EPOXY RESIN CHEMICALLY RESISTANT MORTARS

C 579 Standard Test Method for Compressive Strength of (Method B) Chemical Resistant Mortars and Monolithic Surfacings C 882-87 Standard Test for Bond Strength of Epoxy-Resin Systems Used with Concrete C 884-87 Standard Test Method for Thermal Compatibility between Concrete and an Epoxy-Resin Overlay... 

Polyester and Vinyl Ester Mortars These two mortars, of which there are many types, are suitable for a pH range of about 0-11 and a continuous service temperature of 225°-230°F. The two related resins, which complement the epoxy resins, resist dilute and concentrated acids and weak alkalies. Their resistance to acid bleaches such as chlorine dioxide and to oxidizing acids such as nitric and chromic is superior to that of other resinous mortars, and they are excellent in acetic acid and related esters. However, polyester and vinyl ester mortars are the poorest resin mortars in other organic chemical exposures including solvents in general. Such mortars are widely used in paper mills and are suitable with acid brick or ceramic tile in the lower temperature zones of mildly acidic utility FGD systems. 

The classic thermosets, such as ebonite, phenolics, ureas, melamines and polyesters as well as the epoxies, when reinforced with fiberglass or graphite fibers could also be classified as high performance thermosets. While these plastics cannot be readily extruded or injection molded, they are resistant to the effects of moderately high hostile environments. Phenolic resin mortars have been used for over a half century for the construction of chemical resistant vessels and for joining brick and tile used as linings in hot acid environments. (1.)... 

Epoxy mortars are less frequently used in CRM than other resin bonded systems due to higher cost, lower maximum service temperature, and narrower range of chemical resistance. However, because of their excellent bond strength to concrete, epoxides are frequently used for acid brick floors over concrete. They also have applications in alkali exposure. 

For applications such as swimming pools and water-purification tanks, for which chemical resistance is required, or where resistance to dynamic stress is needed, special epoxy resins are used. Blends of a waterborne synthetic emulsion with a cement compound are suitable for applications with lower requirements. In some cases, e.g. sewage-treatment plants, elastomer-modified bitumen mortars are still used. 

Figure 9 exhibits the weight change of epoxy-modified mortars immersed in various test solutions for 28 days. It appears that the chemical resistance of the epoxy-modified mortars is superior to that of unmodified mortar because of the excellent chemical resistance of the epoxy resin used. 

Epoxy Mortars Epoxies are the strongest resin mortars, have the best bond strength to other CRM materials, and resist many solvents, mild to moderate acids, non-oxidizing and alkaline media. Their useful pH range is about 2-14, and their thermal limit is approximately 230°F. Besides their excellent alkali and dilute acid resistance, epoxy mortars handle many organic chemicals and sodium hypochlorite at low temperatures. Epoxies should not be exposed to acetic acid and its esters. Epoxy mortars have the best physical and mechanical properties of all the resin mortars. 

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