Comparison two methods hsm and hem2
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High-shear mixing (HSM) uses laminar shear flow to break up cement agglomerates, while high-energy mixing (HEM) provides increased energy absorption to activate cement hydration and create a nanostructure of CSH gel. HEM absorbs more energy (32,220 J/kg vs. 4,432 J/kg for HSM) and results in a higher rate of hardening, less bleeding, and the ability to use up to 50% fly ash without loss of concrete strength compared to up to 15% for HSM. HEM creates CSH gel through a bottom-up nanotechnology approach, while HSM aims to increase the interface between components through shear stress and rate.
Comparison two methods hsm and hem2
- 1. vfrid38@gmail.com © Copyright 2016 by Vladlen Fridman High Shear Mixing and High-Energy Mixing in Two-Stage mixing concrete M. Yahg: High Shear Mixing (HSM) Vladlen Fridman: High-Energy Mixing (HEM) Cement + Water (Slurry) Cement + Water (Slurry) Cement + Water + Sand (Mortar) Main result of method “Disperse cohesive powders, such as cement powder”, “increase area of interface between the components”, “inhomogeneities are reduced” Increase C-S-H gel formation, accelerate cement hydration. Main idea of method Provide in “laminar shear flow” Shear stress and Shear rate to break cement agglomerates, “ Provide increased Energy absorption to activate cement hydration and create nanostructure of CSH gel (bottom- up approach in Nanotechnology) Parameters of mixing 1/2hp (368wt) Osterizer blender, Speed above 3000 rpm, Energy about 5.5KJ/kg, time 1 min. (M. Yang, H.M. Jennings “Influences of Mixing Methods on the Microstructure And Rheological Behavior of cement Paste”, Elsevier Science Inc., 1995 Energy 5.0-400 KJ/kg, Power 30-600wt/kg, quasi laminar flow, Re number 20-800, Np= 0.1-4.0, time 3-5 min. (Vladlen Fridman, US 20130305963) Comparison of Energy absorption in Mixing process 0 50 100 150 200 250 0 50 100 150 200 250 300 NetPowerwatt/kg Time of mixing, sec Specific Net Power HSM Slurry HEM Slurry HEM Mortar
- 2. Parameters for Processes fulfilled in lab. conditions HSM W/C = 0.37 Absorbed Energy 4432 J/kg, average Re number = 1718, average Np = 0.027 HEM W/C = 0.37 Absorbed Energy 32220 J/kg, average Re number = 529, average Power number Np = 0.15 HEM W/C/S = 0.39/1/2 Absorbed Energy 32108 J/kg, Average Re number 110.5 Average Power number Np = 0.86 Rate of Hardening With Penetration Resistance Method (Tuthill and Cordon) High-Energy Mixed Slurry W/C=0.37 Bleeding water 0.18% of total quantity. Syneresis visible on samples magnified x100 High-Energy mixed mortar W/C/S = 0.39/1/2, High-Shear mixed slurry W/C=0.37 Bleeding water 0.0 % Bleeding water 0.58% of total water Macro-syneresis of HEM activated mortar (evidence of C-S-H gel formation) Allowed quantity of Fly Ash without loss of concrete strength HSM (C+W) No more than 15% of cement quantity ----- HEM (C+W+S) Up to 50% of cement quantity 0 1000 2000 3000 4000 5000 6000 0 2 4 6 8 10 Penetrationresistance,psi Time, hours Control HSM 0 2000 4000 6000 8000 0 5 10 15 penetrationresistance,psi Time, hours control HEM 0 2000 4000 6000 8000 10000 0 2 4 6 8 10 Penetretionresistance,psi Time, hours control HEM
- 3. Power absorption in activation with two methods: HEM and HSM a) Cement – Water mixes High-Shear Mixing, η=55% Re=4874, N=7115,W/C=0.43 High-Shear Mixing, η=34% N=5615, Re=1718 W/C=0.36 High-Shear Mixing, η=10% N=3045rpm,Re=580 W/C=0.37 0 50 100 150 200 250 300 350 0 1000 2000 3000 4000 5000 6000 NetPower,wt/kg Re number Power absorption by the cement-water mixtures High-Energy Mixing, η = 10-54% C-S-H gel Creation Re=20-800, N=600-3000 rpm, w/c=0.26-0.40
- 4. b) Cement – Sand - Water mixes High-Shear Mixing, η=10% N=3045rpm,Re=580 W/C=0.37 0 50 100 150 200 250 300 350 0 1000 2000 3000 4000 5000 6000 NetPowerwt/kg Re number Power absorption by the cement-sand-water mixtures High-Shear mixing,η = 55%, Re=4874, N=7115,W/C=0.43 High-Shear Mixing,η = 34% N=5615, Re=1718 W/C=0.36 High-Energy Mixing, η=10-55% C-S-H gel creation, Re=20-800 N=600-3000rpm, W/C=0.0.36-0.58 C/S=0.25-3.0