It ensures strong foundations and big statements: concrete is everywhere–and has plenty of pros in light of new construction requirements.
Almost every building uses it: Concrete is a proven construction material. Even the Romans used concrete (mixed from burnt lime, sand, water and, at times, brick dust or volcanic ash) in the construction of their aqueducts and other structures. Around the year 125, they made the Pantheon out of concrete, which is still one of the best preserved buildings of Roman antiquity.
Since then, concrete has steadily evolved and is now a standard in the construction industry. The robust building material enables stable and waterproof foundations and strong walls. Because concrete stores heat, buildings constructed of solid concrete have a balanced indoor climate. Concrete components – like all solid building materials – are ideally suited to protect against airborne sound.
Concrete is durable and requires little maintenance thanks to constantly improving formulations. Buildings constructed of solid concrete are more resistant to hazards such as fire. In earlier centuries, entire cities were destroyed by major fires because the fire ate its way unhindered through the wooden structures. Today, high demands are placed on wood in construction in order to avoid such disasters. However, as an organic material, wood contributes to the fire load unlike concrete. Concrete does not require any special proof of non-combustibility and is classified in building material class A1 (non-combustible).
Load-bearing capacity and freedom of design
High fire temperatures can affect the load-bearing capacity of steel components. When steel and concrete are installed together, the concrete coating protects the steel reinforcement from reaching critical temperatures in the event of fire, which could affect its load-bearing capacity.
Concrete can take on beguiling forms like the “Petal Roof” of hypar shells at Los Manantiales in Mexico by Félix Candela or the curved concrete and polyester structure at the Heydar Aliyev Centre in Baku by Zaha Hadid. Formwork can be used to make concrete almost mirror-smooth or with textures such as a wood look. And elastic formwork inserts can bring any design into concrete, from wood, stone or ribbed structures to fantasy textures, photos and lettering.
Concrete and sustainable construction
The fact that concrete is ubiquitous today has a lot to do with one of its key ingredients: cement. It makes concrete strong and durable with its calcium silicates and calcium aluminates.
During production CO2 is released from the raw materials – this process accounts for a large proportion of the emissions in cement production. To minimize these effects, three strategies are being pursued:
Use of alternative raw materials to reduce the proportion of Portland cement clinker
Optimization of the process technology to increase energy efficiency
Use of alternative fuels in production to replace fossil fuels and avoid CO2 emissions
Properly manufactured and installed, concrete is a very durable building material that guarantees high building utilization phases and conserves resources in the long term. In addition, it absorbs some of the CO2 again during this long utilization period.
Unlike other building materials, concrete is usually sourced from the immediate environment. On average, there is a concrete plant within a radius of 15 kilometers of a construction site, which keeps transport distances short and the associated emissions low. It is also possible to produce concrete directly at the construction site. When building with wood, the material is usually sourced from greater distances, and imported wood in particular is subject to long transport distances.
Water is indispensable not only in the production of concrete, but also for cleaning equipment, tools and the mixing drums in transport vehicles. The cleaning water is collected and recycled at concrete plants in specially equipped treatment facilities to conserve resources and protect the environment.
The processing of mineral construction waste is also playing an increasingly important role in meeting the requirements of sustainable construction. Pure concrete rubble is 99% recycled. 87% of construction waste, consisting of concrete mixed with other mineral materials (such as bricks, tiles and ceramics), is recycled
Recycled aggregate, produced in waste management plants, partially replaces crushed natural stone or gravel. There are precise specifications governing such recycling. It is regulated in the DAfStb guideline: Concrete according to DIN EN 206-1 and DIN 1045-2 with recycled aggregates according to DIN EN 12620.