1 | zeety

October 10th, 2008 at 6:50 am

I will follow up..

2 | diystuff.com

December 30th, 2008 at 8:34 am

I wish the guys the best of luck with the 2008 yearbook I’m sure it’s a great resource

3 | NASHWAN HAMID YAHYA AL-EMAD

February 4th, 2009 at 11:01 am

Mixing Concrete

Cement being mixed with sand and water to form concrete
Thorough mixing is essential for the production of uniform, high quality concrete. Therefore, equipment and methods should be capable of effectively mixing concrete materials containing the largest specified aggregate to produce uniform mixtures of the lowest slump practical for the work. Separate paste mixing has shown that the mixing of cement and water into a paste before combining these materials with aggregates can increase the compressive strength of the resulting concrete. The paste is generally mixed in a high-speed, shear-type mixer at a w/cm (water to cement ratio) of 0.30 to 0.45 by mass. The cement paste premix may include admixtures, e.g. accelerators or retarders, plasticizers, pigments, or fumed silica. The latter is added to fill the gaps between the cement particles. This reduces the particle distance and leads to a higher final compressive strength and a higher water impermeability The premixed paste is then blended with aggregates and any remaining batch water, and final mixing is completed in conventional concrete mixing equipment.
High-Energy Mixed Concrete (HEM concrete) is produced by means of high-speed mixing of cement, water and sand with net specific energy consumption at least 5 kilojoules per kilogram of the mix. It is then added to a plasticizer admixture and mixed after that with aggregates in conventional concrete mixer. This paste can be used itself or foamed (expanded) for lightweight concrete. Sand effectively dissipates energy in this mixing process. HEM concrete fast hardens in ordinary and low temperature conditions, and possesses increased volume of gel, drastically reducing capillarity in solid and porous materials. It is recommended for precast concrete in order to reduce quantity of cement, as well as concrete roof and siding tiles, paving stones and lightweight concrete block production.

Curing

Concrete columns curing while wrapped in plastic
In all but the least critical applications, care needs to be taken to properly cure concrete, and achieve best strength and hardness. This happens after the concrete has been placed. Cement requires a moist, controlled environment to gain strength and harden fully. The cement paste hardens over time, initially setting and becoming rigid though very weak, and gaining in strength in the days and weeks following. In around 3 weeks, over 90% of the final strength is typically reached though it may continue to strengthen for decades.
Hydration and hardening of concrete during the first three days is critical. Abnormally fast drying and shrinkage due to factors such as evaporation from wind during placement may lead to increased tensile stresses at a time when it has not yet gained significant strength, resulting in greater shrinkage cracking. The early strength of the concrete can be increased by keeping it damp for a longer period during the curing process. Minimizing stress prior to curing minimizes cracking. High early-strength concrete is designed to hydrate faster, often by increased use of cement which increases shrinkage and cracking.
During this period concrete needs to be in conditions with a controlled temperature and humid atmosphere, in practice this is achieved by spraying or ponging the concrete surface with water, thereby protecting concrete mass from ill effects of ambient conditions. The pictures to the right show two of many ways to achieve this, ponding – submerging setting concrete in water, and wrapping in plastic to contain the water in the mix.
Properly curing concrete leads to increased strength and lower permeability, and avoids cracking where the surface dries out prematurely. Care must also be taken to avoid freezing, or overheating due to the exothermic setting of cement (the Hoover Dam used pipes carrying coolant during setting to avoid damaging overheating). Improper curing can cause scaling, reduced strength, poor abrasion resistance and cracking.

4 | NASHWAN HAMID YAHYA AL-EMAD

February 20th, 2009 at 3:18 am

Concrete that Cleans Itself and the Air

After 10 years of development and testing, concrete that removes pollutants from the air as it keeps its surface clean is now available in North America. The product that makes this possible is a patented portland cement developed by Italcementi Group and produced in North America by its U.S. subsidiary, Essroc. The key to the material’s properties is photocatalytic components that use the energy from ultraviolet rays to oxidize most organic and some inorganic compounds. Air pollutants that would normally result in discoloration of exposed surfaces are removed from the atmosphere by the components, and their residues are washed off by rain. This new cement can be used to produce concrete and plaster products that save on maintenance costs while ensuring a cleaner environment.

