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Round up domestic steel prices HC Valve Network: Domestic steel prices continue to rise overall, including tons of cold rolled coils prices rose 150 yuan. CCTV reporter Yang Chao connection below to find details.

Moderator: Steel prices continue to rise, or how much, where relatively large gains?
Reporter: Spot prices of steel in the building last week, rose again in general, including Jinan, Taiyuan, Lanzhou and other markets rose by a larger average increase per ton 100 yuan, Plate prices rise sharply, or the biggest is in Beijing and Tianjin market, up 150 yuan per ton, hot-rolled product prices overall rose 50 yuan per ton, cold-rolled products, the average rose to 150 yuan per ton.

Moderator: Steel prices continue to rise, what is the reason?
Reporter: rising costs push power on the one hand, on the other hand is the demand pull, is mainly two aspects. In addition, one is making the economy take a good demand in the security, on the other hand is a strong ability to shift the cost of some
  Steel Rise in raw materials companies, while the transfer by way of price increases the cost. It is noteworthy that iron ore imports continue to maintain nearly a month is an upward price trend, the current domestic market price of imported ore from 116 to 118 U.S. dollars per ton in the price has reached its highest point during the year than the year lows nearly doubled.

A concrete technology

Hollow core concrete systems coupled with energy efficient TermoDeck technology offer several advantages when compared with traditional systems.

EFFICIENT: Hollow core concrete slabs being used on a building.

In the world of concrete, hollow core systems that have been around for about 25 years in different countries, is now knocking the doors here.

The technology of factory-made concrete slabs for floors and roofs has been in use for a long time. In Kochi, the proposed shopping mall, by the promoters of Dubai's Lulu Centre, at Edappally is likely to have hollow core slabs. For this the company that would be taking up the contract would be setting up a plant here.

Energy efficient

John Durham, Technical Director of Hollow Core Systems (India) Private Limited and TermoDeck International Limited, who made a presentation at the recent national convention of the Builder's Association of India in Kochi, made quite an impression on builders assembled here with his presentation on an energy-efficient system promoted by the company.

According to him, the system promoted by his company has not just hollow core slabs but an energy efficient system too, which goes hand in hand with the hollow core slabs.

The concrete slabs in the required specifications are set in the factory and brought to the site of construction. Fixing of the slab requires just about four workers, said Mr. Durham. A 500 sq.feet. floor can be fixed in a matter of hours, he added. A bigger area may take a day, he added. The traditional process of laying a roof takes days for the arrangements and at least 10 days for the wet concrete to set in. But with hollow core slabs it can be finished in just about a day.

The system is environment-friendly as it totally removes the need of the bamboo props that are required to give support to concrete laying by the traditional method, said Mr. Durham. The high-technology method of making the hollow core slabs reduces the weight of the concrete by 60 per cent. Water content in the concrete is reduced by 70 per cent and the span of the concrete is big.

The casting bed is 1.20-1.40 metres wide, and standard thickness, between 15 cm and 50 cm. No plastering is required on the slabs because of the fine finish, said Mr. Durham. It can straight away take a coat of paint.

The slabs have tubular holes - cores - running through its length. The slabs take its name from this hollowness inside and the main purpose of the hollow core is to decrease the weight. The materials used are comparatively much less, though there is no compromise on strength. The slabs are made on steel strands running longitudinally

The concrete beams between the holes carry the steel rods that provide the compressive stress that holds the slab together under heavy loads.

Workers at Concrete Technology in Tacoma set rebar for the second bridge girder on November 16, 2007. 


Overhead cranes are used to maneuver the steel framing into position before the concrete is poured. 


Positioning the steel framing for the second girder. 


I-90 Easton bridge girder tagged for shipment.



The first girder curing on the Tacoma waterfront. This photo illustrates the "bulb tee" (pdf 634kb) girder design.

Q: We will be supplying ready mixed concrete for a commercial floor project. The engineer of record has added fibers to the project specification. The concrete contractor is now concerned that with this job change, the fibers may slow his placement procedures and has submitted a change order request to place and finish the fiber concrete mix.

Does adding fibers affect the workability of a concrete mix? Do synthetic and steel fibers affect slump?

When fibers are added to a concrete mix design, slump may be affected. But a properly proportioned mix design using fibers should not result in a less workable mix.

A: Introducing synthetic and/or steel fibers can change workability and slump. Any time producers consider adding fibers to a standard mix design, they should prepare a trial mix for the concrete contractor's approval.

According to Bobby Zellers, past president of the Fiber Reinforced Concrete Association and now director, engineering services for ABC Polymer, the physical properties of fibers may affect fresh concrete's slump and/or workability. Zellers identifies three main properties to consider.

