Aggregate sizes

Aggregate size depends on solution chemistry, hydrodynamic conditions when aggregates are formed, and the presence of organics. To understand the aggregation formation, at first simple systems were looked at, that is 10 mgL hematite, pH 3 and ionic strength varied using KCl. The critical coagulation concentration for KCl in these systems was 65 mM as shown in Chapter 6. 

In more applied experiments more complex systems were used. Particle siae analysis was only possible in the SPO mixing order. In the OPS order, the aggregates were too small and the scattered light intensity was very low. 

For the systems mixed in OPS order, no size was measured. The Malvern instrument signal was too low for these systems. Since the rejection of these stabilised systems was so low in MF, it is assumed that the size of these colloids is not larger than primar) colloids plus an adsorbed organic layer (thickness 1 to 2 nm). 

Aggregate size (mm) Minimum field sample mass of aggregates (kg) Minimum mass for sieving, per batch (kg) 

Regarding combined coarse and fine aggregates, the minimum weight shall be that of the coarse aggregate plus 10 kg. 

According to American standards, the minimum mass of aggregate for sieving, as well as for initial sampling, is presented in Table 2.6. 

During sieving, the overloading of each sieve should be avoided. According to CEN EN 933-1 (2005), to avoid overloading , the portion retained on each sieve at the end shall not be over the specified proportion, expressed in grams, which is determined by the following equation  

If the retained portion on a sieve is larger than the one determined by the above equation, the portion is divided into two or three smaller parts and further sieving is carried out by hand. Finally, to determine the final portion retained, the subportions retained on a sieve are combined for the particular sieve. 

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By request of the owner, two concrete test cores (0 15cm) were drilled out of the building. The wall thickness was determined at 25cm, with the maximum aggregate size being about 32mm. 

Fig. 4. Aggregate size distributions by electron microscope image analysis (D and centrifugal (Z9 sedimentations for N220 and N351 carbon blacks (8).

Ref. 10. Particle size, aggregate size, and surface area are by em. 

Surface Area. The most important features influencing the performance of carbon blacks are aggregate size and surface area. Surface area is measured by gas- and Hquid-phase adsorption techniques, and depends on the amount of adsorbate required to form a surface monolayer. If the area occupied by a single-adsorbate molecule is known, a simple calculation will yield the surface area. A low temperature nitrogen absorption method, based on the original method of Bmnauer, Emmett, and Teller (BET) (30), has been adopted by ASTM as standard method D3037-86 (2). 

Particle and aggregate size are the most important factors in carbon blacks. During the manufacture of carbon blacks, primary particles are obtained in the... 

The expansion index [51,102,103], defined as the ratio of cell fresh weight to dry weight evaluated at the time of maximum fresh weight, is a more qualitative indicator of changes in cell/aggregate size, under various cultivation conditions. Wongsamuth and Doran [58] identified the filtration characteristics of suspensions of Atropa belladonna, specifically cake permeability, which is at least partially related to morphology, as a useful indicator of shear effects. 

Daucus carota Petunia mitchelle Glycine soja Haake rotoviscometer (paddle system) turbulent mitochondrial activity cell lysis (cell no.) aggregate size non-growth [57, 69]... 

Cone-and-plate viscometers have been employed to study shear effects in both suspended (e.g. [138]) and anchorage dependent [122] mammalian cells. These devices have the advantage of requiring only small sample volumes ( lml). However, they are generally inappropriate for plant cell suspensions due to the larger cell and aggregate sizes. 

Stizolobium hassjoo 125-ml shake flasks 140-220 rpm (0.4-1.7 m s- ) secondary metabolite production aggregate size [45]... 

Table 2.7 lists techniques used to characterise carbon-blacks. Analysis of CB in rubber vulcanisates requires recovery of CB by digestion of the matrix followed by filtration, or by nonoxidative pyrolysis. Dispersion of CB within rubber products is usually assessed by the Cabot dispersion test, or by means of TEM. Kruse [46] has reviewed rubber microscopy, including the determination of the microstructure of CB in rubber compounds and vulcanisates and their qualitative and quantitative determination. Analysis of free CB features measurements of (i) particulate and aggregate size (SEM, TEM, XRD, AFM, STM) (ii) total surface area according to the BET method (ISO 4652), iodine adsorption (ISO 1304) or cetyltrimethylammonium bromide (CTAB) adsorption (ASTM D 3765) and (iii) external surface area, according to the dibutylphthalate (DBP) test (ASTM D 2414). TGA is an excellent technique for the quantification of CB in rubbers. However, it is very limited in being able to distinguish the different types of... 

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