330 Table 2 – Formulations of the Evaluated Colloidal Silica Systems Evaluated system Design No. Theoretical Density (g/cm³) Base colloidal (g) NaCL Volume (ml) % (g) Colloidal system A 1 1.09 1647.00 11.11 176.11 1667.0 2 1.09 1647.00 12.50 198.14 1687.0 3 1.09 1647.00 14.30 226.67 1714.0 Colloidal system B 1 1.18 1800.00 11.11 176.11 1667.0 2 1.18 1800.00 12.50 198.14 1687.0 3 1.18 1800.00 14.30 226.67 1714.0 4.2. Methodology The experimental methodology was designed to characterize the rheological, physical, and kinetic behavior of the evaluated grouting systems, ensuring result repeatability and representativeness with respect to real field conditions. Tests were conducted in accordance with recognized international standards, as well as technical procedures recommended by the chemical supplier. • Control of rheological and physical properties The dynamic viscosity of the mixtures was determined using an immersion cup, in accordance with ASTM D4212, by recording the flow time in seconds and subsequently converting it to centipoise (cP) based on the correlations established in the standard. The governing equation is shown below: V = K (t – c) Where: V = kinematic viscosity, cSt (mm²/s); 1 cSt ≈ 1 cP t = efflux time, s ;,W = constants established in the standard depending on the cup number used (for Cup No. 1, ; = 1.1 and c=29) Measurements were performed immediately after mixing and repeated periodically during the material workability phase, in order to assess rheological stability prior to gelation. Grout density was measured in accordance with ASTM D4380, using a calibrated mud balance. • Evaluation of gel time Gel time was determined using the cup test method, following the guidelines of ASTM D2471 and CIRIA C774. Tests were initiated between 20 and 45 minutes after mixing, depending on the formulation evaluated, and continued until the complete transition of the system from the liquid state to the gelled state. The gelation criterion was established based on visual and tactile assessment, in accordance with standardized procedures. • Thermal control The temperature of the components (base resin, activators, retarders, and saline solutions, as applicable) was measured prior to mixing using calibrated digital thermometers. Ambient temperature was also recorded during test execution. In all cases, it was verified that material temperatures remained below 32 °C, the limit established to prevent uncontrolled acceleration of the chemical reaction.
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