5 | ROSMAN HUSSIEN

June 15th, 2009 at 4:24 am

i very interested to know detail about kuikcrete and kuikwall

Rosman Hussien
Technical Directtor
Nur Takzim

6 | ashmann

June 25th, 2009 at 3:56 pm

Michigan ) — Any engineer would look at this image and say, “That can’t be concrete!” But it is; and it could represent a way to make bridges and other structures safer and longer lasting.

There is a lot of work being done to improve concrete, right now. And while it is not the most beloved green building material, it has properties that make it eminently useful for engineers and architects for a number of purposes. Given that there is not going to be a sudden moratorium on using the stuff, it’s better to have improvements that can keep from having it go from useful building material to landfill.

Professor Victor Li at the University of Michigan has developed a self-healing concrete that can help alleviate the need for demolition and replacement of concrete after it has been subjected to heavy stress. By devising a concrete that controls the way it cracks under stress, the concrete can withstand tensile strain hundreds of times more than ordinary concrete. Beyond its remarkable flexibility, this concrete can then heal itself, as well.

“In Li’s lab, self-healed specimens recovered most if not all of their original strength after researchers subjected them to a 3 percent tensile strain. That means they stretched the specimens to 3 percent beyond their initial size. It’s the equivalent of stretching a 100-foot piece an extra three feet—enough strain to severely deform metal or catastrophically fracture traditional concrete.”

The new concrete needs only exposure to moisture and carbon dioxide in order to heal the microscopic cracks that are formed after the concrete has been stressed. The cracks expose dry cement in the structure, and this reacts with CO2 and moisture to form calcium carbonate ’scars’ which quickly heal the concrete.

“The professor says this new substance could make infrastructure safer and more durable. By reversing the typical deterioration process, the concrete could reduce the cost and environmental impacts of making new structures. And repairs would last longer.”

Source: http://www.dekalbacademyoftechnology.org

7 | ashmann

July 4th, 2009 at 11:10 pm

South Jordan, Utah) — America’s largest manager and marketer of coal combustion products – is completing the conversion of a wet-handled coal ash facility to a dry ash operation in Monroe, Michigan.

The conversion to dry handling is designed to collect the coal ash before it is placed in a disposal impoundment and to make it available for safe and environmentally beneficial use in the production of concrete.

“Converting wet ash handling systems to dry handling is increasing as an important coal ash management strategy,” said Mike Adams, vice president of Headwaters Resources. “Regulatory changes on the horizon are expected to make conversions like this one even more desirable.”

The wet-to-dry conversion project under way in Michigan is located at Detroit Edison’s Monroe Power Plant – a four unit, 3,200-megawatt power station originally constructed in 1974.

The dry collection equipment is being installed in two phases. The first phase is scheduled to be completed July 15 and includes installation of equipment to collect the coal ash produced in Units 1 and 2 in a dry state, a 4,000-ton storage facility, and truck/rail loading equipment for distribution to concrete producers in the Midwest United States and Eastern Canada. Headwaters Resources is providing $10 million in financing for the project.

The second phase of the project is scheduled to begin in 2011 or 2012 and plans include equipment to collect Units 3 and 4 and an additional 4,000-ton storage silo. When completed, Headwaters Resources estimates that it will collect 400,000 tons of coal ash annually that has previously been placed in the on-site impoundment and anticipates safe re-use of the fly ash in the production of concrete and concrete products.

“Utilizing coal ash in concrete has numerous performance and environmental benefits,” said Adams. “Concrete made with fly ash is stronger and more durable than concrete made with cement alone. In addition to reducing the amount of material going to landfills, coal ash utilization also allows concrete producers to use less cement. Not producing that cement conserves natural resources and reduces greenhouse gas emissions from cement production to the tune of up to 15 million tons last year alone in the United States.”

