Phosphogypsum-based materials (PBM) were synthesized with varied phase compositions of phosphogypsum,portland cement and fly ash.Effects of fractal growth characteristics on physicochemical properties,pore structure,c...Phosphogypsum-based materials (PBM) were synthesized with varied phase compositions of phosphogypsum,portland cement and fly ash.Effects of fractal growth characteristics on physicochemical properties,pore structure,compressive strength,as well as the hydration behaviour and mineralogical conversion of mortars were examined by a multitechnological approach,including mercury intrusion porosimetry,rietved phase analysis,thremal analysis,calorimetry and Fourier transforminfrared spectroscopy analysis.Expermental results indicate that the specimens cured with mosite resulted in higher strength and lower porosity compared with those cured in the drying chamber.In addition,a more complicated course of the aluminate and silicate reactions during the hydration process has been published,with the hydration products mainly consisting of calcium silicate hydrate (C-S-H),portlandite,ettringite,hemicarbonate,monocarboaluminate,calcite,quartz,a mixed AFm passed with carbonate,and hydroxide.After all,the nucleation process is a reaction that can be defined as a solid,liquid and gaseous phases that goes through the four stages of materialization mixing and modification,i e,hydration of low calcium content,secondary hydration,high calcium condensation and geoplymensation,respectively.The rupture,recombination,polymerization reactions of Si-O,Ca-O,Al-O bonds contribute to the nucleation mechanism that serves as the formation of C-S-H in hydration products.展开更多
The formations of [NAPA-A(H<sub>2</sub>O)<sub>n</sub> (n = 1, 2, 3, 4)] complexes have been studied employing DFT/wB97XD/cc-pVTZ computational level to understand the kinetics and thermodynamic...The formations of [NAPA-A(H<sub>2</sub>O)<sub>n</sub> (n = 1, 2, 3, 4)] complexes have been studied employing DFT/wB97XD/cc-pVTZ computational level to understand the kinetics and thermodynamics for the hydration reactions of N-acetyl-phenylalaninylamide (NAPA). Thermodynamic parameters such as reaction energy (E), enthalpy (H), Gibb’s free energy (G), specific heat capacity (C<sub>v</sub>), entropy (S), and change of these parameters (ΔE<sub>r</sub>, ΔH<sub>r</sub>, ΔGr, ΔC<sub>r</sub>, and ΔS<sub>r</sub>) were studied using the explicit solvent model. The predicted values of H, G, C, and S increase with the sequential addition of water in NAPA-A due to the increase in the total number of vibrational modes. On the other hand, the value of ΔE<sub>r</sub>, ΔH<sub>r</sub>, and ΔG<sub>r</sub> increases (more negative to less negative) gradually for n = 1, 2, 3, and 4 that indicates an increase of hydration in NAPA-A makes exothermic to endothermic reactions. The barrier heights for the transition states (TS) of [NAPA-A(H<sub>2</sub>O)<sub>n</sub> (n = 1, 2, 3, 4)] complexes are predicted to lie at 4.41, 4.05, 3.72 and 2.26 kcal/mol respectively below the reactants. According to the calculations, the formations of [NAPA-A(H<sub>2</sub>O)<sub>1</sub>] and [NAPA-A(H<sub>2</sub>O)<sub>2</sub>] complexes are barrierless reactions because both water molecules are strongly bonded via two hydrogen bonds in the backbone of NAPA-A. On the contrary, the reactions of [NAPA-A(H<sub>2</sub>O)<sub>3</sub>] and [NAPA-A(H<sub>2</sub>O)<sub>4</sub>] complexation are endothermic and the barrier heights are predicted to stay at 6.30 and 10.54 kcal/mol respectively above the reactants. The free energy of activation (Δ<sup>‡</sup>G<sup>0</sup>) for the reaction of [NAPA-A(H<sub>2</sub>O)<sub>1</sub>], [NAPA-A(H<sub>2</sub>O)<sub>2</sub>], [NAPA-A(H<sub>2</sub>O)<sub>3</sub>], and [NAPA-A(H<sub>2</sub>O)<sub>4</sub>] complexation are 4.43, 4.28, 3.83 and 5.11 kcal/mol respectively which are very low. As well as the rates of reactions are 3.490 × 10<sup>9</sup> s<sup>-1</sup>, 4.514 × 10<sup>9</sup> s<sup>-1</sup>, 9.688 × 10<sup>9</sup> s<sup>-1</sup>, and 1.108 × 10<sup>9</sup> s<sup>-1</sup> respectively which are very fast and spontaneous.展开更多
