Testing
For a new building material to make the leap from the lab to real-world applications, it must meet the same requirements as conventional concrete. NEbeton has therefore undergone testing for strength, freeze-thaw resistance, resistance to high temperatures, and resistance to aggressive chemical environments. The results so far show that it keeps pace with conventional concrete in key parameters and even outperforms it in some areas.
| Conventional concrete | NEbeton |
|---|---|
| Withstands loads of up to 76.5 metric tons | Withstands loads of up to 76.5 metric tons |
| Aggressive substances destroy it | Resists aggressive substances |
| Cracks at 200 °C | Retains up to 70% of its strength at 1,100 °C |
Strength. Comparable to conventional concrete
One of the material’s fundamental and most important properties is its compressive strength.
With NEbeton, we aim for the compressive strength of standard structural concrete of class C25/30. After 28 days of curing, such material must withstand a compressive stress of at least 30 MPa in testing. NEbeton achieves approximately 35 MPa in testing, so it meets the required value with room to spare. This is crucial news for the material’s use in construction. Replacing cement and using recycled raw materials do not come at the expense of one of the material’s most important mechanical properties.
The test is most commonly performed on a concrete cube with 150-millimeter edges. The cube is gradually loaded in a press until it cracks. The material’s strength is then calculated from the force measured.
In the strength test, the load reached up to 76.5 metric tons.
Lower emissions do not mean compromising on strength
One hundred freeze-thaw cycles
Concrete must also withstand temperature fluctuations, particularly the repeated freezing and thawing of water inside its structure. This is precisely what the freeze-thaw resistance test verifies.
NEbeton has successfully passed 100 freeze-thaw cycles, meaning it meets the requirements for standard concrete of this class.
NEbeton samples are placed in an automated chamber, where the temperature is lowered to -15 °C and the water contained in the sample freezes. This is followed by thawing in a water bath at +20 °C. One such cycle lasts approximately six hours, and the entire process is repeated over and over again.
High temperatures are an area where NEbeton excels
When exposed to a temperature of 1,100 °C, NEbeton retains approximately 70% of its original strength. The process begins by measuring the strength of samples under normal conditions. Additional samples from the same mixture are then placed in a furnace, gradually heated to the desired temperature, and subsequently allowed to cool. Their strength is then measured again. This makes it easy to compare how much the high temperature has weakened the material.
Conventional concrete does not tolerate high temperatures as well as NEbeton. The water in its structure turns into steam when heated and can damage the material from the inside. Furthermore, as the temperature rises, some of its other components also change. Concrete thus gradually loses its strength and, at very high temperatures, may begin to disintegrate. NEbeton has a different, cement-free composition. Its individual components bond in a different way, creating a structure that is simply more resistant to high temperatures.
Acids, sulfates, and road salt. How does NEbeton handle chemicals?
Over its service life, concrete is not only exposed to water and temperature changes. In some structures, it is also regularly exposed to chemically aggressive environments, such as acids, sulfates, and chlorides contained in road de-icing salts.
During testing, samples of NEbeton are therefore immersed in a solution of aggressive substances for extended periods, and changes in their appearance, weight, and mechanical strength are monitored.
Thanks to its composition, NEbeton has a very dense and stable structure that aggressive substances find difficult to penetrate. Finely ground recycled brick also plays a role, helping to fill the tiny pores inside the material. In the future, it could thus find applications, for example, in wastewater treatment plants, sumps, and industrial facilities where building materials are exposed to more demanding conditions.
Conventional concrete contains cement, which, as it hardens, produces substances that can chemically react with acids or sulfates. Such a reaction can gradually weaken the concrete’s structure and lead to cracking or even disintegration.
What does this mean?
Test results show that NEbeton is not only an interesting way to utilize recycled raw materials and replace conventional cement.
It matches the strength of standard concrete in its class, as well as withstanding repeated freezing and thawing, very high temperatures, and exposure to aggressive chemical environments.