Rock Wool Fiber-Reinforced and Recycled Concrete Aggregate-Imbued Hot Asphalt Mixtures: Design and Moisture Susceptibility Evaluation

Abstract

Designing asphalt mixtures for pavement construction by controlling the moisture-mediated damage remains challenging. With the progression of time, this type of damage can accelerate deterioration via fatigue cracking and rutting unless inhibited. In this study, two types of hot asphalt mixtures (HAMs) were made by incorporating recycled concrete aggregates (RCAs), which were reinforced with rock wool fibers (RWFs). The first specimen was a normal mixture with a completely virgin aggregate, and the second one was a sustainable mixture with 30% RCAs. The proposed mixes were thoroughly characterized to assess the impact of RWF incorporation at various contents (0.5, 1, 1.5, and 2%) on moisture resistance. The optimal asphalt concentration (OAC) and volumetric parameters of the mixes were determined using the Marshall technique. The moisture susceptibility of the obtained HAMs was evaluated in terms of the tensile strength ratio (TSR). The results revealed that the moisture resistance, Marshall stability, flow, and volumetric parameters of the HAMs were improved due to the reinforcement by RWFs, indicating a reduction in the moisture sensitivity and an increase in TSR%. In addition, the HAMs designed with 1.5% RWFs displayed the highest TSR% (11.37) and Marshall stability compared to the control mix. The observed improvement in the moisture resistance and Marshall attributes of the prepared HAMs was ascribed to the uniform distribution of the RWFs that caused a well-interconnected structure and tightening in the asphalt concrete matrix. It is asserted that the proposed HAMs can be nominated for the construction of durable high-performance pavements.

Effect of Basalt Fiber Diameter on the Properties of Asphalt Mastic and Asphalt Mixture

“…At the same temperature, the phase angle of basalt fiber asphalt mastic was smaller than that of asphalt mastic without fiber. Compared to the asphalt mastic, the phase angle of the fiber asphalt mastic dropped by 4.8 • and 3.2 • , respectively, after adding 16 µm and 25 µm basalt fiber, according to the phase angle data at 76 • C. Because the fibers are covered with one another to shape a "bracket" and assumed to be part of a "network" in the asphalt mastic [38,39], a structural asphalt interfacial layer with a strong adhesion force formed on the fiber's surface after the asphalt made contact with it, improving the bonding performance of asphalt while also limiting the mastic's ability to deform around the fiber and lowering its fluidity [20]. Larger specific surface area fibers can absorb more asphalt and exhibit greater elastic properties.…”

“…Because of the larger specific surface area of 16 µm basalt fiber and the higher amount of monofilament fibers under the same fiber content compared to 25 µm basalt fiber, the adsorption capacity of fibers was proportional to their surface area, so fibers with a larger specific surface area can adsorb more asphalt, and fibers with smaller diameters in asphalt mastic showed better elasticity effects. Asphalt mastic had a three-dimensional network structure made of layers of evenly spaced-out fibers [38,39]. After the asphalt and fiber made contact, a layer of asphalt with a strong adhesion force formed on the fiber's surface, improving the bonding performance between asphalt and fiber and preventing the asphalt mastic from deforming around the fiber monofilament [20].…”

Evaluating the Moisture Susceptibility of Asphalt Mixtures Containing RCA and Modified by Waste Alumina

“…Huseen et al assessed the moisture damage to RCA-containing mixtures reinforced with rock wool fibers. The suggested HAM, according to the findings, is an appropriate option for pavement construction in hot climates [17,18]. Kavussi et al [19] examined the way RCA affected the mechanical characteristics of asphalt mixes.…”