Jie Yang’s scientific contributions

Cement-based materials are essential in modern construction, valued for their versatility and performance. Rheological properties, including yield stress, plastic viscosity, and thixotropy, play indispensable roles in optimizing the workability, stability, and overall performance of cement composites. This review explores the effects of supplementary cementitious materials (SCMs), chemical admixtures, nanomaterials, and internal curing agents on modulating rheological properties. Specifically, SCMs, including fly ash (FA), ground granulated blast furnace slag (GGBFS), and silica fume (SF), generally improve the rheology of concrete while reducing the cement content and CO2 emissions. Regarding chemical admixtures, like superplasticizers (SPs), viscosity-modifying agents (VMAs), setting-time control agents, and superabsorbent polymers (SAPs), they further optimize flow and cohesion, addressing issues such as segregation and early-age shrinkage. Nanomaterials, including nano-silica (NS) and graphene oxide (GO), can enhance viscosity and mechanical properties at the microstructural level. By integrating these materials above, it can tailor concrete for specific applications, thereby improving both performance and sustainability. This review presents a comprehensive synthesis of recent literature, utilizing both qualitative and quantitative methods to assess the impacts of various additives on the rheological properties of cement-based materials. It underscores the pivotal roles of rheological properties in optimizing the workability, stability, and overall performance of cement composites. The review further explores the influences of SCMs, chemical admixtures, nanomaterials, and internal curing agents on rheological modulation. Through the strategic integration of these materials, it is possible to enhance both the performance and sustainability of cement composites, ultimately reducing carbon emissions and advancing the development of eco-friendly construction materials.

This study investigated the influence of microbead dosages (0, 5, 10, 15, and 20%) on the frost resistance of expanded polystyrene (EPS) concrete. Five groups of EPS concrete specimens were prepared and subjected to rapid freeze–thaw tests. The freeze–thaw deterioration of EPS concrete was assessed using macroscopic indicators, including mass loss, strength loss, and dynamic elastic modulus loss. The underlying deterioration mechanism was revealed through the analysis of the EPS particle–matrix interface. A concrete damage plasticity model of EPS concrete based on damage mechanics theory was established. The results indicate that the addition of microbeads increased the strength of EPS concrete by 38–53%, reduced the strength attenuation after freeze–thaw damage by 8.1%, and improved the frost resistance level by 10–60 grades. The optimal dosage of microbeads is 15% of the cementitious material. The interfacial transition zone gaps in EPS concrete with added microbeads after freeze–thaw cycles are smaller, contributing to a more complete hydration reaction. The freeze–thaw damage model established in this study accurately reflects the freeze–thaw damage law of EPS concrete and provides a reference for studying the mechanical properties of EPS concrete under freeze–thaw cycles. The research findings of this study can enhance the strength and service life of EPS concrete, expanding its application scope as a structural material. The study provides valuable insights for future research and engineering applications related to the frost resistance of EPS concrete.

Landfill gas generated by municipal solid waste (MSW) landfills is the world’s third largest source of greenhouse gas emissions. Additionally, the accumulation of landfill gas in waste piles can trigger instability in landfill piles. Based on the exponential distribution pattern of the variation of gas permeability coefficients with burial depth measured in situ, this paper presents an analytical solution for landfill gas-pressure distribution that is more in line with on-site conditions and has been verified by numerical calculations. Compared with cases where the gas permeability coefficient of landfill piles remains constant, the consideration that the gas permeability coefficient of MSW decreases exponentially with increasing burial depth is more likely to cause the accumulation of landfill gas at the landfill bottom, leading to higher gas pressure that can be more than five times higher than that in the former case. Based on a numerical analysis of gas extraction simulations, constant pressure gas extraction is relatively more effective in that a relative pressure of −0.1 kPa can lower the gas pressure in almost the entire pile, while bottom drainage fails to completely collect landfill gas even using a flux of 10–30 times ML.

In this study, the effect of microbead dosages (0%, 5%, 10%, 15%, and 20%) on the carbonation resistance of expanded polystyrene (EPS) concrete was investigated. Five groups of EPS concrete specimens were produced and underwent rapid carbonation testing. The carbonation depth and strength after carbonation of the specimens were measured at different carbonation ages (7 days, 14 days, and 28 days) and analyzed to determine the effect of microbead dosages and compressive strength on carbonation resistance. Results indicated that the carbonation depth increased with the progression of carbonation time. The introduction of microbeads was found to significantly improve the carbonation resistance of EPS concrete, leading to a reduction in carbonation depth of over 50% after 28 days and an increase in strength after carbonation by 18–56%. A relative compressive strength model for EPS concrete after carbonation was developed, which could accurately characterize the growth of compressive strength. Based on the analysis of EPS concrete carbonation depth data, a prediction model for the carbonation depth of EPS concrete with microbead dosage was established through fitting, providing improved accuracy in predicting carbonation resistance. The microstructure of EPS concrete was also examined using scanning electron microscopy to uncover the underlying mechanisms of microbead enhancement on carbonation resistance. These findings have potential implications for future research and engineering applications in the carbonation resistance of EPS concrete.