In order to reduce the manufacturing cost of foamed ceramics and expand the application scope of industrial solid waste, in this study, a new type of environment-friendly foamed ceramics was prepared using direct high-temperature foaming with waste silicomanganese slag (SMS) and fly ash (FA) as raw materials and silicon carbide (SiC) as a foaming agent. The influence of SMS content, SiC content, and sintering temperature on the characteristics and microstructure of the specimen were explored. More concretely, the compressive strength, pore morphology, bulk density, and crystalline composition of the foamed ceramics were discussed. The foaming mechanism was also further analyzed. The results showed that including 20% SMS significantly reduced the melt’s viscosity and stimulated bubble expansion. This, in turn, facilitated the creation of a porous structure. Moreover, it was noted that samples containing 20% SMS exhibited an anorthite phase when sintered at 1110 °C, resulting in enhanced compressive strength. The bulk density and compressive strength of the foamed ceramics decreased with an increase in the sintering temperature and SiC content. This trend was primarily attributed to the higher total porosity and the insufficient support of the pore wall to the matrix. The best all-around performance was achieved with 20 wt% SMS, 80 wt% FA as raw material, SiC addition of 1.0 wt%, and a sintering temperature of 1100 °C. Under these conditions, the compressive strength, bulk density, and total porosity of the foamed ceramics were 8.09 MPa, 0.57 g/cm³, and 71.04%, respectively. Taken together, the outstanding porous structure and mechanical properties of this foamed ceramic make it suitable for use as insulation or for building partition materials.

In order to investigate the effect of high-performance polypropylene (HPP) fiber on the impact resistance of recycled aggregate concrete (RAC), the impact resistance of HPP fiber-reinforced RAC (HFRAC) was investigated using drop-weight impact equipment and compared with steel fiber-reinforced recycled aggregate concrete (SFRAC). The effects of recycled aggregate replacement rates, fiber content, and fiber type were analyzed. Furthermore, the log-normal distribution and two-parameter Weibull distribution statistical methods were used to fit the probability distribution and predict the failure probability of the initial and final crack impact resistance of HFRAC and SFRAC specimens. The experimental results showed that the impact resistance of RAC decreased with the increase in recycled aggregate replacement rates. HPP fiber had little effect on the impact resistance of initial cracking in RAC, but significantly improved the impact resistance of final cracking in RAC, while steel fiber significantly improved the impact resistance of initial cracking in RAC, but had little effect on the impact resistance of final cracking in RAC. The anti-impact energy consumption and ductility of RAC increased with the increase in HPP content. When the HPP fiber content was 1.25% and the recycled aggregate replacement rate was 50%, the maximum impact energy consumption of RAC was 114.5 times higher than that of the plain RAC concrete specimen, and the maximum ductility ratio of the RAC matrix was 118.3. The addition of HPP fibers significantly improved the impact resistance of RAC. The fitting results showed that the distribution characteristics of HFRAC and SFRAC impact resistance were represented by a log-normal distribution and two-parameter Weibull distribution, with the former presenting a better fit to predict the impact resistance of HFRAC and SFRAC.

As the threat of explosion incidents continues to intensify, it poses a significant risk to human safety. This study proposes a variable stiffness re-entrant (VSRE) core sandwich panels with negative Poisson’s ratio to enhance the explosion protection effect. Numerical simulation methods are used to analyze the impact of explosion loads on the structure, and the model is verified using the experimental results from existing studies. The VSRE core demonstrates excellent explosion protection performance. Compared with the traditional re-entrant (RE) core of equivalent mass, in the numerical simulation, the lower plate maximum displacement ( maxD ) is reduced by 11.85%, while the energy absorption ( EA ) of the system is increased by 14.39%. The variable stiffness factor of this design enables the control of density deformation, thereby achieving adjustable energy absorption capacity. The parameter study of the system shows that through the reasonable combination of core thickness, side distance, and gradient configuration, the best performance can be achieved. Specifically, combining the VSRE core with a thicker rear plate can more effectively distribute stress and material flow, reducing the peak deformation by up to 81.11%. This structure enables more efficient material flow towards the deformation center, effectively reducing the overall deformation and improving the energy absorption capacity. Therefore, the application of this variable stiffness helical plate in explosion protection systems has great potential.