文摘Phosphogypsum-based materials (PBM) were synthesized with varied phase compositions of phosphogypsum,portland cement and fly ash.Effects of fractal growth characteristics on physicochemical properties,pore structure,compressive strength,as well as the hydration behaviour and mineralogical conversion of mortars were examined by a multitechnological approach,including mercury intrusion porosimetry,rietved phase analysis,thremal analysis,calorimetry and Fourier transforminfrared spectroscopy analysis.Expermental results indicate that the specimens cured with mosite resulted in higher strength and lower porosity compared with those cured in the drying chamber.In addition,a more complicated course of the aluminate and silicate reactions during the hydration process has been published,with the hydration products mainly consisting of calcium silicate hydrate (C-S-H),portlandite,ettringite,hemicarbonate,monocarboaluminate,calcite,quartz,a mixed AFm passed with carbonate,and hydroxide.After all,the nucleation process is a reaction that can be defined as a solid,liquid and gaseous phases that goes through the four stages of materialization mixing and modification,i e,hydration of low calcium content,secondary hydration,high calcium condensation and geoplymensation,respectively.The rupture,recombination,polymerization reactions of Si-O,Ca-O,Al-O bonds contribute to the nucleation mechanism that serves as the formation of C-S-H in hydration products.
文摘The formations of [NAPA-A(H<sub>2</sub>O)<sub>n</sub> (n = 1, 2, 3, 4)] complexes have been studied employing DFT/wB97XD/cc-pVTZ computational level to understand the kinetics and thermodynamics for the hydration reactions of N-acetyl-phenylalaninylamide (NAPA). Thermodynamic parameters such as reaction energy (E), enthalpy (H), Gibb’s free energy (G), specific heat capacity (C<sub>v</sub>), entropy (S), and change of these parameters (ΔE<sub>r</sub>, ΔH<sub>r</sub>, ΔGr, ΔC<sub>r</sub>, and ΔS<sub>r</sub>) were studied using the explicit solvent model. The predicted values of H, G, C, and S increase with the sequential addition of water in NAPA-A due to the increase in the total number of vibrational modes. On the other hand, the value of ΔE<sub>r</sub>, ΔH<sub>r</sub>, and ΔG<sub>r</sub> increases (more negative to less negative) gradually for n = 1, 2, 3, and 4 that indicates an increase of hydration in NAPA-A makes exothermic to endothermic reactions. The barrier heights for the transition states (TS) of [NAPA-A(H<sub>2</sub>O)<sub>n</sub> (n = 1, 2, 3, 4)] complexes are predicted to lie at 4.41, 4.05, 3.72 and 2.26 kcal/mol respectively below the reactants. According to the calculations, the formations of [NAPA-A(H<sub>2</sub>O)<sub>1</sub>] and [NAPA-A(H<sub>2</sub>O)<sub>2</sub>] complexes are barrierless reactions because both water molecules are strongly bonded via two hydrogen bonds in the backbone of NAPA-A. On the contrary, the reactions of [NAPA-A(H<sub>2</sub>O)<sub>3</sub>] and [NAPA-A(H<sub>2</sub>O)<sub>4</sub>] complexation are endothermic and the barrier heights are predicted to stay at 6.30 and 10.54 kcal/mol respectively above the reactants. The free energy of activation (Δ<sup>‡</sup>G<sup>0</sup>) for the reaction of [NAPA-A(H<sub>2</sub>O)<sub>1</sub>], [NAPA-A(H<sub>2</sub>O)<sub>2</sub>], [NAPA-A(H<sub>2</sub>O)<sub>3</sub>], and [NAPA-A(H<sub>2</sub>O)<sub>4</sub>] complexation are 4.43, 4.28, 3.83 and 5.11 kcal/mol respectively which are very low. As well as the rates of reactions are 3.490 × 10<sup>9</sup> s<sup>-1</sup>, 4.514 × 10<sup>9</sup> s<sup>-1</sup>, 9.688 × 10<sup>9</sup> s<sup>-1</sup>, and 1.108 × 10<sup>9</sup> s<sup>-1</sup> respectively which are very fast and spontaneous.
