Owing to its enhanced strength, ductility, and resistance to harsh environments, increasing research attention has been paid to alkali-resistant glass fiber reinforced concrete (ARGFRC). This paper presents experimental studies concerning the effects of fiber content on the mechanical properties and microstructural characteristics of ARGFRC. The amount of glass fiber was considered at levels of 0.0, 0.3, 0.5, 0.8, 1.0, 1.3, and 1.5 of the concrete volume. The compression, flexural, impact resistance, scanning electron microscopy, and energy dispersive spectroscopy tests were conducted. The flexural load-deflection curve, flexural strength, flexural toughness index, flexural fracture energy, postcracking stiffness, postpeak stiffness, and impact resistance energy absorption were obtained. Then the changing law affected by fiber content on these mechanical properties was further analyzed, and the corresponding equation was fitted. When fiber content was 1.5, the flexural toughness index I₅, I₁₀, and I₂₀ values were 4.0, 5.9, and 8.9, respectively, and increased by 3.07.9 times. Glass fiber incorporation could increase the ductility and delay the brittle failure when the fiber content reached 0.8. The largest postcracking stiffness was calculated at 36.174kN/mm with a fiber content of 0.8. The higher the fiber content, the larger the postpeak stiffness of the tested beams. Impact resistance test results demonstrated that the optimum fiber content was 1.3. As the fiber content increased, the effect of the concrete grout on the fiber packaging decreased, according to the scanning electron microscopy analysis. The energy dispersive spectroscopy observation proved that adding a certain fiber content did not affect the concrete hydration reaction.

The mechanical properties of High-Performance Self-Compacting Concrete (HPSCC) are strongly influenced by its pore structure, but the impact of varying water–binder ratios (W/C) on this relationship remains unclear. To address this, the present study investigates HPSCC with W/C ratios ranging from 0.19 to 0.23, aiming to elucidate the connection between pore structure, fractal characteristics, and mechanical performance. Through a combination of compressive strength testing, low-temperature nitrogen adsorption, and Scanning Electron Microscopy (SEM) observations, this study reveals key insights. First, compressive strength initially increases with a decreasing W/C ratio but plateaus beyond W/C = 0.21, identifying an optimal range for balancing strength and workability. Second, the pore structure of HPSCC is characterized by cylindrical, ink-bottle, and planar interstitial pores, with significant fractal characteristics. Notably, the fractal dimension decreases as the W/C ratio increases, indicating reduced pore complexity and improved homogeneity. Finally, a strong linear correlation (R² > 0.9) between the W/C ratio, fractal dimension, and compressive strength provides a predictive tool for assessing HPSCC performance. This study concludes that the internal pore structure is a critical determinant of HPSCC strength, and the identified optimal W/C ratio range offers guidance for mixture designs. Additionally, fractal dimension analysis emerges as a novel method to evaluate HPSCC’s microstructural quality, enabling predictions of long-term performance and durability. These findings contribute to the scientific basis for designing high-performance concrete materials with improved mechanical properties and durability.