New Concrete Technology

Toby Ware
Concrete had become scarce and a relatively forgotten material after the collapse of the Roman empire until the technology was re-invented by the use of a new form of cement, Portland cement, which is how we know it today.

The word concrete comes from the Latin word "concretus" which means compact or condensed. Concrete was an important construction material in Roman times and was widely used in their buildings. There is, however, evidence concrete was used well before this era with suggestions of it being laid in 5,600 BC.

Nowadays concrete is extensively used throughout the world on a large variety of different constructions including the world’s tallest building, Burj Khalifa's in Dubai. It is constructed of reinforced concrete and in May 2008 it was pumped to a then world record height of 606 metres (1,988 ft), the 156th floor. Construction used 330,000 cubic metres (431,600 cubic yards) of concrete and 55,000 tonnes of steel rebar. The foundations are constructed of a high density and low permeability concrete

There have been many innovations in concrete over the years which have changed its form and improved its properties.

There have been many innovations in concrete over the years which have changed its form and improved its properties. Some of these have not been successful with the defects not becoming evident until later in life. Some of the more recent concrete advances are noted below:

Self compacting concrete

Self compacting concrete does what it says and negates the need to use a compacting vibrator machine. This means it can be used where there is limited or no access and in complex shapes of formwork which may otherwise be impossible to cast, giving a far superior surface than conventional concrete.

Insulating concrete formwork

These are large modular units which interlock to form the basis of the shell of a building. They are then filled with concrete and remain in-situ once it has cured. They are extremely energy efficient and the system is becoming ever more popular in low rise buildings.

Joint-less concrete

Technically some expansion joints have to be formed to allow the concrete to flex. This type of concrete is predominantly used to provide smooth finished floors. Small bits of fibre glass can be added to the concrete mix to toughen the floor and reduce the amount of expansion joints needed.

As buildings are getting ever taller, concrete now has to withstand the extreme pressures of it's own weight bearing down from above. Special mixes can be made, with every batch put through checks to ensure it is consistent and can withstand the certain pressures.

...more and more buildings are constructed of concrete and it is becoming increasingly popular with designers and end users.

An additive is not always required as there can be simple solutions which ensure the concrete sets correctly. When constructing in countries where the temperate can reach 50 °C (122 °F) ice can be added and it is usually poured during the night when the air is cooler and humidity higher. A cooler concrete mixture cures evenly throughout and is therefore less likely to set too quickly and crack.

Concrete has advanced somewhat since the Roman times with poor practices in earlier concrete now realised. This is definitely something which is keeping the building surveyor busy in terms of regular maintenance and complete repairs.

Although concrete is a major contributor to greenhouse gases it is now seen to be an ideal building product as it insulates against the cold and retains the heat. As such more and more buildings are constructed of concrete and it is becoming increasingly popular with designers and end users.

The other important contributor is that structures made of concrete can have a long service life. As long as it is designed correctly, placed well and allowed to cure properly.