Asphalt water-stripping

Previous investigators have drawn attention to the beneficial effect of lime when added in small quantities to asphaltic bitumen. The lime helps retard oxidative hardening (13) and reduces the tendency towards water-stripping (4,11,12). Most asphalts are slightly acidic because of the presence of phenolic or carboxylic substituents and would therefore react with basic oxides to form insoluble salts. For example, Fromm (10) has described the use of iron salts of naphthenic acids as adhesion promoters to improve the water resistance of asphalt concretes. This promising approach is now undergoing commercial trials. The literature also describes methods of chemically modifying asphalt with maleic anhydride or acrylic acid (14), sulfur trioxide (15), sulfur dioxide (16), acetyl sulfate (17-21), and sulfuric acid (20). (For a recent review of the interfacial phenomena in asphaltic compositions see Ref. 4.)... 

A growing use for hydrated lime, particularly in the United States, is as an additive to hot mix asphalt [26.21, 26.22]. The main benefit is that it increases the resistance of the asphalt to water stripping. Lime also acts as a mineral filler and as an antioxidant. 

Uses Coating additive in asphalt cement and cutbacks, stockpile mixes water stripping... 

Examination of Sulphlex-233 mixtures with other types of aggregates generally have confirmed the results presented here. Sulphlex-233 mixtures can meet or exceed most Marshall design and compressive strength criteria at either equal volume or equal weight replacement of asphalt cement, but "optimum" mixtures are obtained at or near the equal volume replacement level. The Sulphlex-233 mixtures are in many cases susceptible to water damage, and the use of tall oil as an anti-strip additive has been recommended where indicated. 

Resistance to Water. A common cause of pavement failure in many areas is stripping of the asphalt from the aggregate by the action of water. The tendencies of stripping by water can be reduced greatly by... 

The lap-shear test was used to determine the room-temperature cohesive strength of the modified asphalts and to follow the thickening process in both air and water. Two aluminum strips 1 mm thick and 2.5 cm wide were overlapped 2.5 cm and firmly bonded together with a drop of molten asphalt. The test pieces were held in this position with alligator clips until ready for shear testing. In a few experiments pieces of traprock were polished and similarly bonded together as shown in... 

Silica sand is hydrophihc and consequently attracts water to its surface. This property could lead to moisture-accelerated damage and associated stripping problems in an asphalt pavement. Antistripping additives may be required to counteract such problems. Depending on the binder and type of metal cast, the pH of spent foundry sand can vary from approximately 4-8 [87]. It has been reported that some spent foundry sands can be corrosive to metals [85]. 

Uses Emulsifier in cosmetics flotation agent corrosion inhibitor stripping agent for paints mold release agent for rubber and plastics anticaking agent in potassium fertilizers in textiles, water treatment, concrete, asphalt, ceramics, paints, metals, rubber, plastics, agric. Trade Names Armeen C Armeen CD... 

Anti-stripping agents are also used in the production of hot or warm asphalts (bituminous mixtures) in order to improve the adhesion between bitumen and hydrophilic aggregates in the presence of water. The addition of anti-stripping agent not only preserves the cohesion, stability and stiffness of the asphalts when wet but also prevents ravelling. 

Uses Defoamer for latex mtg., formulation of aq. paints and adhesives, effluent water, asphalt emulsions, PVC monomer stripping, personal care formulations Properties Opaque oily liq. sol. 5% in min. spirits, disp. in water sp.gr. 0.89 flash pt. (PMCC) > 200 F pH 5.0 100% act. 

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