scholarly journals Shape and Size of Particles Scaled from Concrete Surfaces during Salt Frost Testing and Rapid Freeze/thaw in Water

2021 ◽  
Vol 64 (1) ◽  
pp. 53-68
Author(s):  
Marte Beheim Brun ◽  
Andrei Shpak ◽  
Stefan Jacobsen
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Test Methods ◽  
Internal Damage ◽  
Flake Thickness ◽  
Freeze Thaw ◽  
Salt Scaling ◽  
Scale Particle ◽  
Size Of Particles ◽  
Air Void

Abstract Thickness (T), Length (L), Width (W) and size distribution of scaled concrete particles in frost testing were measured. T (mm) increases with particle size surprisingly similarly for different concrete qualities and frost test methods. 2T/(L+W) reduces as function of size and is lowest for the largest particles of the salt scaling test: 0.1 – 0.15 but increases if large aggregate particles scale. Particle size distributions from salt frost testing peak for particles of 1-2 mm. The particles are flakier compared to particles from freeze/thaw in water which also have flatter size distribution no matter type of concrete or degree of damage. Scaling in water is not so efficiently reduced by air voids despite protecting very efficiently against internal damage and scaling in salt frost testing. Comparisons with T predicted by the glue spall model (≈3/4 × ice thickness) and the air void dependent (≈3× critical air void spacing) model proposed by Fagerlund are difficult due to the size dependent flake thickness. Image analysis could well describe shape. Further studies of concrete flake thickness scaled at varying thickness of ice layers are proposed.

Influence of Permeated Crystalline Materials on Durability of Hydraulic Concrete

2012 ◽  
Vol 450-451 ◽  
pp. 1522-1527
Author(s):  
Ke Liang Wang ◽  
Ting Zheng Hu ◽  
Ling Liu
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Transition Zone ◽  
Test Methods ◽  
Sulfate Attack ◽  
Interfacial Transition Zone ◽  
Crystalline Materials ◽  
Freeze Thaw ◽  
Hydraulic Concrete

Influence of permeated crystalline materials on durability of hydraulic concrete was studied by impermeability test methods after sulfate attack and freeze-thaw cycling. Microstructure of concrete was analyzed and characterized with SEM and MIP. The results showed that impermeability pressure of concrete with permeated crystalline materials was more than that of standard concrete after sulfate attack and freeze-thaw cycling. Permeated crystalline materials improved on performance of concrete for sulfate attack and freeze-thaw, because that microstructure of interfacial transition zone of concrete with permeated crystalline materials was compact and its pore size distribution was more than that of standard concrete. There were more content of less harmful pore with diameter 20nm~100nm and less content of harmful pore with diameter100nm~200nm and more than 200nm in concrete with permeated crystalline materials than in standard concrete.

scholarly journals The Study of Particle Size Distribution of Micronized Oat Bran Layer

2020 ◽  
Vol 24 (2) ◽  
pp. 45-54
Author(s):  
Dariusz Dziki ◽  
Wojciech Tarasiuk ◽  
Grzegorz Łysiak ◽  
Paweł Jochymek
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Laser Light ◽  
Rotation Speed ◽  
Raw Material ◽  
Coarse Particles ◽  
Oat Bran ◽  
Size Of Particles ◽  
Sense Of Touch

AbstractThe aim of this work was to study the particle size distribution of micronized oat bran. An impact classified mill was used to pulverizing. Before the pulverizing raw material was sterilized using overheated steam at 150°C during 3.5 min. The moisture of bran after sterilization decreased from 7.2 to about 3.9%. Five speeds of the rotor disc were used: 2600, 2970, 3340, and 3710 rpm. For each speed of the rotor disc the following speeds of classifier wheel were applied: 480, 965, 1450, 1930, 2410 and 2890 rpm. The particle size distribution of oat bran layer was measured by laser light scattering. Moreover, the sense of touch of coarse particles of micronized oat bran on a tongue was assessed according to five point scale. The largest fragmentation of the oat bran was obtained at a disc speed of 3710 rpm and at a classifier rotation speed of 1930 rpm, whereas the most coarse particles were obtained when these parameters were 3340 rpm and 480 rpm, respectively. On the other hand, the highest uniformity in size of particles in size was observed when the lowest speed of disc and classifier were used. Moreover, for the most samples the pulverized particles of oat bran were almost not discernible on tongue.

Investigating the effect of storm events on the particle size distribution in a combined sewer simulator

2005 ◽  
Vol 52 (3) ◽  
pp. 129-136 ◽  
Author(s):  
C.A. Biggs ◽  
C. Prall ◽  
S. Tait ◽  
R. Ashley
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Suspended Solids ◽  
Sediment Type ◽  
Shear Stresses ◽  
Annular Flume ◽  
Sediment Bed ◽  
Median Size ◽  
Size Of Particles ◽  
Consolidation Time

The changes in particle size of sewer sediment particles rapidly eroded from a previously deposited sediment bed are described, using a rotating annular flume as a laboratory scale sewer simulator. This is the first time that particle size distributions of eroded sewer sediments from a previously deposited sediment bed have been monitored in such a controlled experimental environment. Sediments from Loenen, The Netherlands and Dundee, UK were used to form deposits in the base of the annular flume (WL Delft Netherlands) with varying conditions for consolidation in order to investigate the effect of changing consolidation time, temperature and sediment type on the amount and size of particles eroded from a bed under conditions of increasing shear. The median size of the eroded particles did not change significantly with temperature, although the eroded suspended solids concentration was greater for the higher temperature under the same shear stresses, indicating a weaker bed deposit. An increase in consolidation time caused an increase in median size of eroded solids at higher bed shear stresses, and this was accompanied by higher suspended solids concentrations. As the shear stress increased, the solids eroded from the bed developed under a longer consolidation time (56 hours) tended towards a broad unimodal distribution, whilst the size distribution of solids eroded from beds developed under shorter consolidation times (18 or 42 hours) retained a bi- or tri-modal distribution. Using different types of sediment in the flume had a marked effect on the size of particles eroded.

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