This is one of many projects Headwaters Resources has undertaken to collect and beneficially use coal ash that was previously disposed. With on-going projects at 103 utility locations and approximately 20 million tons of coal combustion products under management annually, Headwaters Resources is the largest manager of coal ash resources in the United States. Headwaters Resources is also responsible for more than half of the nation’s total sales of coal fly ash for use in concrete applications – an important contributor to reducing greenhouse gas emissions associated with concrete construction. (www.flyash.com)

8 | ashmann

September 30th, 2009 at 5:21 pm

True to its commitment to sustainable development, Holcim Philippines Inc.’s cement plants continue to initiate various community activities to protect and enhance the environment.

Partnering with the local government of the village of Ilang in Davao City, and the Department of Environment and Natural Resources Region XI, Holcim-Davao plant launched its Adopt Ilang River Project last September 15.

Led by chief operating officer Ian Thackwray, Holcim Philippines senior management and Davao plant employees joined students and local government officials in the tree planting activity to protect the two kilometer stretch of Ilang River from soil erosion.

“Global warming affects all of us, and planting a few trees is a simple but effective response,” Thackwray told those who had come to help plant trees.

“If each of us plants even a single tree, it would make an overwhelming difference. I hope the trees we plant today grow big and strong, so they can do the work of preventing riverbank erosion and mitigating global warming.”

“We owe the continuous success of Holcim-Davao to the support of our host communities, among them the village of Ilang,” said Kevin Hughes, vice president-plant manager of Holcim-Davao.

“Our goal is to work with the residents and officials in addressing problems. It is especially important to get the children involved, as everything we are doing is really for their future,” he added.

In another activity of the Holcim-Lugait plant, employees and their families joined in the clean-up of the coast of Iligan Bay last September 5, in line with the celebration of the International Coastal Clean-up Month.

Volunteers spent most of the morning, cleaning up the one kilometer stretch of the coastal area. “It is not just a way of nurturing the environment but also an opportunity for our employees and their families to mingle with each other in a light and festive atmosphere,” remarked Julius Baliog, Holcim-Lugait Mining, environment, corporate responsibility, and administration services manager.

Holcim’s plants are supporting more community projects in the coming months, including medical missions, and the turnover of homes for the underprivileged.

According to the 2009 Dow Jones Sustainability Index (DJSI) results, Holcim remains one of the leading global companies in sustainable development. It has been confirmed as a member of the DJSI World Index in 2009/2010 in the building materials industry.

For seven years, Holcim has been included in both the Dow Jones Sustainability World Index and the Dow Jones STOXX Sustainability Index.

Holcim’s recycling strategy, its human capital development, its corporate citizenship approach, and its engagement with stakeholders received top scores.

Source: http://www.globalnation.inquirer.net

9 | ashmann

September 30th, 2009 at 5:27 pm

Well-known wildlife pathologist Dr. Ward Stone says he has found disturbing levels of mercury and other pollution in the Ravena-Coeymans area and Stone blames much of it on the Lafarge Cement plant there.

Stone, who works for the state Department of Environmental Conservation, says he spent several months testing animals and soil and plants in that area and found levels of mercury two to eight times what he says might normally be expected. But Lafarge says the plant is safe right now and will be even cleaner in four years when the company completes a modernization costing “hundreds of millions of dollars.”

Ward Stone’s employer says it too is concerned about pollution at Lafarge but the state says the levels of mercury cited by Stone “are in fact within the range of what’s already known about soil in New York State.

As with acid rain, mercury concentrations found in fish and wildlife in New York are attributable in part to emissions from dozens of sources outside of New York State.”

By: John McLoughlin

10 | ashmann

September 30th, 2009 at 6:39 pm

Since the invention of Portland cement, there have been many methods put forward for designing concrete mixes. These methods range from simple practical methods where pre-weighed ingredients are added to a mixer and the mix is assessed by eye, and when a suitable looking concrete is obtained, what remains unused is weighed and the mix is easily back calculated; to highly sophisticated methods, where just about every conceivable property of concrete is factored into the design process.

