4. EXPERIMENTAL INVESTIGATION 4.1 Materials and Mix Designs The experimental investigation was carried out using chemical grouting systems for rock masses, aimed at sealing discontinuities, reducing residual permeability, and consolidating fractured zones. Three technological families were evaluated, each with different gelation mechanisms and rheological behavior: acrylamide-based resins, acrylate-based resins, and mineral colloidal silica systems. a. The acrylamide-based system corresponds to a two-component formulation that gels through free-radical polymerization in an aqueous medium. Part A consists of the acrylamide base solution and an amine activator (mainly triethanolamine, TEA), while Part B contains an oxidizing initiator based on sodium or ammonium persulfate, previously dissolved in water. Reaction kinetics were controlled through the incorporation of a potassium ferricyanide (KFE)–based retarder, allowing adjustment of the gel time to the required injection conditions. b. The acrylate-based resins evaluated are also two-component polymeric systems, designed for low-viscosity, high-penetrability grouting applications. Part A consists of the acrylic monomer in aqueous solution with an amine activator (TEA), while Part B incorporates a persulfate-based oxidizing initiator. Gel time control was achieved by dosing KFE retarder, reaching gel times compatible with long-reach, low-pressure injection. c. Colloidal silica systems are based on a stable aqueous suspension of nanometric amorphous silica particles, which gels through physicochemical particle aggregation. Gelation was modulated by the addition of a sodium chloride (NaCl) activating solution, with typical concentrations between 10% and 20% by weight relative to the mixing water, used either in granular form or as an aqueous solution, depending on the formulation. For each material family, specific experimental formulations were developed, mainly varying the dosage of retarders or activators in order to evaluate their influence on gelation kinetics and system stability. Details of the tested mix designs are presented in Tables 1 and 2. Table 1 – Formulations of the Acrylamide- and Acrylate-Based Polymeric Systems Evaluated Evaluated system Design No. Theoretical Density (g/cm³) Part A Parte B Volume (ml) Base (g) Water (g) TEA (g) Retarder (g) Persulfate (g) Water (g) Acrylamide system 1 1.02 9.99 40.11 1.10 0.57 1.10 49.45 100.0 2 1.02 9.99 40.11 1.10 0.76 1.10 49.45 100.0 Acrylate system A 1 1.06 53.92 54.01 2.20 1.28 2.20 98.89 200.0 2 1.06 53.92 54.01 2.20 1.44 2.20 98.89 340.0 Acrylate system B 1 1.11 200.00 - 5.00 0.60 10.00 159.12 340.0 2 1.11 200.00 - 5.00 0.80 10.00 159.12 340.0 3 1.11 200.00 - 5.00 1.00 10.00 159.12 340.0 1 1.11 300.00 - 8.30 3.00 6.00 300.00 600.0
RkJQdWJsaXNoZXIy MTM0Mzk2