Hybrid Fiber Influence on the Crack Permeability of Cracked Concrete Exposed to Freeze-Thaw Cycles

Wei Zeng; Weiqi Wang; Qiannan Wang; Mengya Li; Lining Zhang; Yunyun Tong

doi:10.3390/ma17081819

Hybrid Fiber Influence on the Crack Permeability of Cracked Concrete Exposed to Freeze-Thaw Cycles

Materials (Basel). 2024 Apr 16;17(8):1819. doi: 10.3390/ma17081819.

Authors

Wei Zeng^{1

2}, Weiqi Wang^{1

2}, Qiannan Wang^{1

2}, Mengya Li³, Lining Zhang⁴, Yunyun Tong^{1

2}

Affiliations

¹ School of Civil Engineering and Architecture, Zhejiang University of Science and Technology, Hangzhou 310023, China.
² Zhejiang International Science and Technology Cooperation Base for Waste Resource Recycling and Low-Carbon Building Materials Technology, Zhejiang University of Science and Technology, Hangzhou 310023, China.
³ Laboratory of Mechanics and Materials of Civil Engineering (L2MGC), EA 4114, CY Cergy Paris Université, Cergy, 95000 Paris, France.
⁴ Department of Mechanical and Mechatronics Engineering, The University of Auckland, Auckland 1010, New Zealand.

Abstract

This paper describes hybrid fiber's influence on the crack permeability of cracked concrete exposed to freeze-thaw cycles. A permeability setup and a laser-scanning setup have been designed to measure the crack permeability and the fractured surface roughness of cracked hybrid fiber-reinforced concrete, containing polypropylene fiber and steel fiber, under a splitting tensile load. The results show that, when the effective crack width of the specimens is less than 25 μm, the rough crack surface significantly reduces the concrete's crack permeability. As the crack width increases, the effect of the concrete crack surface on crack permeability gradually decreases, and the crack permeability of the concrete is closer to the Poiseuille flow model. The permeability parameter α derived from the Poiseuille flow model is effective for assessing the crack permeability of concrete. Compared to the modified factor ξ of crack permeability, the permeability parameter α can effectively evaluate and quantify the development trend of crack permeability within a certain range of crack widths. The permeability parameter α of SF20PP2.3, subjected to the same freeze-thaw cycles, decreases by 16.3-94.8% compared to PP4.6 and SF40, and SF20PP2.3 demonstrates a positive synergistic effect on the crack impermeability of cracked concrete. The crack impermeability of SF40PP2.3, subjected to the same freeze-thaw cycles, lies between that of PP6.9 and SF60. The roughness of crack surface (X) and the crack permeability (Y) are highly correlated and follow an exponential curve (Y = 1.0415 × 10⁷·e^-6.025·X) in concrete. This demonstrates that hybrid fibers enhance crack impermeability by increasing the crack surface roughness. Furthermore, the combination of polypropylene fiber and steel fiber effectively promotes the formation of micro-cracks and facilitates the propagation of multiple cracks in the concrete matrix. This combination increases the head loss of water flow through the concrete and decreases the crack permeability.

Keywords: crack permeability; crack surface; hybrid fiber; positive synergistic effect; splitting tensile load.

Abstract

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