Was carried out in samples immersed in an acid answer of pH = 1. Wetting-drying cycle experiment was applied for the test of acid corrosion resistance. The properties have been characterized by visual appearance, compressive strength, mass loss, and neutralization depth. SEM, XRD, and FTIR were chosen to analyze the mechanism of acid corrosion resistance for GPC.Components 2021, 14,3 of2. Experimental Specifics two.1. Raw Materials Three forms of binding materials, like as low-calcium fly ash, high-calcium fly ash, and metakaolin, had been adopted to prepare the GPC. The low-calcium fly ash was Class-F, whose content material of CaO was less than ten . The higher calcium fly ash was Class-C, and its content material of CaO was more than ten . Difamilast supplier metakaolin was purchased from Gongyi, Henan Province. The chemical compositions of your low-calcium fly ash, high-calcium fly ash, and metakaolin were measured by X-ray fluorescence (XRF), as shown in Table 1. The coarse aggregate was natural SK-0403 supplier limestone with the size of 4.75.five mm. Washed river sand was chosen as fine aggregate. The reagents of sodium hydroxide (NaOH 96.0 , AR), sulfuric acid (H2 SO4 95.0 , AR), and phenolphthalein (1) were purchased from Sinopharm Chemical Reagent Co., Ltd., Shanghai, China. Sodium silicate liquid (Na2 SiO3 with 29.9 wt SiO2 , 13.75 wt Na2 O, and 56.35 wt H2 O) as well as the distilled water have been applied within the experiments.Table 1. Chemical compositions of binding supplies (wt.). Chemical Compositions Class F fly ash Class C fly ash Metakaolin SiO2 44.94 44.18 48.88 Al2 O3 32.15 26.92 43.39 Fe2 O3 five.14 9.34 3.aSO3 2.07 1.53 0.TiO2 1.49 1.34 two.CaO 9.90 11.02 0.K2 O 1.13 1.39 0.MgO 1.04 1.88 -Na2 O 0.81 1.29 -LOI a 1.33 1.11 0.LOI: Loss on ignition.2.2. Mix Proportions and Preparation of Specimens The GPC have been ready with binding components and an alkaline solution which was a mixture of Na2 SiO3 and distinctive concentrations of NaOH (8 M and 12 M) pre-mixed having a ratio (Na2 SiO3 /NaOH) of 1.five. The mix proportions for all GPC mixtures are listed in Table two.Table 2. Proportions of mixtures (kg/m3). Mixes F-8 F-12 C-8 C-12 MK-8 MK-12 Binding Components Class F 377 377 Class C 450 450 Metakaolin NA 1150 1150 1150 1150 1150 1150 Sand 500 500 500 500 500 500 NaOH 8M 108 108 108 12 M 108 108 108 Na2 SiO3 162 162 162 162 162 162 Free Water 60-399The preparation course of action of GPC is shown in Figure 1. The cylindrical specimens with 50 100 mm in dimension have been prepared for tests. It needs to be noted that the GPC specimens needed to become filled in three layers. After filling, the specimens have been vibrated on the vibrating table for 30 s to eliminate the bubbles inside. Then, they were put into hermetic bags and cured at 60 C for 48 h. Subsequently, the GPC specimens cooled for 1 h have been demolded and preserved within a regular curing space (20 two C, RH 95) until the age of 7 d. In line with the kinds of binding components and concentrations of NaOH, the GPC specimens prepared with low-calcium and high-calcium fly ash and metakaolin were marked as F-8, F-12, C-8, C-12, MK-8, and MK-12 respectively.Materials 2021, 14, 7109 PEER Critique Components 2021, 14, x FORof 17 44 ofFigure 1. Preparation diagram of GPC. Figure 1. Preparation diagram of GPC.2.3. Measurements two.3. Measurements two.three.1. Sulfuric Acid Corrosion Resistance Test two.three.1. Sulfuric Acid Corrosion Resistance Test Before the sulfuric acid corrosion resistance test, all the GPC specimens had been polished Just before surface working with sandpaper to clean up test, all the GPC specimens have been p.