Shu Liu

The utilisation of excavated soil with high moisture and high viscosity faces challenges such as complex dehydration processes and difficult material dispersion. Controlled Low-Strength Material (CLSM) provides a feasible pathway for its dehydration-free resource utilisation. To enhance sustainability, alkali-activated materials can replace Portland cement as the binder in CLSM. However, the influences of activator concentration on CLSM performance remain unclear, and the dispersibility of high-viscosity soil needs further improvement. Therefore, this study develops a novel CLSM using high-viscosity excavated soil and alkali-activated slag, with coal bottom ash (CBA) introduced to improve its dispersibility. Through flowability, setting time, and compressive strength tests, the influences of binder content, alkaline dosage, silicate modulus, soil-to-aggregate ratio, and wet-dry cycles on CLSM performance are systematically investigated, followed by hydration heat and thermogravimetric analyses to reveal the underlying mechanisms. The results demonstrate that increasing the binder content promotes hydration and enhances the mechanical properties of CLSM. CBA can effectively improve flowability but has limited effects on hydration and strength enhancement. Increasing the alkaline dosage accelerates early hydration and increases 7-day compressive strength but may retard later-stage strength development. Reducing the silicate modulus is beneficial to early hydration and performance, whereas a high modulus presents higher later-stage compressive strength. Wet-dry cycles exert dual effects on CLSM through promoting hydration and inducing internal crack propagation, ultimately resulting in strength degradation under wet-dry cycles. This paper provides a theoretical basis and technical reference for the efficient and low-carbon resource utilisation of high-viscosity excavated soil as filling material.

To address the technical bottlenecks associated with the poor overall performance of emulsified asphalt mixtures incorporating high‐proportion (84 wt%) recycled asphalt pavement (RAP) aggregates, this study proposes a synergistic modification strategy using styrene‐butadiene rubber (SBR) and nano‐silica (SiO ₂ ), coupled with the regulation of cement and polyester fiber contents. Through systematic rheological characterization and performance testing, the results demonstrate that SBR/SiO ₂ modification is able to enhance the high‐temperature properties of the emulsified asphalt binder, as evidenced by a reduced penetration, a lower phase angle, and an increased complex modulus. Meanwhile, this modification also slightly affects the low‐temperature performance of the asphalt binder by boosting its ductility and reducing its creep stiffness (S); however, the m ‐value was decreased. Fourier transform infrared spectroscopy (FTIR) results demonstrate that the synergistic effect between SBR and SiO ₂ is physical in nature. The optimal formulation for the asphalt mixtures was ultimately determined as follows: 3.9% binder modified by 3.5 wt% SBR and 3 wt% nano‐SiO ₂ , 1.5 wt% cement, and 0.3 wt% polyester fiber, achieving a splitting strength of 0.82 MPa, a dynamic stability of 4683 times/mm, a flexural strain of 2526 με, and a freeze–thaw splitting ratio of 83.3%. This research establishes a basis for the high‐value utilization of RAP aggregates in emulsified asphalt mixtures and contributes to the advancement of low‐carbon, sustainable pavement materials.

Usual-temperature synthetic pitch (USP) is a modifier that can efficiently reduce the mixing temperature and improve the overall engineering properties of warm-mix asphalts; however, few studies are reported for its application in cold patch asphalt. In this article, cutback asphalts were prepared with USP, bitumen, biodiesel, an antistripping agent, and a tackifier. Referring to a series of single-factor analyses on the cutback asphalt viscosity, the reasonable dosage ranges for the USP, antistripping agent, and tackifier were first determined. Based on these, a four-factor and four-level orthogonal test plan was proposed to guide the selection of some potential appropriate mix design schemes. The recommended mix design schemes were then screened out by successively examining the physical properties, adhesion, workability, Marshall stability, high- and low-temperature rheological properties, and compatibility. Two design schemes with mass proportions of 6:18:0.3:6 (Scheme 1) and 6:20:0.4:2 (Scheme 2) for USP, diluent, antistripping agent, and tackifier, respectively, were finally selected. The engineering properties of the prepared specimens meet the standard requirements. Compared with Scheme 1, Scheme 2 presents better Marshall stability and high- and low-temperature performance. The proposed mix design schemes can guide the preparation of USP-modified cold patch asphalts and promote their application in practice.

Zeolite-Foamed Asphalt (ZFA), as a typical-used Warm Mix Asphalt (WMA) in practice, has significant advantages in environmental friendliness and construction convenience, but its moisture susceptibility is relatively weak. Most of the existing research regarding its moisture susceptibility was carried out by performing macroscopic tests, which are incapable of providing theoretical bases for moisture susceptibility optimization. This article studies the moisture susceptibility of ZFA from a mesoscopic perspective based on Surface Free Energy (SFE) concept. To determine the SFE of each composition, sessile drop tests were first conducted on three types of aggregates and three types of bitumen binder, considering different zeolite incorporation contents. Several SFE-based factors, including cohesion of the binder, dry work of adhesion, work of debonding, Spreading Coefficient (SC) and energy ratio (EP1), were calculated. These factors were also correlated with the mass loss ratio obtained through water-boiling stripping tests to validate their feasibility in evaluating the moisture susceptibility of ZFA. The results indicate that the increase of the polar component and the decrease of the dispersion component of the binder’s SFE resulting from the zeolite foaming process affect the moisture susceptibility of the ZFA. The influence could be either positive or negative, depending on the dominated failure mode and the aggregate”s SFE. An aggregate with a higher polar component of the SFE is more recommended when an interfacial adhesion failure occurs. Dry work of adhesion and EP1 demonstrate good correlations with the mass loss ratios and the correlation coefficients are not lower than 0.8057. The results can theoretically guide the optimization of the moisture susceptibility of ZFA in practice.

In this work, a new preparation method is developed for the preparation of Ce/Ni-ZrO2 nano-catalyst (Ce/Ni-ZrO2-N). Although scholars have studied similar catalytic systems, there is still room for improvement in terms of nickel surface area, catalytic efficiency, and mechanism analysis. The Ce/Ni-ZrO2-N exhibits a large nickel surface area (50.6 m2∙g-1) and a small nickel particle size (~5.1 nm), which uses UiO-66 not only as a precursor for the preparation of ZrO2 with a large surface area, but also as a dispersant for the confinement of nickel nanoparticles. The catalyst demonstrated excellent catalytic performance at high GHSVs. With a 16-fold increase in GHSVs, the CO2 conversion of Ce/Ni-ZrO2-N decreased by only 32.1%, while that of the control group is 50.3%. This is attributed to the high nickel surface area and relatively low activation energy. Moreover, the characterization and Density Functional Theory (DFT) studies revealed that electron transfer from Ce to Ni enhances the activation of CO2 on the Ni sites, which subsequently contributes to a better catalytic performance. In addition, the catalyst showed excellent anti-coking ability during the 40 h's testing, which, according to DFT calculations, is attributed to the high energy barrier for coke formation on the active sites.

For small scale off-grid wind-solar-diesel hybrid generations with energy storage (WHGES), it is necessary to coordinate the operation of generation units and energy storage unit to maintain the voltage constant and supply the loads. This paper proposes a low cost charging scheme for off-grid WHEGES with 48V DC bus voltage. It is possible to realize the dynamic charging control of the storage unit without bidirectional converter, and a reasonable charging curve is achieved by controlling diesel generator. The scheme proposed in this paper can not only reduce hardware cost but also improve reliability of the system. Finally, a model of off-grid WHGES was built employing MATLAB/SIMULINK, the control strategy proposed in this paper is verified.