General Review on the .Application of Aspha lt M ixtures 



For hydraulic works the asphaltic bitumen is mostly used in a 

 mixture, in which the percentage of the expensive asphaltic bitumen 

 is kept as low as possible. The other materials such as the filler 

 (partly), sand, gravel and broken stone are natural products, the 

 gradation of which greatly influences the quality of the mixture. 

 Therefore, to efficiently obtain reliable results, laboratory con- 

 trol and information are of great value . 



In working with asphalt mixtures, one should keep the 

 temperature as high as possible until the job is reached. Care 

 should be taken that no superheating occurs , since then the 

 asphaltic bitumen will be cracked s which means that free carbon is 

 formed, changing the mechanical properties unfavorably. 



In many instances where hydraulic works are constructed the 

 water can be retained temporarily so that the asphalt mixture can 

 be applied on a dry base. In other areas subject to tidal- and 

 wave-action it often occurs that the job must be completed within 

 a short period of time and the mixture has to be applied to a wet 

 base or even under water. In the latter case one cannot depend 

 on adhesion and special measures must be taken in order to carry 

 the asphalt mixture into place at the required temperature. The 

 recent experiments in the 1st kerosene-harbour at Rotterdam, 

 where a plastic mixture was carried to its destination through 

 isolated tubes, indicated that it is quite possible that this 

 material can even be applied underwater. Certainly, the last 

 word regarding these problems has not been said yet, but by 

 proper cooperation between the research institutes and those who 

 design and execute hydraulic works where bitumen is being used, 

 the solution of these problems can definitely be found. 



Cold and Hot Asphalt 



Asphaltic bitumen is used in hydraulic works as cold asphalt 

 and as hot asphalt. 



Hot asphalt may be used in; 



1. Permeable works. 



a. by penetration with pure asphaltic bitumen 



b. by penetration with asphalt mastic 



c. by sheeting with bituminous sand 



2 . Impermeable works . 



a. by surface-treatment s with pure asphaltic bitumen 



b. by sheeting with asphalt mortar (sand asphalt) 



c. by sheeting with asphalt concrete 



d. by grouting with pouring asphalt. 



