PSI - Issue 67

I. Flores-Vivián et al. / Procedia Structural Integrity 67 (2025) 80–89 Ismael Flores-Vivián / Structural Integrity Procedia 00 (2024) 000 – 000

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Table 3. Si/Al Ratio, Material Type and General Composition for NaY Zeolite Production

Si/Al

71/29

Type of material

Na 56 [Al 56 SiO 384 ] : 250H 2 O

Composition

4.62Na 2 O : Al 2 O 3 : 10SiO 2 : 180H 2 O

2.3.1. Seeding gel Seeding can alter the nucleation process by providing nuclei or active surfaces for the growth of the product. This gel was prepared 24 hours prior to the preparation of the next step, to allow the formation of nuclei. For the preparation of the seeding gel , 1.05 g of NaAlO 2 , 2.04 g of NaOH and 9.98 g of H 2 O were mixed in a polypropylene beaker, stirring until completely dissolved at a speed of 1500 rpm, for 5 minutes, with the help of a Silverson L4RT high-shear mixer. Subsequently, the Na 2 SiO 3 was added and continued to be stirred constantly until homogenized, for 10 minutes. 2.3.2. Feedstock gel For the preparation of the feedstock gel, 6.55 g of NaAlO 2 , 0.07 g of NaOH and 65.49 g of H 2 O were mixed, stirring until dissolved at a speed of 1500 rpm for 10 minutes. Finally, 71.22 g of Na 2 SiO 3 were incorporated while stirring for another 10 minutes, until a smooth gel was obtained. 2.3.3. Over all gel Once the seed gel was obtained, 8.25 g of it was slowly added to the feedstock gel. It was shaken at 1500 rpm for at least 20 minutes. After this step, the product was recovered. The product obtained was filtered and washed with H 2 O using a filtration flask and filter paper with an opening of 11μm. The washing was carried out until the pH of the material was reduced to approximately 10, which was determined with the help of test strips. Subsequently, the material was dried in a vacuum desiccator with thermostat at a temperature of 40°C for 24 hours. Finally, the material was pulverized using agate mortar. 2.4. Geopolymer Preparation Metakaolin-based geopolymer pastes were prepared with an AAS consisting of a combination of Na 2 SiO 3 and NaOH and H 2 O. Three types of pastes were prepared, one for reference, one with ZN zeolite replacement, and one with NaY zeolite replacement. Table 4 shows the parameters for the synthesis of the geopolymer. The nomenclature of the pastes and the dosage of the materials are shown in Table 5. Table 4 . Parameters of geopolymer synthesis

Material

%

NaOH (M)

NaOH/NaSi 2 O 3 (Volume)

SiO 2 /Al2O 3

NaOH/Al 2 O 3

ZN

0.5

7, 10, 12

70/30

8.4

0.8-1.2

NaY REF

-

For the preparation of the paste, the following procedure was followed. The AA solution was prepared by mixing the NaOH and water in the indicated molarities and stirring until dissolved. After 24 hours, Na 2 SiO 3 was added, stirring until a homogeneous solution was reached. Dispersion of zeolite additions was performed in the previously prepared solution. Subsequently, the AAS was placed in the mixer with the prepared dispersion and mixed on low speed for one minute. The MK was then added and continued to be stirred for 3 minutes until homogenized. The paste was placed in cubic molds of 2.5x2.5x2.5 cm, then covered with a plastic film and left to rest for 2 hours at room temperature. The cubic specimens were then cured in the oven at a temperature of 60°C for 24 h. They were then