Structured mix design systems started to emerge just before the Second World War when Glanville produced the simple system Road Note No. 4. Concrete Mix Design. This used a series of water/cement ratio curves and idealized gradings to produce a range of low to medium strength mixes, which for many years became the mix designer’s bible.

In the late 1950s, it was followed by Shacklock & Entroy’s Design of High Strength Concrete Mixes and also mix design methods from both the PCI and ACI, in America and Canada. During the 1970s came Phil Owens’ Basic Mix Design, and shortly afterwards the Department of the Environment Mix Design, which essentially replaced the much used Road Note 4.

Since then many methods have appeared including one impressive system developed by Ken Day, to whom the OWICS conference has been dedicated.

Many of these mix design methods rely on tried and tested, so called idealized gradings for combining aggregates. These have been widely used for many years, such that they have been accepted as the norm. With the advent of pumped concrete attention was focused on combining aggregates in such a way as to obtain the maximum possible packing. Many people, including the author, did some work in this field, checking different combined gradings of materials with a Voidmeter; others looked at computer generated models to achieve maximum packing.

However what everyone overlooked was that when the maximum packing was achieved the materials locked together, and lacked the necessary rheological properties to produce a concrete with the correct workability and flow characteristics, to enable it to be successfully transported, handled, placed, and compacted on site.

A few years ago, an American realized that the rheological properties of concrete were uniquely related to the shape and size of all the particles present in a concrete mix, not just the way they were combined together. He started from scratch to produce a new system of concrete mix design that was radically different from anything that had ever been tried before. The result, which is called iCrete, short for intelligent concrete, represents a quantum leap forward in concrete technology.

When the author was first told about a concrete mix prepared with this technology, understandably he was a little skeptical. However when the concrete emerged from the truck he realized that this was a concrete destined to change the industry. It was so perfectly proportioned and could be placed with a greater ease than traditional concrete. In addition it could be easily compacted. Even visually stiff concretes can become energized and flow with ease under the influence of vibration. The unique packing arrangement also enables a very high standard of uniform color and finish to be obtained.

What sets the mix design system apart from other methods is that it selects a degree of optimization such that other important rheological properties such as cohesion and viscosity are not compromised in the process. It is possible to make a range of concretes from 30 MPa to 100 MPa that have identical workabilities, viscosity and cohesion levels, so that although the fresh concrete properties are virtually identical, they can cover a wide range of strength requirements. Very high strengths can be attained, in excess of 200 MPa, with concretes that still maintain their flow characteristics. However, most commercially produced concretes tend to be at or below the 100MPa level.

The mix design process

The mix design process is designed to make the most effective use of the cement by carefully optimizing all the components in the mix to make them function more effectively. This can either result in reduced cement contents, whilst maintaining the plastic and hardened concrete properties of the mix, or higher strengths and enhanced performance can be obtained without any reduction in the cement content. Apart from optimising the aggregate proportions, attention is placed on the rheological properties of the fresh concrete to make it easy to pump, place and compact. One of the difficulties is to convince Engineers, who lack continuous professional development, that concrete with a Slump of 200 mm or a flow of 650 mm to 750 mm is both strong and exceedingly durable.

Also, in order to maximize on the technology, it will be necessary to review the codes and specifications to revise the minimum levels of cement content, which were drawn up in the early 1970s with the introduction of CP110, and have not yet even been amended to take into account of the benefits of superplasticizers, as water reducers, in enhancing the durability of concrete. This process is currently ongoing at this time, but may take several years to filter through the industry.

Initially, material tests are carried out on the ingredients of the mix and the results are applied to patented mix algorithms. The variation in materials is monitored via a database and their interrelationships are continuously updated and monitored. The mixes are designed primarily for cohesion and viscosity. Even where the concrete visually appears to have a low workability it can easily be re-energized by vibration. The concrete is prepared using a pre calibrated amount of water addition at the time of mixing and the workability is controlled by the amount of admixture addition. Sensors monitor and control any variations in the physical properties of the aggregates.

