Precast Concrete Products

IS CONCRETE REPLACING STEEL?

Posted 6 June 2008

With the astronomical increases in steel prices world wide, is steel losing market share to alternative materials? This question is especially pertinent for South Africa where increases enforced on industrial users can only be described as irresponsible.

In South Africa the price of steel has risen a monstrous 100% in the first half of 2008 only. This happened on top of handsome yearly increases in the previous several years, which easily beat reasonable inflation rates, even for South Africa. It can be said that, since Iscor sold out to international business in 2003, the price of steel has increased three to four fold.

The cost of concrete, while also subject to inflationary pressure, has on the other hand been far more regular. All the components of concrete including cement and aggregates are locally sourced and locally used. Concrete and its raw materials have not globalized in the way that steel has and have not tracked higher world prices. World cement prices are favourable and bagged cement has recently been imported competitively on a small scale to supplement local supply for South African builders.

With fabricated steel now costing in the order of R 25.00 per kg and fabricated concrete about R 1.50 per kg including some reinforcing steel, concrete has a very clear price advantage. Concrete also has other advantages over steel.

Advantages of concrete over steel

• Concrete is much cheaper per unit mass than steel.
• Concrete does not corrode like steel and can mostly be left unpainted;
• Concrete has no scrap value and is not being stolen to be resold. Concrete is also rather heavy and very difficult to move.

Because it used to be strong and cheap, steel has traditionally been a most popular structural manufacturing material. It is not so cheap anymore and modern developments in concrete now see strengths
comparable to that of steel. The strength of concrete as a material is
essentially in compression. As it is, concrete lacks tensile strength which can be seen as a drawback when it comes to items requiring bending resistance. To make up for this, concrete is reinforced by casting reinforcing bars (rebar) into positions where tensile stresses occur. Rebar is steel but the quantity used is but a portion of what would have been required if the whole thing was made of steel.

Why, if the advantage is so obvious is concrete not used much more?

Because the situation has only changed recently and because there is an established culture of steel. This culture has inertia or resistance to change and it includes habits, established skills, know how and supply infrastructure. Change will take place gradually rather than overnight.

Precast concrete

The advantage of precast concrete over cast-in-place concrete is in that a ready-for-use product is manufactured in a factory and delivered to the customer. The customer does not have to do his own formwork, moulds, mixing, casting and finishing off. Nor does he have to think about reinforcing or worry about design or analysis. The product is provided all inclusive. In a factory environment quality and production cost is more controllable.

Vanstone, in collaboration with its customers, designs and manufactures specific products according to the customers’ needs. The people at Vanstone enjoy the challenge of developing new products and find it exiting to see it work for the customer. Many of Vanstone’s now standard products were once such custom-developed products and now serve a wider base.

Invitation

If you think that your application or problem may have a precast concrete solution, please contact us and we would be very pleased to discuss it with you, do a provisional design and quote for the manufacture of it.