Materials Development of Steel-and Basalt Fiber-Reinforced Concretes
Concrete is a structural composite material with excellent properties when subjected to compression. But the poor ability to resist tensile stresses forces the concrete to be used with reinforcement. Commonly, large continuous steel bars have been applied as reinforcement since mid-1800s to carry the tensile loads. Placing the steel bars takes many man-hours, which contributes to a significant part of the total concrete costs. By eliminating the reinforcement part of the construction work, the costs can be reduced considerably.
Fibers have been incorporated into building materials since ancient times to improve the properties. Today, fibers are incorporated in concretes to improve certain properties of this material. They are added to enhance the ductility of the concretes. Additionally, the tensile and the flexural strengths of the material are enhanced. The crack widths and their propagation are decreased by the insertion of fibers.
Research over the years have shown that fiber reinforcement has sufficient strength and ductility to be used as a complete replacement to conventional steel bars in some types of structures; foundations, walls, slabs. Fibers are also used in beams in combination with conventional reinforcement which increase the capacity and the stiffness of the concrete.
The technology that is available today has made is possible to consider fiber reinforcement without the use of conventional steel bars in load carrying structures. For this to be a reality, the fibers must be distributed and oriented as expected, which is difficult. If fibers can be used without the need of steel reinforcement bars, the reinforcement part of the construction work will be eliminated. Hence, the construction costs will be significantly reduced.
In recent years, a project within COIN has set the aim to develop a high tensile strength all-round concrete which exhibits a residual flexural tensile strength in the range of 10-15 MPa and that can be applied in load carrying structures. This MSc-thesis is a part of this work and it has consisted of testing fiber-reinforced self-compacting concretes with different types and contents of fibers, namely steel fibers and basalt fibers. The different concrete mixes were tested and the corresponding fresh and hardened concrete properties were evaluated and compared.
Based upon the results achieved in these experiments, the conclusion was taken of whether or not the different concrete mixes could be used for the purpose the COIN project was aiming for.
Place, publisher, year, edition, pages
Institutt for konstruksjonsteknikk , 2013. , 160 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-24224Local ID: ntnudaim:10300OAI: oai:DiVA.org:ntnu-24224DiVA: diva2:702889
Kanstad, Terje, Professor