The result is a very high level of consistency batch after batch. This enables only slight variations in workability to be achieved.

Optimized packing

The optimised packing increases the modulus of elasticity of the concrete over traditional concrete mixes resulting in improved stress/strain characteristics. Other significant advantages include reductions in the drying shrinkage by as much as 30 percent over a similar conventional concrete where the water/cement ratios are held constant, and major reductions in creep are also obtained. This can result in a considerable saving in the amount of the steel used in the design, especially in tall building construction.

Another benefit of the mix design is greatly reduced water contents and hence water/ cement ratios of the concrete. Because this virtually eliminates bleeding of concrete mixes, very careful attention needs to be given to covering and protecting the concrete surface from any water loss, as soon as possible after casting. The concrete does not bleed and it does not segregate. Where high walls or columns are cast, there is coarse aggregate present in the mix right to the top of the lift.

In addition, where the concrete is vibrated, the lack of segregation also results in little or no segregation discoloration, thereby resulting in very uniform colored concrete surfaces that also tend to be free of blowholes. This makes the concrete very useful to architects who like to use as-struck concrete surfaces. In addition, its ability to be molded into complex shapes whilst still maintaining a high quality surface makes it an ideal material for use in the production of precast concrete.

Where it is necessary to control the temperature rise in large concrete pours, the use of reduced cement contents, combined with partial cement replacements can result in a significant reduction in temperature rise of between 14°C to 20°C with optimized mixes.

Environmental aspects

Environmental aspects of the concrete include a reduction in greenhouse gases. The cement industry produces about six percent of the annual carbon dioxide emissions in the world. For every one kg of cement produced at least 700 g of carbon dioxide are given off in the production process. While this does not damage the environment as much as indiscriminate cutting down of the Amazon Rain Forest, clearly if the amount of CO2 in the environment can be reduced, it is of benefit to us all.

The optimized mixes produce on average about 27 percent of the emissions as compared with traditional concrete, representing a considerable saving in greenhouse gases. A kilogram of carbon dioxide produces about five m3 of carbon dioxide gas and a truck loaded with normal concrete contributes a significant amount of carbon dioxide to the environment.

However most of this originates from the cement manufacturer rather than the actual concrete production. The UAE produces 2.9 tons of carbon dioxide per year per capita, due mainly to the surge in construction activity, whereas the world average is 0.6 tons per year per capita. The UAE has embarked on building a low carbon city and iCrete mixes are being used as part of this development.

In New York these revolutionary concrete mixes are being used on the 9/11 site for the construction of the Freedom Tower, which is replacing the towers of the World Trade Centre. It is also being used in the Beekman Tower in New York. The architect for the Beekman Tower, Frank Gehry, said he had never seen concrete like this before, and would like to use it on all his future projects.

Technical advantages

Within a decade it is likely that all concrete will be produced using this type of system, because there are significant advantages for all parties in the construction process:

Client

• Reduced construction period
• Time and cost saving
• Low carbon footprint (27% of normal concrete)
• Good publicity – new and innovative technology
• Green alternative at no extra cost
• Less maintenance – longer service life

Contractor

• Designed for workability cohesion and viscosity
• Easy to place and compact and finish
• No bleeding
• No segregation
• Less variability batch after batch
• Reduced finishing times for slabs and floors
• Ease of handling and placing – less labor required
• Optimizes available materials
• Reduced contract period
• User friendly.
• Savings at every stage of the project

Engineer

• Green concrete – effective use of cement, better not lower quality.
• Increased strength for same cement content
• Lower standard deviation for strength.
• Higher modulus of elasticity – reduced section sizes
• Reduced creep – less reinforcement required.
• 30% lower shrinkage
• Lower …
RCP
Permeability
Absorption
• Enhanced durability
• Lower temperature rise
• Less heat of hydration
• Consistent quality batch after batch
• Improved cohesion and workability
• Minimises the amount of steel reinforcement required.

