EVA-modified

The reduction in porosity, decreased water content, and air entrainment that results when latexes are used in mortar and concrete mixes make them much more resistant to freezing and thawing conditions than conventional mortar and concrete. Figure 6.17 presents the freeze-thaw durability in water (-18 to 4°C) of combined water-and dry-cured SBR-, PAE- and EVA-modified mortars [98], The frost resistance of mortars made with these latexes is markedly improved even at polymer-cement ratios of 5%. However, an increase in the polymer-cement ratio does not necessarily produce further improvement in freeze-thaw resistance. EMM and EMC, when exposed to outdoor conditions involving freeze-thaw, UV radiation and carbonation show better weatherability when compared with conventional mortar and concrete. 

The effects of blended cements containing various mineral admbc-tures on the flexural strength of dry-cured EVA-modified mortars are illustrated in Fig. 4.17.The flexural strength of EVA-modified mortars with the blended cements increases with an increase in the polymer-cement ratio, and is similar to that of unmodified mortar except in a few cases. 

Figure 4.17 Effects of blended cements on flexural strength of dry-cured EVA-modified mortars. (O 1993, Advances in Cement Research, Thomas Telford Services Ltd., reprinted with permission.)...

COMPRESSIVE STRAIN xIO" COMPRESSIVE STRAIN,xIO COMPRESSIVE STRAIN, xlO- S -MOofFlIb PAE-MODIRED MORTAR EVA-MODIFIED MORTAR... 

DEFLECTION,. xlO mm Figure 4.33 Flexural load-deflection curves for steel fiber reinforced SBR- and EVA-modified mortars. 

Figure 4.36 Effect of bound ethylene content on 28-day drying shrinkage of EVA-modified mortars.

Figure 4.37 Volume-surface area ratio and polymer-cement ratio vs. drying shrinkage of EVA-modified concretes.

WATER IMMERSION PERIOD, hours EVA-MODIFIED MORTAR... 

Figure 4.44 shows the water permeability as measured parameter, time (s), by Figg s methodi 1 of dry-cured EVA-modified mortars with blended cements containing various mineral admixtures. According to this method, the measured parameter is the time taken for a standard volume of water to be permeated into the specimen through a 10 nun diameter x 40 mm deep hole.P 1 An increase in the measured parameter of EVA-modified mortars with the blended cements indicates a decrease in the water perme-ability, and increasing polymer-cement ratio decreases the water permeability by a factor of 10 or more. 

Figure 4.48 Relation between bound ethylene content and flexural and compressive strengths of EVA-modified mortars.

The thermal resistance of latex-modifled mortar and concrete is governed by the nature, especially glass transition temperature of polymers used, polymer-cement ratio, and heating conditions, and ultimately by the thermal degradation of the polymers. Figure 4.59f l indicates the thermal resistance of SBR-, PAE-, and EVA-modified mortars at 100 to 200°C. The flexural strength of most latex-modified mortars at 100°C tends to initially... 

D.A Silva and P.J.M.Monteiro, ESEM analysis of polymeric film in EVA-modified cement paste. Cement and Concrete Research, Vol 35 (2005) p. 2047... 

Carswell J. 1987. The Effect of EVA Modified Bitumen on Roiled Asphalt Containing Different Fine Aggregates. TRRL RR122. Wokingham, UK Transport Research Laboratory. 

With regard to the solvents, toluene, trichloroethylene, dichloromethane and tetrachlo-roethylene are generally able to satisfactorily dissolve the styrene butadiene styrene (SBS) modified binders. Toluene, trichloroethylene and tetrachloroethylene are sometimes suitable for ethylene vinyl acetate (EVA)-modified binders. Dichloromethane is generally not suitable for EVA-modified binders. Few solvents have been found to be suitable to dissolve atactic polypropylene (APP)-modified binders completely the best solubility with such a modifier is obtained with hot xylene. 

Cellulose acetate butyrate, CAB, is used for toys, pen and pencil barrels, decorative plaques, tool handles and machine guards. Because of its toughness and sweat resistance the material is used in steering wheels and suitcase handles. EVA-modified materials available, which are more temperature and weather resistant than plasticized compounds. 

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