Reactive Powder Concrete Mix Ratio and Steel Fiber Content Optimization under Different Curing Conditions

Abstract

In this paper, a practical reactive powder concrete mixture ratio is created on the basis of an orthogonal experiment. Previous studies have combined the compressive and splitting tensile strengths of four categories of reactive powder concrete (RPC) for major materials. These categories include water/binder ratio, silica fume volume content, sand/binder ratio, and dosage of fly ash volume. The optimal mixing proportion of each factor was determined by analyzing the compressive strength of the RPC matrix. For this purpose, steel fiber was used as a reinforcing agent. The compressive and splitting tensile strength test results of steel fiber RPC were analyzed by comparing compound, standard, and natural curing. This was conducted to explore the improvement effect of different steel fiber contents on compressive performance, especially tensile strength of the RPC matrix. According to the results, the optimal steel fiber content was found to be 4% under the three curing conditions. The effect of compound curing on early strength was found to be greater in RPC than by natural or standard curing. However, the effect of late improvement is not obvious. Although standard curing is slightly stronger than natural curing, the performance under the latter can still meet engineering requirements.

Study on Mechanical Properties of Hybrid Polypropylene-Steel Fiber RPC and Computational Method of Fiber Content

“…The results showed that the splitting tensile strength increased from 4.033 to 9.609, 11.944, and 12.896 MPa, respectively when the steel fiber increased from 0% to 1%, 1.5%, and 2% [23]. The results showed that with the content of steel fiber from 0% to 4%, the compressive strength and splitting tensile strength are increased, and the compressive strength of steel fiber to RPC is increased less, and the splitting tensile strength is obviously improved [20,24]. Moreover, the effect of incorporation of different types of steel fibers on the mechanical properties of the RPC is also different.…”

Effect of Hybrid Steel‐Basalt Fiber on Behaviors of Manufactured Sand RPC and Fiber Content Optimization Using Center Composite Design

“…e specific surface area of the steel and basalt fibers is large, and the basalt fibers have a rough surface and high friction coefficient, which increase internal friction resistance and worsen the fluidity of the mixture. A large amount of cement paste is attached to the surface of the hybrid fibers, and the cement paste wrapped around the manufactured sand is reduced [8], thereby increasing the viscosity of the mixture and decreasing workability. With the same amount of steel fibers (A), slump is slightly reduced as the amount of the basalt fibers (B) increases.…”

“…Compared with the nonfiber RPC, the flexural strength of the mixed RPC is improved obviously, because the main factor affecting flexural strength is the bonding force between the fibers and the matrix. In the loading process, because the fibers demonstrate roughness and unevenness, the fibers slip with the matrix under tension and produce adhesion stress, which plays a bridging role and hinders the development of cracks [8], thereby substantially enhancing flexural strength. Given that the RPC hydration reaction at 7 days is incomplete and the bond between the fibers and the matrix is not at its maximum, pulling the fibers out during the bending resistance experiment is easy.…”

“…Currently, the researches on the steel fiber are developing faster than that of other fibers. e addition of steel fiber can significantly improve the tensile properties of RPC and hinder the development of cracks to improve the ductility and toughness of RPC [8][9][10]. A proper ratio of mixing steel fiber can replace part of steel bars in structures, thereby reducing the difficulty and cost of construction [11].…”

Experimental Research on Concrete Beams Reinforced with High Ductility Steel Bars and Strengthened with a Reactive Powder Concrete Layer in the Compression Zone

“…According to the authors of this paper, it can be concluded on this basis that the creation of concrete composite structures with RPC is a particularly beneficial way to use it in practice for both the manufacture of precast elements and the strengthening of the existing ones. Creating OC-RPC composite structures instead of structures made only of RPC is justified in view of the need to reduce costs and carbon footprint due to increased binder consumption and the higher technological requirements for RPC production (e.g., according to [39], the cost of RPC with a strength of 90-140 MPa compared to OC with a compressive strength of 30-60 MPa is approx. 3-5 times higher).…”