Posted by José María Vaquero - 02 July, 2018
MasterFiber synthetic fibers in concrete prove themselves compared with steel and optimize the production process
To use a Swiss image, fibers in concrete are like the cherry (liqueur) in cheese fondue – a little goes a long way. The right fibers are almost like the secret ingredients in a traditional recipe. They are often surprisingly easy to use and have a tremendous effect. They are simply indispensable.
Prefabricated concrete element manufacturer Tschümperlin from Küssnacht in the Swiss canton of Schwyz wanted to take advantage of the effect of the right fibers at the same time as improving its production process. Tschümperlin produces concrete, casts it in the shape required, and supplies the finished concrete elements to its customers. The decisive factors are perfect surfaces and generally impeccable results – which is where concrete admixtures can help. In general, the objective is to deliver the prefabricated concrete elements to the customer in the best possible condition. In addition, the admixtures must be easy to mix with the concrete and bring economic benefits. For this reason, Tschümperlin contacted our Master Builders Solutions experts and requested them to optimize its concrete formulation.
Analysis shows: an alternative to conventional steel reinforcement is possible
To lay the foundation for this optimization, the first step was to carefully analyze the objectives and technical possibilities of Tschümperlin. On-site, the technical service experts from Master Builders Solutions soon identified potential for improvement. They found that the company had opted for steel reinforcement for its concrete and had accepted the resulting disadvantages, including the high weight of the reinforcement and surface rust spots caused by corrosion of the steel. They suggested an alternative that was both effective and efficient: the synthetic fibers in the MasterFiber series from Master Builders Solutions.
Advantages of MasterFiber synthetic fibers
“Concrete is well-known for its brittle behavior, which is why reinforcement is essential. For this reason, Master Builders Solution has developed a comprehensive range of fibers that distribute stress and tensile forces within the material and ensure the ductility required as an alternative to conventional secondary reinforcement with steel,” says Christoph Hahn, fiber expert from Master Builders Solutions. “This way, the cracking and rupture behavior of the concrete can be improved and the combination of concrete and reinforcement demonstrates a generally more elastic material behavior.” In addition, fibers reduce the tendency of the concrete to crack as a result of plastic shrinkage, shrinkage during drying, and temperature gradients. Plastic fibers have a further advantage if surfaces with an immaculate appearance are required, as in the case of Tschümperlin: plastic fibers do not corrode and therefore do not cause any rust spots on the concrete surface.
Practical test with support from Master Builders Solutions on site
Following the analysis and some structural design calculations, the application technicians from Master Builders Solutions turned to practical tests together with the Tschümperlin team. The casting of concrete elements for light shafts was to show how much fiber material per cubic meter of concrete was needed to obtain the reinforcement effect required. It was decided to use MasterFiber 246 polypropylene macro-fibers and it was found that the best technical and economic results could be obtained with the addition of six kilograms per cubic meter.
In addition, the admixture MasterGlenium ACE 404 was added to the concrete. As a result of its high effectiveness, this is the ideal admixture for reinforced concrete plants producing self-compacting concrete with high early strength and prestressed concrete. This admixture allows the production of concrete with low water/cement ratios and durable concrete with high early and ultimate strength values. With MasterGlenium ACE 404, it is possible to produce extremely stable concrete as stability is actively increased and sedimentation properties are reduced.
Technical and economic benefits
In addition to improved results as a result of the reduction in cracking during curing, the MasterFiber plastic fibers also allow the optimization of production processes. The plastic fibers are easy to mix with the concrete, the total weight to be transported is significantly lower and the additional loading of equipment by the steel is avoided. The cost-benefit compared with conventional steel reinforcement is also significant, amounting to about 40 percent.
Scientific evaluation to follow
The final results of tests with the light shaft elements are now being scientifically evaluated at the University of Kaiserslautern. In Küssnacht, Tschümperlin is highly satisfied with the on-site support and the professional approach of the Master Builders Solutions team. The Tschümperlin team is confident that the University will confirm the results of the joint tests.
The photos below show the tests carried out with light shaft elements at Tschümperlin and also give an idea of the work of applications technicians from Master Builders Solutions.