High-performance Sika admixtures improve the carbon footprint of concrete, from manufacture to recycling of the building material. This conserves the environment and reduces building costs.

Brücke Tan Vu Lach Huyen in Vietnam
The Tan Vu Lach Huyen bridge in Vietnam

The Tan Vu Lach Huyen bridge opened in fall 2017 is the longest in Vietnam and part of a major port development project in the north of the country. Both the bridge and the forthcoming Hai Phong International Container Terminal include Sika concrete admixtures for high durability.

Serious efforts to achieve more sustainability should be focused on areas where there is much to improve. This is especially worthwhile in the case of concrete. The manufacture of cement – the binding material used in the production of concrete – itself causes 6% of global CO2 emissions, which is higher than the figure for air traffic worldwide.

But this is changing. Sika has the technologies to make this building material considerably more environmentally friendly. “With our products, we are in a position to reduce CO2 emissions from concrete by half and make a decisive contribution toward conserving nature and resources,” points out Michael Danzinger, Corporate Technology Head Concrete Systems.

Sika has big plans for concrete: teams are working on shorter mixing times and better integration of poor-quality aggregates.

Optimally proportioned Sika admixtures make long workability and short curing times possible.

From raw materials to application

If this quantum leap is to be made, concrete has to be optimized over its entire life cycle. It begins with cement production, where Sika has the special chemicals to reduce energy requirements. Major improvements are also brought about by replacing cement with alternative materials such as fly ash from coalfired power plants or slag from the steel industry. This can reduce the cement content of concrete by a quarter to create ecological as well as financial benefits. Sika is a global leader here thanks to Sika® ViscoCrete®. It is also technologically feasible to bind lower-quality aggregates — sand and gravel — to form a homogeneous, premium-grade concrete.

Improvements are also possible in the area of processing. Sika® ViscoCrete® and Sika® ViscoFlow® – two products that assure technology leadership for Sika – can be used to produce concrete with extremely small quantities of water. They also guarantee a very long workability as well as concrete deliveries that are constantly within the defined specifications. Production waste can thus be reduced to a minimum. The significantly higher concrete strengths attributable to the additives also help to reduce concrete consumption as thinner constructions are possible. Sika’s use of accelerators also plays a part in substantially improving the carbon footprint. Since they cure concrete faster, this either partly or fully eliminates the need for high-intensity heat treatments to increase the early strengths of prefabricated products.

50% DER CO2-INTENSITÄT VON BETON KÖNNEN DANK SIKA ZUSATZMITTELN EINGESPART WERDEN

Durability perfected

Concrete is only sustainable when it is durable. Sika makes it possible for a building to be functional for 100 years without major refurbishments. During this time, the concrete must withstand all environmental influences and mechanical stress, as well as salt water or friction caused by suspended particles when a building is exposed to ebb and flow. These stresses are all encountered by the 5.4-kilometer Tan Vu Lach Huyen sea-crossing bridge in Vietnam, which Sika supplied with concrete additive SikaPlast®-257, among other products. “To ensure that the bridge’s 84 spans can resist the forces at play, top quality concrete is essential despite the less than ideal local aggregates,” remarks Michael Danzinger, “and that means low water content, minimal porosity, and no shrinkage.”

When a building reaches its end of life, the concrete it contains is not lost. It can be recycled and – thanks to suitable Sika products – processed as an aggregate for new concrete.