Cold Asphalt 



This material is liquid at normal temperatures as a result of 

 the addition of certain volatile components which evaporate and thus 

 cause the mixture to stiffen gradually. Therefore, as a rule this 

 material cannot be used under water or in thick layers as it remains 

 soft. It would be worth while to improve the quality of this pro- 

 duct, because it may prove of great value where hot asphalt cannot 

 be used or where repairs must be carried out. Gold asphalt was 

 used in 1936 at a trial section on the outer slope of the north 

 east polder dike near Urk. 



Gold asphalt grouting containing 16$ of asphalt emulsion, 25% 

 of cement, 53$ of sand and 6% of water was applied at normal 

 Amsterdam level (N.A.P.). On each square meter of the basalt stone 

 slope protection 19 kg of grouting material containing 3 kg of 

 asphalt emulsion were used. This grouting was often submerged and 

 almost constantly subject to wave action and has gradually vanished. 



Hot b; sphalt 



This product has been used in various compositions both below 

 and above the water surface. 



To apply thin layers (surface treatment with pure asphaltic 

 bitumen or asphalt mastic) above water, a dry and dust free base 

 is essential for good adhesion. For thick layers (sheeting with 

 bituminous sand, asphalt mortar or asphalt concrete) a stable 

 mixture is required, which often should be elastic as well. 



On a wet base or under water there will never be any ad- 

 hesion between the base and the bituminous material and therefore 

 the mixture should be carried to its destination in such a way 

 that the internal heat is preserved as long as possible. This 

 can be achieved by applying the material in solid masses of sub- 

 stantial size, for instance by the aid of clamshells, shoots or 

 isolated tubes. Thus, even under water the masses will stick 

 together where they touch, because the surfaces which cooled 

 will be reheated by the radiation from the centre. Thanks to 

 this phenomenon asphalt grouting may penetrate deeply (1 to 1.5m 



under water). This is necessary, not only to envelop the 

 stone in order to anchor it safely to its base, but also to fill 

 the cavities. In works along the seashore this is imperative 

 in order to insure that the wave and groundwater action does not 

 result in internal water and air pressures which may have a 

 disastrous effect. If the voids between the stones are too small, 

 the bitumen or the mixture cools off too rapidly and there will 

 be little penetration, resulting in unsound work. Therefore, the 

 kind of works and the forces to be resisted determine to what 

 extent the cavities should be filled. Especially in sea-work one 

 should be on the alert against being penny-wise and pound-foolish. 



28 



