Freeze-thaw expansion

Com symp soflds are also dry products, have a smaller average size, and are comparatively sweeter (12). Both maltodextrins and com symp soflds are used to prevent caking enhance dispersibiUty and solubiUty provide body or bulk impart deskable texture bind, carry, and protect flavors control extmsion expansion provide viscosity form films and coatings provide an oxygen barrier inhibit crystallization control sweetness improve sheen improve organoleptic characteristics slow meltdown and improve freeze—thaw stabiUty. 

A stabilising effect in the presence of salt was also noted by Aronson and Petko [90]. Addition of various electrolytes was shown to lower the interfacial tension of the system. Thus, there was increased adsorption of emulsifier at oil/water interface and an increased resistance to coalescence. Salt addition also increased HIPE stability during freeze-thaw cycles. Film rupture, due to expansion of the water droplets on freezing, did not occur when aqueous solutions of various electrolytes were used. The salt reduced the rate of ice formation and caused a small amount of aqueous solution to remain unfrozen. The dispersed phase droplets could therefore deform gradually, allowing expansion of the oil films to avoid rupture [114]. 

For concrete, deterioration due to freeze-thaw is caused bj freezing of pore water inside the concrete. If the pores are too small, then the expansion caused by freezing can exert stresses on the concrete that crack the concrete and thus cause deterioration. Air entrainment of 7-8 %, depending on the aggregate size, can essentially eliminate this freeze-thaw damage [3]. 

Popping is caused by the expansion of a particle (e.g., of chalk in concrete as a result of freeze-thaw cycles, and of unsound slaked lime in lime mortar) and results in lifting of the surface. 

Latex-modified mortar and concrete have improved resistance to freezing and thawing, i.e., frost attack, over conventional mortar and concrete. This is due to the reduction of porosity as a result of decreased water-cement ratio and filling of pores by polymers, and the air entrainment introduced by polymers and surfactants. Figures 4.66 and 4.67 represent the freeze-thaw durability in water (-18 to 4°C) of combined water and dry-cured SBR-, PAE-, and EVA-modified mortars.The frost resistance of SBR-, PAE-, and EVA-modified mortars is improved markedly at polymer-cement ratios of 5% or more. As the degree of expansion by frost (calculated... 

Delamination of the MPL from the GDL substrate has not been widely reported but may occur during freeze-thaw cycles, as occurs with catalyst-layer delamination from the membrane [131, 132]. A different situation occurs in the GDL/MPL, where the pore diameters are on the order of a micron or larger and the water is not hydrating the sulfraiic acid of the ionomer. The volume expansion caused by ice formation can produce large isotropic stresses that can damage the structure of the catalyst layer, the MPL, or the GDL. 

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