RESUMEN
Polycarboxylate superplasticizers BMC-L and BMC-S were utilized as modifiers in the formulation of novel cement-based grouting materials. Indoor tests were conducted on 32 groups of cement slurries, varying by water-cement ratio (0.5:1 and 0.6:1) and modifier content (0, 2‱, 4‱, 6‱, 8‱, 10‱, 12‱, and 14‱), to test their density, funnel viscosity, water separation rate, and stone rate. Four groups of slurry modified with BMC-L were selected as the preferred slurry, and the apparent viscosity test, uniaxial, and triaxial compression test of the slurry stone body were conducted. The study investigated the influence of BMC-L on various properties of the slurry, including its apparent viscosity, uniaxial compressive strength, stress-strain relationships, shear strength parameters, and elastic modulus. Ultimately, the pore structure and phase composition of the slurry stone body were detected by Nuclear Magnetic Resonance (NMR) and X-ray Diffraction (XRD), and the impact of BMC-L on slurry performance was examined from a microstructural perspective. Results indicate that the two polycarboxylate superplasticizers exert minimal influence on the density and water separation rate of the slurry. Within the effective incorporation range of the polycarboxylate superplasticizer, increasing the dosage correlates with a decrease in both the stone rate and viscosity of the slurry. BMC-L significantly enhances the mechanical properties of the slurry stone body by promoting more complete cement hydration and reducing porosity. The uniaxial compressive strength of slurry stone body with a 6 ‱ BMC-L dosage reached 29.7 MPa after 7 days and 38.5 MPa after 28 days of curing, representing increases of 118.4% and 64%, respectively, compared to masonry with 0 BMC-L dosage. The shear strength parameters and elastic modulus of the slurry stone body also showed corresponding increases.
RESUMEN
As a widely used material in underground engineering, clay-cement slurry grouting is characterized by poor initial anti-seepage and filtration capacity, low strength of the resulting stone body, and a tendency to brittle failure. In this study, a novel type of clay-cement slurry was developed by adding of graphene oxide (GO) as a modifier to ordinary clay-cement slurry. The rheological properties of the improved slurry were studied through laboratory tests, and the effects of varying amounts of GO on the slurry's viscosity, stability, plastic strength, and stone body mechanical properties were analyzed. The results indicated that the viscosity of clay-cement slurry increases by a maximum of 163% with 0.05% GO, resulting in a decrease in the slurry's fluidity. The stability and plastic strength of GO-modified clay-cement slurry were significantly enhanced, with the plastic strength increasing by a 5.62 time with 0.03% GO and a 7.11 time with 0.05% GO at the same curing time. The stone body of the slurry exhibited increased uniaxial compressive strength and shear strength, with maximum increases of 23.94% and 25.27% with 0.05% GO, respectively, indicating a significant optimization effect on the slurry's durability. The micro-mechanism for the effect of GO on the properties of slurry was investigated using scanning electron microscopy (SEM) and a diffraction of X-rays (XRD) test. Moreover, a growth model of the stone body of GO-modified clay-cement slurry was proposed. The results showed that after the GO-modified clay-cement slurry was solidified, a clay-cement agglomerate space skeleton with GO monolayer as the core was formed inside the stone body, and with an increase in GO content from 0.03% to 0.05%, the number of clay particles increased. The clay particles filled the skeleton to form a slurry system architecture, which is the primary reason for the superior performance of GO-modified clay-cement slurry when compared with traditional clay-cement slurry.