Key Engineering Materials Vol. 998

Abstract: The limitations of river water resources and river sand have driven the development of concrete that uses sea sand and seawater as alternative raw materials. The use of concrete with sea sand and seawater has been the focus of previous research to enhance the properties and strength of the concrete. In this study, natural zeolite powder, which is a natural material containing high silica (SiO₂) and alumina (Al₂O₃), was utilized. The finely ground zeolite powder was added to the concrete mix with three variations: 5%, 7.5%, and 10% from weight of cement. The main objective of this research is to evaluate the mechanical properties of concrete using sea sand and seawater at the age of 14 and 56 days, comparing it with concrete using river sand and river water. Test results show a significant increase in compressive strength of concrete with the addition of zeolite powder, especially at the 7.5% concentration, compared to zeolite-free concrete. Although a decrease in compressive strength occurred at 56 days compared to 14 days, this decrease did not exceed the compressive strength value of zeolite-free concrete. Additionally, in the split tensile strength test of concrete, the results show positive development, with an increase in the split tensile strength value at 56 days, especially at the zeolite concentrations of 7.5% and 10%, compared to 14 days. This indicates that the addition of zeolite can enhance the concrete's ability to resist tensile forces, making it suitable for structures requiring high tensile strength.

Abstract: In the comparative study of single mixed PVA fiber (0,1%, 2%, 3%) and basalt fiber (0,0.1%, 0.2%, 0.3%) on the polymer mortar fluidity and mechanical properties, the results show that: PVA fiber and basalt fiber under the appropriate amount can improve mortar water retention, basically will not appear water phenomenon, which makes the construction more convenient. When the basalt and PVA fibers were 0.2%, the 28-d folding resistance was 5.60 MPa and 5.72 MPa, respectively. The results of the compressive strength test showed the same pattern as the folding strength. When the amount of PVA and basalt fiber was 0.2%, the 28-d folding strength was the greatest, which is 44.91 MPa and 41.92 MPa, respectively.

Abstract: Magnesium phosphate cement concrete (MPCC) has high early strength, which is conducive to achieving rapid repair of winter concrete pavements under no-maintenance conditions. In this paper, we investigated the influence mechanism of four cement antifreeze components on the mechanical and durability properties of MPCC under the severe cold environment, focusing on the development law of the performance of MPCC as a rapid repair material for pavements. The results show that the antifreeze effect of MPCC antifreeze components under severe cold environments is contrasted as MgCl₂ > Mg (NO₃)₂ > Ethylene glycol > Mg (NO₂) ₂. However, the addition of antifreeze components, especially inorganic salt antifreeze components, will also have an adverse effect on the antifreeze resistance of concrete during the service period.

Abstract: PVA fiber reinforced toughness-concrete is widely used in masonry structure reinforcement due to its cost-effectiveness and excellent toughening effects. The tensile strength of the material significantly impacts the shear capacity of the masonry. This study systematically investigates the effects of fiber length and dosage on the uniaxial tensile behavior of PVA fiber reinforced toughness-concrete through finite element simulation and axial tensile tests. Additionally, the specific influence of fiber inclusion on the material’s tensile strength was analyzed through experiments and fitting calculations. The results indicate that optimizing the length and dosage of fibers can significantly enhance the tensile performance of the toughness-concrete. Consequently, this research has optimized the mix proportion of the toughness-concrete, thus balancing reinforcement effectiveness with material cost optimization. These achievements not only enhance the structural safety and durability of the reinforced masonry but also have significant practical implications for improving the shear carrying capacity of masonry structures.

Abstract: With the acceleration of urbanization and the expansion of densely populated areas, the safety and durability of building structures in metropolitan areas have become increasingly significant issues. This trend has raised the requirements for building materials, particularly in the production of prefabricated building components, where the use of high-strength, high-toughness concrete has become the norm. Using high-toughness concrete reinforced with organic fibers can enhance the mechanical properties of concrete while ensuring good workability, and POM fibers are among the most widely used organic fibers. This study primarily investigates the mechanical properties of prefabricated hollow wall panels made from high-toughness concrete reinforced with POM (polyoxymethylene) fibers. The mechanical behavior of POM fiber-reinforced concrete was analyzed through laboratory tests, including assessments of compressive and tensile properties. The results indicate that the inclusion of POM fibers significantly improves the maximum elastic compressive strength and ultimate compressive strength of the concrete, as well as enhancing its tensile capabilities. Using the CDP model theory in finite element analysis, this study further calculated the structural response of high-toughness concrete prefabricated hollow wall panels under wind and seismic loads, demonstrating their practical feasibility in engineering applications. This research not only provides a scientific basis for the application of POM fiber-reinforced high-toughness concrete but also offers new directions for future research and application in building materials, particularly in urban constructions requiring high safety and durability.