Brick particles spacing

Residual length changes of concrete specimens subjected to freezing-thawing cycles and containing brick particles (total porosity, 16%) are recorded in Table 1. The basic concrete mix had a cement aggregate sand ratio 1 2.75 2.25 and a water cement ratio of 0.58. The spacing factors for the concretes listed in Table 1 were 0.046, 0.013,0.033, 0.029, and 0.033 respectively. 

However, you may be surprised to learn that you are constantly being bombarded with low levels of radiation. This radiation comes from many sources and is referred to as backgrormd radiation. Some of it is in the form of cosmic rays, which are particles that reach Earth from outer space. Small amormts of radioactive elements are found almost everywhere on Earth, as well—in wood and bricks used to make buildings, in the fabrics used in clothing, in the foods you eat, and even inside your body. Traces of uranium in rock layers beneath houses may also produce radioactive radon gas that enters the houses and can present health risks. Various sources of radiation are illustrated in Figure 21.20. 

The filter media made from crashed fire bricks or quartz pieces is filled in the two concentric stainless steel screens (annular space between the screens). Dust particles are filtered and the clean gas goes out from the top outlet nozzle. When the pressure drop increase to a predetermined limit, it can be drained out quickly, and restarted again by filling in fresh filter media kept ready beforehand. This needs only a small stoppage of the plant gas flow. 

The spacing of brick particulates (distance between particle surfaces) is linearly related to the particle diameter for a given volume concentration. Freezing-thawing cycles expressed as the number of cycles required to produce 0.2% residual expansion is plotted versus spacing in Fig. 29 for cement paste, w/c = 0.50 and wet cured for 28 days. There is a dramatic increase in the number of cycles when the spacing is reduced below 0.8 mm. 

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