Experimental Investigation on the Influence of Strength Grade on the Surface Fractal Dimension of Concrete under Sulfuric Acid Attack

Abstract

The corrosion of alkaline concrete materials exposed to a sulfuric acid environment is becoming more and more prevalent, and its damage assessment is becoming more and more imperative. This study aims to describe the corroded surfaces of concrete with different strength grades (C30, C50, C80) in sulfuric acid environments in terms of their three-dimensional fractal dimension. Three kinds of concrete with varying strength grades, namely C30, C50, and C80, were immersed in a sulfuric acid solution with pH ≈ 0.85 for four distinct corrosion durations, specifically 0, 28, 56, and 165 days, in accelerated corrosion tests. The 3D laser scanning technique was utilized to capture the 3D coordinates of the surface points of the concrete cylinder before and after corrosion. The fractal dimension of concrete’s uneven surface before and after corrosion was computed via the cube covering method, and the mass loss of the concrete specimen was also obtained. The outcomes demonstrate that the three-dimensional fractal dimension provides a new method for characterizing the degree of corrosion deterioration of concrete samples affected by sulfuric acid via laser scanning technology. From the perspective of the appearance, mass loss, and fractal dimension of a rough surface in the sulfuric acid environment at a pH level of approximately 0.85, the degree of the corrosion deterioration of concrete is ranked from high to low as C80 > C50 > C30. These fractal dimensions of the concrete’s corroded surfaces with various strength grades increase rapidly in the initial period. However, as the corrosion time progresses, the growth rate of the corroded surface fractal dimension gradually decelerates and tends towards stability, which accords with the law of exponential function. The widespread belief is that the higher the strength grade of concrete, the better its durability; however, this pattern varies in sulfuric acid corrosive environments. Therefore, based on this research, it is recommended that in extremely acidic environments (i.e., very low pH), more attention should be paid to high-strength grades of concrete.

Experimental Study on the Performance of Glass/Basalt Fiber Reinforced Concrete Unidirectional Plate under Impact Load

“…Glass fiber rebar and basalt fiber rebar are fabricated using glass fiber or basalt fiber as reinforced material, coupled with high-performance resin and high-strength fiber through a pultrusion process. In comparison to traditional steel rebar, they exhibit superior tensile properties, are lightweight, high-strength, corrosion-resistant [21,31], easy to cut, and non-magnetic. The tensile tests were conducted using the WAW − 600D microcomputercontrolled electro-hydraulic servo hydraulic universal testing machine from Jinan Chenda Testing Machine Manufacturing Co., Ltd. (Jinan, China), resulting in measured tensile strengths of 896 MPa for glass fiber bars and 883 MPa for basalt fiber bars.…”

“…Utilizing fiber composite bars in marine and water conservancy projects, in lieu of standard steel bars prone to corrosion and structural failure, can notably improve the endurance and efficiency of such concrete structures [19]. The diameter of fiber bars plays a crucial role in their concrete bonding performance [20,21]. Smaller diameter basalt fiber-reinforced polymer (BFRP) bars can reduce stress transmission length and minimize crack width.…”

Experimental Investigation on Shear Behavior of Non-Stirrup UHPC Beams under Larger Shear Span–Depth Ratios

“…In the context of normal concrete (NC) beam structures, dense stirrups are typically employed to resist shear forces [25,26]. The incorporation of steel fibers offers ultra-high tensile strength to the UHPC matrix, making it possible to eliminate the stirrups of UHPC beams [27,28].…”

Design Approach on Bearing Capacity of the Cross-Bracing with Different Types of Joint Connection in Steel Lattice Transmission Towers

“…Given the relatively high proportion of tower weight attributed to diagonal bracing, achieving optimization of diagonal bracing weight and reduction in tower weight through theoretical and experimental investigation is indeed a feasible endeavor. It should be noted that the literature focuses on the superstructure, and considering the foundation design, the corrosion of groundwater cannot be ignored [25,26].…”