Abstract

Introduction

Material and Methods

Results and Discussion

Conclusions

References

Abstract

To explore the effect of multi-scale polypropylene fiber (PPF) hybridization on the mechanical properties of roller-compacted concrete (RCC), the early-age (3, 7, 14, 28 days) compressive strength, splitting tensile strength and uniaxial tensile test of RCC reinforced with micro-, macro- and hybrid polypropylene fibers were investigated. Then, the tensile stress–strain curve of polypropylene fiber-reinforced roller-compacted concrete (PFRCC) and the corresponding tensile parameters were obtained. The uniaxial tensile constitutive equation of PFRCC and fiber hybrid effect function was also proposed. Finally, the enhancement mechanism of fiber hybridization on mechanical properties of RCC was analyzed. The results indicated that the strength and toughness of PFRCC improved with the incorporation of PPF, showing obvious plastic failure characteristics of PFRCC. Before curing the concrete for 7 days, micro-PPF played a major role in strengthening RCC, while macro-PPF played a major role in reinforcing concrete after that. Moreover, the tensile strength and toughness indexes of multi-scale PFRCC performed the best, indicating the positive hybridization of three types of PPF. The proposed PFRCC uniaxial tensile constitutive equation and fiber hybrid effect function based on existing researches were also well matched with the experimental results

Introduction

Roller-compacted concrete (RCC) is commonly used in a variety of road pavements, pavement bases and et al. (Lopez-Uceda et al., 2016), which is known for saving cement, early high strength and reducing construction time. However, RCC also includes some disadvantages, such as low tensile strength, poor crack resistance and toughness, limiting its development in engineering structures (Bayagoob & Bamaga, 2019; Lam et al., 2018). Previous studies (Ahmad & Umar, 2018; Benouadah et al., 2017; Marushchak et al., 2019; Yoo & Banthia, 2016) have shown that the addition of fibers can effectively control the formation and development of cracks in concrete, and greatly increase the strength and toughness of concrete.

In practical engineering applications, there are many kinds of fibers, among which steel fiber and polypropylene fiber (PPF) are the most popular (Hussain et al., 2020; Madhkhan et al., 2012). Steel fiber has high elastic modulus and stiffness, which is widely used for its good strengthening and toughening effect on concrete. However, its development is limited by its deficiencies of high cost, poor corrosion resistance and inconvenient construction. PPF is often divided into micro-PPF and macro-PPF according to the size. Micro-PPF can restrain the early cracks of concrete significantly, but it has no obvious reinforcing and toughening effect on concrete. Macro-PPF, also known as the candidate material of steel fiber, has comparable reinforcing and toughening effect with steel fiber (Yin et al., 2015). Many researches showed that the hybrid fiber-reinforced concrete can make different fibers complement each other and promote the mechanical properties of the concrete matrix (Turk et al., 2021; Yao et al., 2003).