Storage of cement

Fig. 1 a Various forms of silo for the storage of cement clinker (capacity about 30000 m ) (from Funke, 1968)... 

The uncontrolled variation in the gypsum-hemihydrate or soluble anhydrite ratio (G-H or A) that occurs during production, storage and transportation of cement can cause compatibility problems with certain superplasticizers, particularly a reduction in workability. The extent of the reduction on workability properties is dependent on the G-H ratio (ranging from 80 20% to 20 80%), level of C3A and alkalis present in the cement and the fineness of... 

The uncontrolled variation in the gypsum-hemihydrate or soluble anhydrite ratio (G-H or A) that occurs during production, storage and transportation of cement can cause compatibility problems with certain superplasticizers, particularly a reduction in workability. The extent of the reduction on workability properties is dependent on the G-H ratio (ranging from 80 20% to 20 80%), level of C A and alkalis present in the cement and the fineness of the cement. For the most reactive type of cement with a high content of both C A and alkalis, a reduced G-H or A ratio affects the yield stress, while piastre viscosity is not much affected. These effects are much less pronounced for a less reactive cement, but with the lowest G-H or A ratio, false set can occur [130-132], An increased fineness of cement increases the effect of the G-H or A ratio. The effect has been found to be most pronounced with melamine-based superplasticizers [130, 133],... 

Three items are important in the storage of admixtures, namely, the ease of identification, humidity and temperature at which they are stored. To avoid confusion between different admixtures, drums should be delivered clearly labeled as to the contents identification can be made easier by a colorant which has no influence on the concrete. Powdered admixtures are more sensitive to moisture and carbon dioxide than are Portland cements. The materials should, therefore, be packed in waterproofed bags and always stored in areas free of high relative humidity and temperature extremes to avoid condensation. Storage tanks should be vented properly, and fill nozzles and any other tank openings should be capped when not in use to avoid contamination. 

Concrete biodeterioration in radioactive-waste disposal Safe long-term storage of nuclear waste is of importance in protecting the environment. Cement and concrete are used as barriers in all... 

Compressive strength is historically one of the best measures of cement quality and will be useful for design purposes for the RSSF (the Retrievable Surface Storage Facility). 

Promising forms will be heated for several months at the normal storage temperature and at 100°G to determine possible ill effects. The maximum specific power of cement waste forms would be / 0.4 W/1. with normal storage temperatures around 60°C. 

The cementation and bitumenization techniques are also used for intermediate level wastes arising in other parts of the nuclear fuel cycle, e.g. reprocessing. The long-term storage of the solidified waste is described in Chapter 21 and some of its possible future impact on the environment in Chapter 22. 

P-13 - Permanent storage of chromium in hardened FAU-type zeolite /cement pastes... 

Oxides and mixed catalysts Manufacturing of cement, concrete Refractory ceramics, a brick Faience and porcelain Safe life of medicines Terms and conditions of safe storage Recycling (processing) of products Formation and evolution of breeds (karsts) Evolution of the Solar System and the Universe Development of technologies for the production of materials for optoelectronics (GaN)... 

Physical and chemical properties of Biodentine are shown in Table 9.8. The material can be seen to set rapidly, and to have a reasonable compressive strength and Vicker s Hardness Number at 24h [85,86]. It shows a snbstantial wash out (solubility) in Hank s balanced salt solution (HBSS), which is presumably at least matched in deionized water. However, the pH of deionized water following storage of set Biodentine is only around 9 at 24h, rather than the 11-12.5 of traditional calcium hydroxide chelate cements or supersaturated solution. This may suggest that Biodentine is less bioactive than such materials, and hence less effective at promoting the growth of reparative dentine. 

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