The proper reutilization of the phosphogypsum (PG) by-product derived from the production of phosphoric acid and recycled concrete aggregate (RCA) from waste concrete in roadbase materials is of great necessity and importance. This investigation tried seeking a new approach to reuse them to high quality, including turning PG into calcinated PG (CPG) via washing and calcination, as well as adopting sodium metasilicate nonahydrate (SMN) to strengthen the roadbase materials of cement-stabilized CPG and RCA. Upon the mix design, with a series of experiments including unconfined compressive strength, the wet–dry cycle, freeze–thaw cycle, and scanning electron microscopy, the comprehensive effects of PG treatment, the CPG to RCA mix ratio, SMN dosage, wet–dry cycle and freeze–thaw cycle on the road performance of roadbase materials were well evaluated, and the traffic bearing capacity and microstructure characteristics were also analyzed. The results demonstrate that the 7 d unconfined compressive strength of CPG/RCA roadbase materials can reach 5.34 MPa as the CPG and SMN dosage are 20% and 11%, respectively, which meets the requirements of an extremely and very heavy traffic grade. After five wet–dry cycles and freeze–thaw cycles, the resistance of the CPG/RCA roadbase materials to moisture and frost was significantly improved as 11% SMN was added. Meanwhile, SMN contributes to the reduction in crack width and densifies the microstructure of CPG/RCA roadbase materials. The research results can be used to provide new guidance for building more durable roadbase materials.

Waste poly(ethylene terephthalate) (PET) drinking bottles and end-of-life scrap rubber tires are common municipal solid wastes discarded and produced every day, which are usually disposed of in landfills and stockpiles, occupying a great quantity of land and causing serious environmental issues. This study aims to first turn waste PET into two value-added derived additives under the chemical treatment of two amines, namely triethylenetetramine (TETA) and ethanolamine (EA), respectively, and then adopt them in association with crumb rubber (CR) to modify virgin bitumen for preparing various rubberized asphalt mixtures. Subsequently, the high- and low-temperature properties of the rubberized binder modified by PET additives (PET-TETA and PET-EA) were comparatively characterized through dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests, while the rutting resistance, fatigue resistance, and dynamic modulus of the further fabricated mixtures were evaluated and validated through mixture tests. The results obtained indicate that 2 wt.% PET-TETA and PET-EA contribute to increase the rutting failure temperature of asphalt rubber from 82.2 °C to 85.5 °C and 84.2 °C, respectively, retaining the high grade of PG 82; the low-temperature grade of asphalt rubber slightly decreased from PG-28 to PG-22 as the additive was added; the rut depth slightly changed from 3.10 mm to nearly 3.70 mm; and PET-TETA exhibits the potential to be capable of extending the fatigue life of asphalt rubber in contrast with PET-EA at different stress levels within 450 kPa. Based on the findings of this study, the developed recycling approach is considered to be applicable to not only alleviate the environmental concerns caused by the landfills and stockpiles of those wastes but also make them valuable for building more durable pavement.

In this study, waste concrete fine aggregates and cement are applied to sludge solidification and resource recycling. The unconfined compressive strength (UCS) test is performed to investigate the variation in the strength and stress–strain properties of the solidified sludge with the content and particle size of waste concrete fine aggregate, cement content, and curing time. The results show that incorporating waste concrete fine aggregates can improve the UCS of cement-solidified sludge, which can achieve the optimum effect when the fine aggregate content ranges from 12% to 15%. However, compared with the fine aggregate content, the cement content and curing time are the main factors in improving the strength of waste concrete fine aggregate and cement-solidified sludge (WCSS). The stress–strain curves of WCSS comprise four stages. The failure strain ε_f of WCSS with four fine aggregate contents decreases in a power function with the increase in q_u, and ε_f is mostly distributed when the content is 1.1–2.1%. A linear relationship is observed between E₅₀ and q_u. This study attempts to promote the recycling of waste concrete fine aggregates and obtain solidified sludge with excellent mechanical properties, providing some reference for practical engineering applications.

The total ultimate resistance (or bearing capacity) of driven piles considering setup effects is composed of initial ultimate resistance and setup resistance, and the setup effects of driven piles are mainly reflected by the setup resistance. In literature, a logarithmic empirical formula is generally used to quantify the setup effects of driven piles. This paper proposes an increase factor (M_setup) to modify the resistance factor and factor of safety calculation formula in accordance with the load and resistance factor design (LFRD) principle; here, the increase factor is defined as the ratio of the setup resistance (R_setup) to the initial ultimate resistance (R₀) of driven piles. Meanwhile, the correlation between R₀ and R_setup is fully considered in the resistance factor and factor of safety calculation. Finally, the influence of four key parameters (ratio of dead load to live load ρ = Q_D/Q_L, target reliability index β_T, M_setup, correlation coefficient between R₀ and R_setup, ρ_R0,Rsetup) on the resistance factor and factor of safety are analyzed. Parametric research shows that ρ has basically no effect on the resistance factor, which can be taken as a constant in further research, and ρ has a significant influence on the factor of safety. The value of M_setup has almost no effect on the resistance factor and factor of safety. However, β_T and ρ_R0,Rsetup have a significant influence on the resistance factor and factor of safety, so the value selection of β_T and ρ_R0,Rsetup are crucial for reliability-based design of driven piles. Through this study, it is concluded that considering setup effects in reliability-based design of driven piles will greatly improve the prediction for design capacity.

Potential damage caused by earthquakes combined with reduced comfort due to traffic has become a big challenge when designing modern buildings, and base-isolation is one of the most effective solutions to such a problem. However, most isolation bearings cannot provide sufficient mitigation for both earthquakes and traffic-induced vibrations simultaneously. To this end, this research proposes a new type of three-dimensional isolation bearing for the mitigation of both earthquake effects and traffic-induced vibrations, which is composited by a thick rubber bearing, an auto-reset flat sliding bearing, and a double concave friction pendulum bearing. In this study, the analytical hysteresis model of the proposed isolation bearing was derived and experimentally validated. In addition, the fatigue performance and vertical compression performance of the proposed isolation bearing was tested and analyzed. Finally, the mitigation effect for traffic-induced vibrations of the proposed isolation bearing was validated through a field test.