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This paper investigates the preparation and properties of high-strength artificial blocks made from dredged silt with a clay content of 52.0%. A comparative analysis of the mechanical properties of dredged silt blocks produced using semi-dry pressing and vibration molding methods was conducted. The study examined the effects of using fly ash (FA) and ground granulated blast-furnace slag (GGBS) as substitutes for cement on the compressive strength, splitting tensile strength, and dry shrinkage of the blocks. Additionally, the microstructure of the dredged silt blocks was analyzed using scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and thermogravimetric analysis. The results show that specimens prepared using the pressing method exhibit better mechanical performance with compressive and splitting tensile strength reaching 64.8 MPa and 5.6 MPa at 28 d, respectively, which increased by 111.07% and 143.48% compared to specimens prepared through vibration molding. The addition of FA and GGBS reduces the early strength of the block to a certain extent but without a significant adverse effect on later strength. GGBS demonstrates faster hydration and a better filling effect. The addition of GGBS or FA refines the pore structure and reduces the diameter of pores in the paste, which is beneficial for improving the dry shrinkage performance of the block. At 120 d, the dry shrinkage of blocks containing 50% FA and GGBS shows a reduction of 29.7% and 27.1%, respectively, compared to blocks made with cement. The properties of the silt blocks can be notably enhanced through mechanical force, particle gradation, and hydration action. The preparation of artificial blocks such as road bricks and ballast blocks using dredged soil as the main raw material has been applied in projects such as the Yangtze River waterway regulation in China and Skikda Port in Algeria. [ABSTRACT FROM AUTHOR]

As natural aggregates become increasingly scarce, attention has turned to ultra-fine dredged sand (UDS) generated in waterway regulation engineering. UDS is typically challenging to utilize due to its high clay content and high water demand. This article uses ground granulated blast-furnace slag (GGBS)-based geopolymer to solidify UDS, along with sodium silicate (SS) and sodium hydroxide (SH) as alkaline activators. This paper explores the effects of SS modulus (SiO2/Na2O molar ratio) and mass percentage content of Na2O on the fluidity, setting time, mechanical properties, and shrinkage behavior of hybrid UDS-GGBS geopolymer (HUGG) paste. According to the research findings, increased SS modulus and Na2O content lead to decreased fluidity and setting time. When the Na2O content reaches 6%, flash coagulation occurs in the slurry, leading to more internal shrinkage cracks and pores. This has been confirmed by scanning electron microscope (SEM) analysis. When Na2O content is 5%, and SS modulus is 1.0, the 90-day maximum compressive strength reaches 56.53 MPa, corresponding to a splitting tensile strength of 6.83 MPa, which can be considered the optimal formulation. Meanwhile, basalt and polypropylene fibers (BF and PPF) are chosen to compensate for the susceptibility to drying shrinkage. Both BF and PPF can significantly inhibit the linear drying shrinkage of the HUGG paste. The BF's ability to enhance mechanical properties is more robust than PPF's, which can make the paste more homogeneous. The research contributes an effective method for the resource utilization of UDS. [ABSTRACT FROM AUTHOR]

In this study, the researchers aimed to broaden the applications of unsaturated polyester resin (UPR) composites in the building field by incorporating surface-modified titanium dioxide (TiO2) nanoparticles and reinforced chopped glass fibers within the UPR matrix. Specifically, the composites containing 4 wt.% TiO2 nanoparticles and 30 wt.% chopped glass fiber exhibited remarkable properties of 46.1 kJ/m2 in impact strength, 90.1 MPa in flexural strength, 78.8 MPa in tensile strength, and 121.5 °C in heat deflection temperature, which improve 207.5%, 80.3%, 62.5%, and 73.6%, respectively, when compared with the blank sample. Furthermore, the results of the corrosion resistance test showed that the composites performed poorly against polar organic and alkaline solutions, presented good corrosion resistance against acidic media, and behaved relatively stable in the salt solution. [ABSTRACT FROM AUTHOR]

The compressive, splitting tensile and immersion strength, drying shrinkage and microstructure of the cementing material made with waste silty clay soil from waterway regulation engineering were investigated in this paper. Cement (11.0–24.0 wt.%), fly ash (4.6–9.2 wt.%) and gypsum (1.9–3.8 wt.%) at different proportions were used in the mixtures. Results show that the specimen addition of appropriate cement, fly ash and gypsum presents excellent mechanical properties and water resistance and low drying shrinkage. The microstructure observation indicates that there are quite a lot of hydrate products in matrix which verifies the formation of cementing compounds. The results obtained suggest that there is potential to manufacture cementing material with silty clay soil in substitution of ordinary concrete to use in hydraulic engineering. [ABSTRACT FROM AUTHOR]