The type of fiber is important. For example, Zellers notes that fibrillated polypropylene fibers can reduce the slump and workability more than monofilament polypropylene and nylon fibers. And since steel fibers are rigid, mixes can often have less slump, thus affecting workability.

The quantity of fibers in a mix will definitely affect the slump and consistency. Zellers explains the influencing factor is the increase of surface area from the fibers. In addition to the coarse aggregate, the mortar must also coat the fibers. If the mix's mortar fraction is insufficient, then the effect on the slump and workability will be greater.

Producers must monitor fiber quantity when determining the proportioning ingredients in a fiber-reinforced concrete mix. More fibers require more mortar. Synthetic fibers, when used at 0.5 to 3.0 pounds per cubic yard, typically do not require changes to the mix proportions. In general, synthetic fibers at 0.5 to 1.5 pounds per cubic yard will reduce the slump 1 to 2 inches in a well-proportioned mix. At this dosage level there should be no effect on workability.

But when the fiber dosage reaches 3.0 pounds per cubic yard and above, producers should review the mix proportions. It's best to batch a trial mix to evaluate the proportions of conventional ingredients and the effect of the fibers. At dosage levels of 3.0 or more pounds of synthetic fibers per cubic yard, Zellers suggests including a mid-range or high-range water-reducing admixture. For steel fibers, He suggests that when the dosage rate reaches about 40 pounds per cubic yard, producers should consider adding a water-reducing admixture and modifying the mix design.

The length of fibers affects slump. Researchers have reported that longer fibers will reduce the slump to a greater degree than shorter fibers. Zellers says that a 1 ½-inch-long fiber will reduce the slump more than a ¾ -inch-long fiber of the same type, at the same dosage level.

Zellers cautions that a reduction of slump does not also result in a less workable mix. His experience with fiber-reinforced concrete suggests that with a properly proportioned mix design, fibers will have little or no effect on the workability. He backs this conclusion by referencing the effect fibers have on the four properties of the plastic concrete found in the ACI 116 definition of workability: ease of mixing, placing, consolidation, and finishing.

If properly introduced into a properly maintained mixing system, synthetic fibers will homogeneously distribute within three to four minutes in a truck mixer. Zellers says the key is to avoid adding bags of fibers at the same time as the cement. The mixing of steel fibers does require special attention.

Fiber-reinforced concrete is as easy to place as a mix without fibers. According to Zellers, researchers have reported that mixes containing fibers will have a lower pump pressure than the same mix with no fibers. When the mortar fraction of the mix is sufficient to coat the coarse aggregate and fiber, coarse aggregate remains suspended, thus reducing friction at the pipe's wall.

In a properly designed concrete mix, consolidation of the fiber-reinforced concrete is no different than concrete without fibers. However, when the contractor over-consolidates the mix, the fibers can quickly separate from the coarse aggregate. Some would view this as poor distribution of the fibers where, in fact, it is a result of poor consolidation practices by the contractor.

When finishing a fiber-reinforced concrete slab, Zellers says contractors should not experience any significant delays or quality concerns. Zellers observes that a vibrating or laser screed actually helps encapsulate fibers at the surface of the slab within the mortar, creating a more durable surface.

As the Tanzania government takes a step on irrigating more land to boost production, lack of good contractors remain a challenge of which it has contributed many districts not starting the irrigation construction. So far only one district out of 162 districts has managed.

Modern irrigation becomes a reality in Bahi as Israelis arrive to pilot drip methods

• Tshs1.6bn worth of irrigation schemes to be handed over by November

• Local contractors say government tendering condititions too stringent for them

By Angel Navuri,Bahi

Local farmers and government experts have joined hands to ensure construction works for irrigation schemes in Bahi district take off at record speed. The District Commissioner, Mrs Betty Mkwasa, is one woman in a hurry and is not sparing any efforts to ensure Kilimo Kwanza in Bahi becomes a reality, whatever the obstacles.

No meaningful agricultural development can be expected in semi arid areas without irrigation but competent firms that can set up the required infrastructure are not readily available. Hence the need to creatively assemble teams that comprise experts borrowed from the central government, local agriculture officers and peasant farmers themselves who are the intended beneficiaries of the irrigation schemes.

These creative efforts have seen the birth of new irrigation schemes in Bahi namely Mtitaa which is costing Tsh400milion, Chikopelo that will consume Tsh606 million and Mtazamo whose cost is Tsh675 million.

