Research and Development of Self-Waterproofing Concrete for Tunnel Lining Structure and Its Impermeability and Crack Resistance Characteristics

Abstract

This research paper systematically investigates the combined influence of fly ash, cementitious capillary crystalline waterproofing (CCCW) materials, and polypropylene fibers on the mechanical properties and impermeability of concrete through comprehensive orthogonal tests. Microscopic morphological changes in the concrete induced by different composite materials are examined via scanning electron microscopy (SEM) and X-ray diffraction (XRD) testing. The objective is to facilitate a beneficial synergetic interaction among these materials to develop highly permeable, crack-resistant concrete. Key findings of this study are: (1) The study unveils the impact of the concentration of three additive materials on the concrete’s compressive strength, tensile strength, and penetration height, thereby outlining their significant influence on the mechanical properties and impermeability of the concrete; (2) An integrated scoring method determined the optimal composite dosage of three materials: 15% fly ash, 2% CCCW, and polypropylene fibers at 1.5 kg/m3. This combination increased the concrete’s compressive strength by 12.5%, tensile strength by 48.4%, and decreased the average permeability height by 63.6%; (3) The collective introduction of these three materials notably augments the hydration reaction of the cement, resulting in denser concrete microstructure, enhanced bonding between fibers and matrix, and improved concrete strength and durability.

Comparative Analysis and Safety Evaluation of Shield Segment Structure Model under Surcharge Loading

“…The tunnel lining is composed of segments connected by bolts [50]. A spring is used to simulate the longitudinal and circumferential bolts between segments.…”

Properties and Microstructure of a Cement-Based Capillary Crystalline Waterproofing Grouting Material

“…To improve the permeability of cement slurry, Li et al [8], Mozumder et al [9], Shin et al [10], and Sha et al [11] prepared various ultrafine cement-based grouting materials and established a slurry permeability prediction model based on artificial neural networks. Li et al [12] and Yan et al [13] analyzed the reaction mechanism of acrylic grouting materials and added different types of accelerators to prepare various acrylic slurries with a strong stability and impermeability. Wang et al [14], Wang et al [15], and Liu et al [16] investigated the film-forming status of a high-permeability epoxy slurry and its penetration depth into concrete.…”