climates, the combination of above deleterious effects may cause severe defects in concrete structure only in very few years.
In order to delay these detrimental effects, high durability, chloride and sulphate resistant concrete become a necessity in constructing marine structure. The use of silica fume with a high water reducing admixture with retarding effect then become increasingly popular to produce a low permeability concrete and high sulphate resistant concrete.
2. Concrete Work in In Marine Structures
High strength concrete and durable concrete
b) Design Criteria:
• Sulphate and chloride resistance
• Low W/C ratio (splash & atmospheric zone < 0.40, submerged < 0.45) target 0.3 – 0.38 W/C
• High strength
• Abrasion resistance
• Low permeability
• Durability (High Performance Concrete = HPC)
c) Concrete Production:
• Objectives: Produce high strength concrete (HSC) & durable concrete (HPC)
• Targets: Maximization of concrete density
• Actions: Adherence to good construction practices
d) Concrete Mix Design:
• Performance for both fresh & hardened
• Maintenance – free during design life
• Re-orientation in the usual mixture design concepts and techniques
• Proper selection of material
• High cementing materials
• Use SilicaFume
• Use superplasticizer
e) Concrete Curing:
• For HSC and other concrete structures, proper curing is essential. In order to maintain a satisfactory moisture content and temperature in concrete during its early stages so that desired properties may develop. The strength and durability of concrete will be fully developed only if it is cured.
• Failure to prevent such excessive evaporation, frequently causes plastic shrinkage and loss of strength in the material near the concrete surface.
Six Sigma was originally developed as a set of practices designed to improve manufacturing processes and eliminate defects, but its application was subsequently extended to other types of business processes as well. In Six Sigma, a defect is defined as anything that could lead to customer dissatisfaction.
The particulars of the methodology were first formulated by Bill Smith at Motorola in 1986. Six Sigma was heavily inspired by six preceding decades of quality improvement methodologies such as quality control, TQM, and Zero Defects, based on the work of pioneers such as Shewhart, Deming, Juran, Ishikawa, Taguchi and others.
Like its predecessors, Six Sigma asserts that –
Continuous efforts to achieve stable and predictable process results (i.e. reduce process variation) are of vital importance to business success.
Manufacturing and business processes have characteristics that can be measured, analyzed, improved and controlled.
Achieving sustained quality improvement requires commitment from the entire organization, particularly from top-level management.
Features that set Six Sigma apart from previous quality improvement initiatives include –
A clear focus on achieving measurable and quantifiable financial returns from any Six Sigma project.
An increased emphasis on strong and passionate management leadership and support.
A special infrastructure of “Champions,” “Master Black Belts,” “Black Belts,” etc. to lead and implement the Six Sigma approach.
A clear commitment to making decisions on the basis of verifiable data, rather than assumptions and guesswork.
The term “Six Sigma” is derived from a field of statistics known as process capability studies. Originally, it referred to the ability of manufacturing processes to produce a very high proportion of output within specification. Processes that operate with “six sigma quality” over the short term are assumed to produce long-term defect levels below 3.4 defects per million opportunities (DPMO). Six Sigma’s implicit goal is to improve all processes to that level of quality or better.
Six Sigma is a registered service mark and trademark of Motorola, Inc. Motorola has reported over US$17 billion in savings from Six Sigma as of 2006.
Other early adopters of Six Sigma who achieved well-publicized success include Honeywell (previously known as AlliedSignal) and General Electric, where the method was introduced by Jack Welch. By the late 1990s, about two-thirds of the Fortune 500 organizations had begun Six Sigma initiatives with the aim of reducing costs and improving quality.
In recent years, Six Sigma has sometimes been combined with lean manufacturing to yield a methodology named Lean Six Sigma.
Silica fume is not a new product by one company but is a major raw material that has been available over 40 years. Silica fume has become the world standard for chloride corrosion situations and also to improve dramatically the water tightness of concrete structures. Waterproofers are viewed suspiciously by the international research industry because of their side affects on strength and porosity.
