Wednesday, May 7, 2008

Cements Types, Use and Strength

Ordinary cement

This type of cement is used a lot today, and is still known as OPC (ordinary Portland cement) ... It is ground up into a powder to form ordinary OPC

Rapid heat cement

They generate more heat in the early stages and can be useful in cold weather concreting. ... as either rapid-setting or extra rapid hardening may be

Low heat cement

Low Heat Cement complies with AS 3972, Special Purpose Type LH/SR. It is manufactured from the ingredients of specially selected cement clinker and ground granulated blast furnace slag, that result in significantly lower heat generation during the process of hydration than the comparable Portland Cement.

Portland blast furnace cement

The granulated slag made by the rapid chilling of suitable molten slags from blast furnaces forms the basis of another group of constructional cements. A mixture of portland cement and granulated slag, containing up to 65 percent slag, is known in the English-speaking countries as portland blast-furnace (slag) cement.

High alumina cement

of High Alumina Cement, Alumina Cement, Refractory Cement, Refractory Materails, ... Density Corundum Bricks, high alumine cement ca50-G5, G7, G9, fused, ca70, ca80

Expanding cement

Expanding and nonshrinking cements expand slightly on hydration, thus offsetting the small contraction that occurs when fresh concrete dries for the first time. Expanding cements were first produced

Quick setting cement

Rapid cure allows for quick access to repaired areas. Garonite anchoring cement sets and expands rapidly, curing twice as strong as concrete in one hour. Use indoors or out
Air & trading cement

Hydrophobic cement

Cement is a hydraulic bonding agent used in building construction and civil engineering. It is a fine powder obtained by grinding the clinker of a clay and limestone mixture calcined at high temperatures. When water is added to cement it becomes a slurry that gradually hardens to a stone-like consistency. It can be mixed with sand and gravel (coarse aggregates) to form mortar and concrete.

There are two types of cement: natural and artificial. The natural cements are obtained from natural materials having a cement-like structure and require only calcining and grinding to yield hydraulic cement powder. Artificial cements are available in large and increasing numbers. Each type has a different composition and mechanical structure and has specific merits and uses. Artificial cements may be classified as portland cement (named after the town of Portland in the United Kingdom) and aluminous cement

White cement

White portland cement is readily available throughout North America. It has essentially the same properties as gray cement, except for color, which is a very important quality control issue in the industry.

The color of white cement depends on raw materials and the manufacturing process. It is the metal oxides (primarily iron and manganese) that influence the whiteness and undertone of the material. White cement is manufactured to conform to ASTM C 150, Specification for Portland Cement. Although Types I, II, III, and V white cements are produced, Types I and III are the most common.

White cements produce clean, bright colors, especially for light pastels. Many different colors can be created by adding pigments to concrete made with white portland cement. Two or more pigments can be combined to achieve a wide range of colors. White cement (or a mixture of white and gray cement) can be specified to provide a consistent color of choice. An even greater variety of decorative looks can be achieved by using colored aggregates and varying the surface finish treatment or texture.

For more click here :- cement manufacturers

Resource :Yahoo Answers

Saturday, May 3, 2008

Cement Sector News - Announcement in Cement Industry

IN his maiden budget speech, the Finance Minister has acknowledged the growth contributed by the industry in the current fiscal and talked of consolidating it further. However the budget fails to do the same.

The direction and thrust in terms of growth and reforms are missing. Unsavoury proposals of the Kelkar Committee have been withheld for post-election period.

Some proposals which are likely to help the construction industry and cement consumption are the continuation of interest deductible on housing loans and exemption of income from housing projects for the construction of residential units till March 31, 2005.

The emphasis laid on the development of physical infrastructure be it roads, airports, seaports and railroads, is definitely the need of the hour.

For the first time, the Government has acknowledged the need for giving a thrust to concrete roads and has accepted the cement industry's long-standing demand for use of long lasting cement over bitumen in road construction.

The announcement of the construction of 48 new roads measuring 10,000 km along with the Golden Quadrilateral, North-South-East-West corridor besides construction and modernisation of four airports and two sea ports will boost the demand for cement.

The announcement that 25 per cent of the new roads would be concrete roads will spur demand for cement.

If the same ratio is applied to the other major road works, an additional 6,250 km of the total 25,000 km would be constructed using cement.

At roughly 3,000 tonne per km, cement consumption would be in the range of 18 million tonne over the next four years.

This is, in addition to the increasing cement demand that the industry has been witnessing on account of a boom in the housing sector.

These measures bode well for the cement industry.

The decision to scrap dividend tax in the hands of recipient and abolition of Long Term Capital Gain Tax (LTCG) for shares bought after March 1, 2003 are good moves.

However, if the LTCG abolition were made applicable with retrospective effect it would have boosted the stock markets.

While acknowledging that rationalisation of excise rate structure and reduction of the multiplicity of rates was integral to the total tax reform process, the Finance Minister has proposed a three-tier excise duty structure of eight per cent, 16 per cent and 24 per cent.

But by increasing excise duty on cement and clinker by Rs 50 per tonne, the Government has made it the highest taxed commodity.

The specific tax at Rs 400 per tonne on cement works out to 30 per cent ex-works, which is not only the highest rate of duty but also a highly retrograde step.

On one hand, the Government is trying to promote infrastructure and housing and on the other, such an increase would make inputs costlier.

Last year, cement consumption in the country was at 110 million tonnes, thus an Rs 50 per tonne increase in excise of would net the exchequer Rs 550 crore.

This amount it seems would be used to balance the cut announced in excise duty on tyres, aerated soft drinks, polyester filament yarn, air-conditioners and motor cars.