Aggregates particle density

Classification of the constituents of coarse recycled aggregates Particle density and water absorption CEN EN 933-1 1 (2009) Yes... 

The European standard describing the procedure for the determination of aggregate particle density as well as the determination of water absorption is CEN EN 1097-6 (2005). The corresponding American standards are ASTM C 127 (2012) (AASHTO T 85 2013) and ASTM C 128 (2012) (AASHTO T 84 2013). 

The determination of aggregate particle density between 0.063 and 4 mm using the pyknometer method is similar to the method for aggregate particles between 4 and 31.5 mm. The key difference is the amount of aggregate tested, which should not be less than 1 kg. 

Assumed particle density = 1.82 g mL-1 with an SiO. content of 92.7 wtc/r. c Number of TEOS molecules per aggregate. 

Despite the fact that this hydraulic density is essential to many calculations involving fluidization and the suspension of particles, it is characteristic that in the related literature, authors use the terms particle density or solid density without specifying if the fluid in the pores has been taken into account. However, the subject of hydraulic density has been analyzed in studies of the behavior of impermeable aggregates in fluids. As these aggregates could be seen as porous particles, the relevant analysis is interesting and will be presented here. 

Therefore, in the symmetric situation, D = D, the recombination kinetics may be also separated into two subsequent stages of dynamic and statistical aggregation. At long times the particle density in these aggregates (domains), characterized by the maximum values of the correlation functions Xu(r —> 0,t), is not very high. The reaction rate is governed by the ratio of two distinctive spatial scales — and re. 

As it was noted in [77], reduction of the reaction rate with time observed for non-interacting particles at high concentrations/long reaction times, Section 6.2, is unlikely to occur for charged particles since spatial fluctuations in particle densities are now governed not by (i) but the screening radius in other words, the Coulomb repulsion of similar particles prevents their aggregation. 

In this Chapter the kinetics of the Frenkel defect accumulation under permanent particle source (irradiation) is discussed with special emphasis on many-particle effects. Defect accumulation is restricted by their diffusion and annihilation, A + B — 0, if the relative distance between dissimilar particles is less than some critical distance 7 0. The formalism of many-point particle densities based on Kirkwood s superposition approximation, other analytical approaches and finally, computer simulations are analyzed in detail. Pattern formation and particle self-organization, as well as the dependence of the saturation concentration after a prolonged irradiation upon spatial dimension (d= 1,2,3), defect mobility and the initial correlation within geminate pairs are analyzed. Special attention is paid to the conditions of aggregate formation caused by the elastic attraction of particles (defects). 

Of special interest in the recent years was the kinetics of defect radiation-induced aggregation in a form of colloids-, in alkali halides MeX irradiated at high temperatures and high doses bubbles filled with X2 gas and metal particles with several nanometers in size were observed [58] more than once. Several theoretical formalisms were developed for describing this phenomenon, which could be classified as three general categories (i) macroscopic theory [59-62], which is based on the rate equations for macroscopic defect concentrations (ii) mesoscopic theory [63-65] operating with space-dependent local concentrations of point defects, and lastly (iii) discussed in Section 7.1 microscopic theory based on the hierarchy of equations for many-particle densities (in principle, it is infinite and contains complete information about all kinds of spatial correlation within different clusters of defects). 

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