Below we highlight the positive effects of silica fume and superplasticizer on pore size of cement paste, and porosity, water permeability and water absoption of concrete.
Silica fume in concrete and concrete porosity
Silica fume has an average particle size of less the one micron (100 times finer than cement). In concrete these fine particles fill the gaps between cement grans and react with free lime released during cement hydration. This produces strong calcium silicate hydrates to replace weak lime and voids found in normal concrete.
The effect on the water penetrability is related to the pores size. It has has been shown that water does not penetrate pores less than 6– Angstroms nominal diameter. Silica fume modifies concrete’s pore structure such that few pores are larger than 600 Angstroms.
Because of the fine pore structure water permeability is reduce by 100 times in laboratory test. In reality on site 20 times is more likely.
The cause of porosity is rarely to be found in the aggregate, it is on the contrary a property of the cement paste.
The porosity can be reduced by:
use of admixtures – superplasticizer
precise grading of the aggregates
filling og all voids with admixture (silicafume) that react with the cement (dense packing)
Dense packing depends theoretically only on the shape and size distribution of the individual particles. A packing of spheres of the sme size has 48% voids with cubic packing and 26% voids with hexagonal packing independently of their size. But the packing density depends strictly on th particle shape alone, broken particles cannot be so well compacted as round ones.
The Silica fume technology is based on the following knowledge:
the use of chosen cements
filling the voids between the cement particles with micro-silica (silica fume)
reduce the water content as far as possible with superplasticizers
use of best grading sand and gravel mix
use of good quality aggregates
supervision of concrete compaction
The addition of silica fume with superplasticizer significantly reduces the total porosity of the cement paste.
Water absorption of concrete – effect of silica fume
In concrete constantly immersed in water the pores will reach supersaturation within a few months. After that time absorption becomes immaterial. A waterproofer with reduce the depth to which water is absorbed into the concrete but more significance is increased porosity. Tests have shown that waterproofers may reduce absorption but increae porosity.
Silica fume reduce absorption of concrete by reducing the pore size. Waterproofers increase pore size (because of interference with cement hydration), however improved mix design and supervision may lead to improvement,
Project Management Professional (abbreviation of PMP) is a credential offered by the Project Management Institute (PMI). The credential is obtained by documenting your work experience in project management, completing 35 hours of project management related training, and scoring at least 61% on a written, multiple choice examination. PMP exams administered on or before June 30, 2009 will be based on “A Guide to the Project Management Body of Knowledge” – or PMBOK, the Third Edition. After June 30, PMP certification exams will be based on “A Guide to the Project Management Body of Knowledge” the Fourth Edition of which was published in December 2008.
The Project Management Framework (based on PMBOK Third Edition) embodies a project life cycle and five major project management process areas (encompassing a total of 44 processes). Mapped to these five process areas (Initiate, Plan, Execute, Monitor and Control, and Close) are nine areas of project management knowledge: Integrated Project Management, Scope Project Management, Time Project Management, Cost Project Management, Quality Project Management, Human Resource Project Management, Communications Project Management, Risk Project Management and Procurement Project Management. The nine knowledge areas share common inputs, tools and techniques and outputs, and make facilitates PMP professionals in developing and practicing specialization in one or more of the areas. For example, a PMP may specialize in Quality Planning, Quality Assurance, and Quality Control – the three processes that make up the Quality Project Management process area.
Government, commercial and other organizations employ PMP certified project managers in an attempt to improve the success rate of software development projects by applying a rigorous, standardized and evolving set of project management principles as contained in PMI’s PMBOK.
The PMP Exam will have 200 questions. 25 of them are “pre-release questions,”. These pre-release questions are not included in your final PMP Exam Mark. Your score will be calculated based on 175 PMP questions. The PMI will evaluate your proficiency level on each project management process from high proficiency to low proficiency.