Architect

• High quality finish
• Uniform color
• Good appearance
• LEED and Estidama points for use
• Environmentally friendly.
• Freedom for design and application
• Consistent quality batch after batch

Strength and durability

Compressive strengths are increased over conventional concretes with the same water/cement ratio and flexural strengths of the concrete are about 16 percent of the compressive strength, compared with seven to 10 percent for traditional concrete. Rapid Chloride Permeability tests on plain OPC concretes even without the addition of either slag or microsilica produced values ranging from 503 – 860 coulombs. These are considered to indicate low chloride permeability.

This test is widely used in the Middle East but is really an indication of the ability of the concrete to conduct current and is so variable even with the same concrete that the results need to be assessed with caution. Where slag and/or silica fume are used as partial cement replacements, even lower RCP values can be obtained.

The results from in service production of an iCrete mix over a similar control mix of 40/20-grade result in +five MPa at seven days and +seven MPa at 28 days. Use of the sensors to control non-modified concrete improve the 28day strength by an average of four MPa over standard production concrete. The tighter production control improves the process standard deviation by between one to three MPa.

Conclusion

This mix design technology is an important development that will revolutionize the concrete industry of the future. The consistent quality combined with ease of placing and compaction, together with enhanced finished surface quality, give the technology a very distinct advantage over any of the traditional concretes currently being produced using other systems of mix design.

After an extensive evaluation of the technology, Unibeton took the decision to implement the technology throughout its extensive series of plants throughout the United Arab Emirates. Its customers are highly impressed with the concrete handling and quality.

By: Christopher Stanley

Christopher Stanley is technical director for Unibeton, the largest ready mix concrete producer in the United Arab Emirates. This paper was presented at the OWICS 2009 conference.

11 | ashmann

October 1st, 2009 at 6:26 pm

In 2007, flooding cost the UK 3 billion pounds, and is classed as one of the biggest threats to the country, only second to terrorism according to the MPA.

(UK) — The UK labour party’s conference was used by the Mineral Products Association (MPA) to launch ‘Concrete and Flooding’ its new publication, with a meeting for delegates and industry professionals called ‘Going down the drain?’

In 2007, flooding cost the UK 3 billion pounds, and is classed as one of the biggest threats to the country, only second to terrorism according to the MPA. The MPA is hopeful that its new publication will help create awareness and improve understanding on how flooding is caused, and how it can possibly be prevented, or its impacts reduced, with concrete being the main focus. Being one of the most commonly used construction materials, its important for everyone to be informed of the role it can play to prevent and reduce flood damage.

Andrew Minson – MPA Concrete Centre executive director – said “It is essential that industry recognizes the consequences of climate change and helps to mitigate problems such as flooding, the concrete industry is doing just that. We believe that the party conferences are important audiences for such a vital issue and that the new guidance will make a very positive contribution to improving flood protection in the UK.”

By: Alice Clare (ARI-C News)

12 | ashmann

November 8th, 2009 at 6:48 am

– Scientists at Sheffield Hallam University have unveiled a new form of liquid granite which could replace concrete in certain applications. The granite can withstand temperatures of up to 1100ºC, meaning it could be implemented as a fire-retardant building material.

The ‘liquid granite,’ which is much like concrete, does not explode when it is exposed to extremely high temperatures and is said to have a four-hour fire rating.

The product uses a third less cement than is needed for concrete, and between 30 and 70 per cent of the material is from recycled sources.

The material has already been specified on Olympic Park projects, including the Village.

Professor Pal Mangat, director of the Centre of Infrastructure Management at Sheffield Hallam, said ‘Liquid granite is a very versatile material that can be used in a similar way to concrete. The product replaces most of the cement in standard concrete with a secret formula of products to change the basic properties of the material’.

Source: http://www.blog.emap.com

13 | zambri bin hasim

December 11th, 2009 at 5:40 am

saya mempunya steel slag untuk dijual…

jika ada pihak tuan/puan inginkan steel slag bagi kegunaan projek2 ..boleh menghubungi saya ditalian 0176565602 En.zambri atau email ke hadszam@yahoo.com