As the knowledge, testing and experience of using fibre-reinforced concrete continues to grow for concrete applications, their successful use and benefits are now being fully realised through projects including floor systems, precast concrete, walls, shotcrete, and pavement systems. However, many questions continue to arise from ready-mix producers and contractors who are still learning the benefits of how fibre-reinforced concrete works and the slight changes to concrete mixtures, finishing techniques, placement methods, and testing requirements that come with using this composite material.
Euclid Chemical has created a series of Technical Bulletins on a variety of topics related to the successful use of Fibre-Reinforced Concrete (FRC). These documents are provided as a service to the Ready-Mix Concrete and Concrete Contracting community to answer questions that often arise on topics such as fibre types, mixing tips, finishing methods, pumping, and joint spacing.
The most common questions that arise from the construction community on the use of fibre-reinforced concrete include the topics as described here:
How Does Fibre Use Impact Slump Or Air Content Of Concrete?
Fibre types, dosages and mix design all play a role in how the slump, or measured flow, of concrete will behave. However, when combined with proper admixture use, fibre-reinforced concrete can be mixed and placed with the same consistency as normal concrete. Air contents are generally not affected by fibre use unless additional water is added to a mix to increase slump.
Are Steel Fibres And Synthetic Fibres Used In The Same Applications?
Micro-synthetic fibres, which have been around for over 40 years, are generally used for the control of plastic shrinkage cracks only and are used at low dosages. Steel fibres and macro-synthetic fibres are typically used at higher volumes and can be considered for use in similar applications to replace temperature and shrinkage reinforcement and limited structural applications.
How Can Fibre Balling And Other Mixing Problems Be Eliminated?
Most commercially available fibre types can be successfully mixed and placed in concrete provided the correct concrete mix design has been used and recommended fibre addition methods, as directed by the manufacturer, are followed.
What Are The Common Issues And Remedies For Pumping And Finishing FRC?
Fibre-reinforced concrete can be easily pumped and finished, provided that a correct mix design is developed prior to fibre addition and that precautions are taken to not over-finish a concrete surface. There is no guarantee that fibres will not be visible on a concrete surface but with proper techniques and fibre selection, finished surfaces can be achieved with the same appearance as plain concrete.
Can Floor Joint Spacing Be Extended With Fibre Use?
There are successful examples and significant research in the concrete industry that support the increase of control joint spacing in floor design when using fibres, specifically macro-synthetic and steel fibres. However, most of this work is also in combination with improvements in concrete mix designs using advanced chemical admixtures and proper placement and curing practices.
Article contributed by Jennifer Crisman, Director of Marketing Services at Euclid Chemical.
For over a century, The Euclid Chemical Company has served the global building market as a worldwide quality supplier of specialty products for the concrete and masonry construction industry. Tremco CPG is proud to supply Euclid Chemical’s wide range of specialty products for new construction or restoration projects across the Asia Pacific region. Our expert team is on hand to provide you with complete solutions for your next concrete project, get in touch with them today.