Abstract
This research studied the influence of three types of open (short-straight, long-straight, semicircular) and three different shapes of closed steel fibers (triangular, rectangular, circular) with different fiber contents by volume (0, 0.5%, 1%, 1.5%, and 2%) on the working and mechanical performance of reactive powder concrete (RPC). The results indicated that (1) the number of steel fibers and the enclosed area formed by closed steel fibers would remarkably impact the performance of RPC; (2) the semicircular fiber improves RPC’s strength the most among the three open shapes; (3) the short-straight fiber works more effectively than the closed steel fibers; (4) the circular fiber works the most efficiently in improving RPC’s mechanical performance while the triangular ones have the least effect among the three closed steel fibers; (5) both the closed and open steel fibers improve their compressive strength more than their flexural strength; (6) the closed steel fiber works more efficiently in improving the flexural strength but less efficiently in improving the compressive strength; (7) the open steel fibers enhance the mechanical performance of RPC via their anchoring performance while the closed steel fibers work by confining the concrete; (8) the hybrid utilization of steel fibers improves RPC’s mechanical performance to a higher level via combing the advantages of open and closed steel fibers.
Highlights
The curves show that the increase of steel fiber content decreases the fluidity, and the shape of the fiber has a different influence on the fluidity of the reactive powder concrete (RPC)
The greater the enclosed area formed by the closed steel fibers, the higher the compressive strength of the RPC
The conclusions are summarized below: (1) The results show that the geometrical difference and the enclosed area formed by closed fibers have a significant influence on the fluidity, flexural strength, and compressive strength of RPC
Summary
The development of concrete with high mechanical performance and superior durability is of great necessity [1]. The addition of steel fibers in reactive powder concrete (RPC) or ultra-highperformance concrete (UHPC) is a common method to improve its strength, toughness, energy absorption capacity and ductility after crack formation [2,3,4,5,6,7,8,9]. RPC or UHPC is a type of construction material made of a high content of cementitious materials and fine aggregate with a low water/binder ratio [2]. Steel fibers can improve the mechanical performance of RPC but can effectively restrain the development of cracks and provide post-cracking strength and toughness, increasing the service life [10,11]. The commonest shapes include round-straight, crimped, dumbbell, end-hooked, and twisted
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