Filled asphalt emulsions containing betaine emulsifier

A method of forming an oil-in-water asphalt emulsion comprising

• (a) forming a mixture of water, asphalt and one or more amphoteric emulsifiers having the formula
• R.sup.4 --(OC.sub.3 H.sub.6).sub.0-1 (C(O)NH(CH.sub.2).sub.1-3).sub.0-1 --N(Z.sup.1) (Z.sup.2).sub.0-1 --ZCOOX
• wherein X is --H, sodium, calcium, potassium, lithium or ammonium or an amine of the formula --N.sup.+ H(C.sub.1-20 alkyl).sub.2 or --N.sup.+ H.sub.2 (C.sub.1-20 alkyl), R.sup.4 is straight or branched alkyl or alkylene or homocyclic or heterocyclic aromatic which is optionally substituted with alkyl and contains 4 to 40 carbon atoms and 0-5 carbon-carbon double bonds, Z.sup.1 and Z.sup.2 are independently of each other C.sub.f H.sub.2f+1 or C.sub.f H.sub.2f OH, wherein f is 1 to 6, or one of Z.sup.1 and Z.sup.2 can be --ZCOOX, wherein Z is (CH.sub.2).sub.f, CH.sub.2 CH.sub.2 OCH.sub.2 CH.sub.2 or CH.sub.2 CHOHCH.sub.2 and
• (b) emulsifying said mixture whereby an emulsion is formed in which said water is the continuous phase and said asphalt is a discontinuous phase uniformly dispersed in said emulsion,
• further comprising adding particulate filler that does not chemically react with said water, asphalt and/or amphoteric emulsifiers to said mixture before, during and/or after emulsification thereof,
• wherein said emulsion is a storage-stable oil-in-water asphalt emulsion having said particulate filler uniformly distributed throughout said emulsion, which emulsion exhibits long-term phase stability.

A method of forming a continuous, highly water-impervious coating to a surface comprising (1) forming a storage-stable filled oil-in-water asphalt emulsion which exhibits long-term phase stability, said emulsion comprising

• (A) water as a continuous phase;
• (B) asphalt as a discontinuous phase uniformly dispersed in said emulsion;
• (C) particulate filler that does not chemically react with said water and said asphalt uniformly distributed throughout said emulsion;
• and
• (D) one or more amphoteric emulsifiers which are compounds of the formula
• R.sup.4 --(OC.sub.3 H.sub.6).sub.0-1 (C(O)NH(CH.sub.2).sub.1-3).sub.0-1 --N(Z.sup.1)(Z.sup.2).sub.0-1 --ZCOOX
• wherein X is --H, sodium, calcium, potassium, lithium or ammonium or an amine of the formula --N.sup.+ H(C.sub.1-20 alkyl).sub.2 or --N.sup.+ H.sub.2 (C.sub.1-20 alkyl), R.sup.4 is straight or branched alkyl or alkylene or homocyclic or heterocyclic aromatic which is optionally substituted with alkyl and contains 4 to 40 carbon atoms and 0-5 carbon-carbon double bonds, Z.sup.1 and Z.sup.2 are independently of each other C.sub.f H.sub.2f+1 OH or C.sub.f H.sub.2f OH, wherein f is 1 to 6, or one of Z.sup.1 and Z.sup.2 can be --ZCOOX, wherein Z is (CH.sub.2).sub.f, CH.sub.2 CH.sub.2 OCH.sub.2 CH.sub.2 or CH.sub.2 CHOHCH.sub.2 ;
• and
• (2) coating a surface with said asphalt emulsion.