Besides these budgetary disbursements from the government, another major contribution whose cost has not been computed is the labour provided by the local farmers in clearing the paths and helping in the excavation of the canals.

Speaking to The Guardian’s Kilimo Kwanza that visited the irrigation schemes, the District agriculture officer Sylvester Kashaga said that the constructions are in the last stages and they will be handed over by November.

The farmers are involved in the process of the construction so that they can also gain guidance from the contractors and the agriculture officers. It is a two-way process, for they also provide local knowledge to the experts as construction goes ahead.

According to Mr Kahsaga, Bahi was supposed to have 10 irrigation schemes but they have decided to have four big irrigation schemes instead of having many of them that have a limited capacity of serving.

Kashaga said that the establishement of the schemes it’s for boosting rice production in the interim, then later they will have other crops included too. The projects will be depending on a combination of the rivers and rains as a source of supplying water.

“For this irrigation schemes the famers will depend more on the river water and the rains, “he said, explaining that it will be seasonal farming. Besides harvesting the rains, water will also be obtained from the rivers Bubu, Mtonga, Mkambala, and Makorongo.

Besides the volunteer labour from the farmers, the District Agriculture Officer also highlighted the major commitment of the District Engineers and technicians who made the as irrigation construction possible. “There is money for irrigation development for all districts in this country but why some have not taken off is partly due to lack of such committed technical personnel as the ones we have in Bahi,” he explained

The district commissioner Betty Mkwasa said that her district managed to get good contractors after they advertised in the media and scrutinised the qualifications of the applicants.

Mkwasa also disclosed that Israeli contractors will be coming on board very soon and 20 hectares have already been earmarked for them to start a pilot drip irrigation schme with several farms. This will be just the first phase of a project that will cover 116 hectors for the entire drip irrigation pilot scheme.

Asked how she managed to attract so much money (over a billion shilings) to the district’s irrigation scheme, Mkwasa said they got the funds by writing good, convincing proposals by the help of their agriculture officer. “We were not given the money that easily,” she recalled. “For your district to benefit, you have to submit proposals that are good and convincing of you are to the needed funds for construction,” she said “I think we got more money this year than any other ditrict for irrigation,” she said. “But we still need more because irrigation construction is quite expensive.”

Mkwasa also said that plans of drilling boreholes for farming are underway since the area is so dry and there will be specific areas since many of the areas have salty water.

Speaking on the shortage of seeds, she said in her district it is not yet a problem. The DC reiterated that her ban on planting maize in Bahi is still in force and “serious action” awaits anybody who dares violate it.

“Changing the mindset of the people to agriculture is a challenge leadership at all levels in the country is still facing,” she said. The DC slapped a ban on the planting of maize in her district earlier this year, saying it is time residents realised that there are other, more profitable crops – including rice - to grow. She also ordered the confiscation of fertiliser obtained under the subsidy scheme that may be found lying in people’s homes instead of being taken to the gardens.

Extension agriculture officer Seshika Mchomvu expressed the confidence that from now on, the Bahi farmers will produce more than enough for subsistence because of the irrigation schemes that that have been started.

He said that at first farmers could not produce enough because the water could not move to the farms as a lot was sinking to the ground but now it will be easy as the water flow is technically controlled.

Irrigation officer Nicolas Lipundu said that the renovation of the dams will help in collecting more water and it will help in controlling more than before.

He said that at first the water held by one dam was 56,000 cubic metres but after renovation the dam can now hold 60,000 cubic metres.

According to Lipundu before renovation of the dam and construction of the irrigation schemes the water used to “pass through” and not getting to the farms but now the water will be controlled and directed to where its needed.

He said to further boost the irrigation capacity, a survey tp precede drilling of boreholes will start soon as to avoid from getting salt water that is not good for irrigation.

A local farmer, Mr Hassan Abubakar said that they didn’t expect that irrigation construction could become a reality, and can hardly believe their good luck.

He expressed satisfaction that in addition to providing more water for farming, the irrigation scheme actually controls the floods, something they had never expected to see in their lifetime.

Abubakar noted that right now the framers are happy and are ready for serious farming and are fearing that they might produce too much produce for the available market. Speaking on behalf of the other local contractors, Contractor Christion Kaguo of Kaguo Business Enterprise CO.LTD said that the construction will be handed over by November.

But Kaguo urged the government to review its irrigation contracts guidelines which he said have a lot of limiting regulations that many local contractors are failing to meet.

“We have good contractors too in the country but the government should review its irrigation contracts as there are so many issues to be tackled. This has lead to many of contractors not being interested in applying for the irrigation contracts,” he argued. “That’s why the government is facing a challenge of getting good contractors