Shrink Shrinkage

Form-sand, m. molding sand, -schwindung, /. shrinking, shrinkage, -stahl, m. structural steel profile steel, -stein, m. shaped brick (Lead) pipe stone, -stiiek, n. shaped part, -ton, m. molding clay. 

We can imagine the coil tightening up as this point is approached from better conditions. This is not a shrinking to the vanishing point as suggested by the u = 0 criterion, but a contraction to the point where intramolecular exclusion effects are offset by shrinkage. 

Permanent chemical crimp can be obtained by creating an asymmetric arrangement of the skin and the core parts of the fiber cross section. Skin cellulose is more highly ordered than core cellulose and shrinks more on drying. If, during filament formation in the spin bath, the skin can be forced to burst open to expose fresh viscose to the acid, a fiber with differing shrinkage potential from side-to-side is made, and crimp should be obtained (Fig. 5a). 

Expansire cements are hydrauHc cements designed to expand rather than shrink on curing, as do standard Pordand cements. They are defined in ASTM C845 and are used to control and reduce shrinkage cracks in large poured-in place stmctures. 

Wood While fairly inert chemically, wood is readily dehydrated by concentrated solutions and hence shrinks badly when subjected to the action of such solutions. It is also slowly hydrolvzed by acids and alkalies, especially when hot. In tank construction, if sufficient shrinkage once takes place to allow ctystals to form between the staves, it becomes very difficult to make the tank tight again. 

When concrete hardens, the cement paste shrinks. The gravei, of course, is rigid, so that smaii shrinkage cracks are created. It is found that air entrainment (mixing small bubbles of air into the concrete before pouring) helps prevent the cracks spreading. 

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