DISCUSSION -A FORMULA FOR THE CALCULATION OF 

 ROCK FILL DIKES 



Discussion by Mto Ro Mo McCronej Lower Mississippi Valley 

 Divisions Ctorps of Engineers 



Formulae set forth by Mro Iribarren, or appropriate modification 

 thereof s will be quite useful to shore and harbor engineers concerned 

 with sizes of stone and slopes of riprap structures for resisting wave 

 action o Presumably, the Beach Erosion Baard will correlate these data 

 with those presented in the report on "Slope Protection" presented in 

 Proceedings ASCEj June 194^8, with discussions in later months o It 

 seems pertinent to suggest that serious consideration be given to 

 developments in the use of sand asphalt mixtures for structures which 

 are to provide protection against wave action or erosion due to river 

 currents since it has been demonstrated to practicable and economical 

 to place suitably proportioned masses of hot mix by gravity under 

 water as well as in air to congeal as dense , insoluble, homogeneous, 

 concreted masses with adequate stability and toughness, highly resist- 

 ant to water and hence to attack by wave action or stream flowo 

 (Reference discussion pages 1653 and 1654? Proceedings, ASCE, December 

 1948)= 



It seems pertinent to emphasize that stnictures for protection 

 against wave action or scour due to stream flow preferably should 

 be homogeneous non-erosible monoliths rather than heterogeneous 

 masses of riprap consisting of discrete aggregates even if rock sizes 

 are adequate o Where such structures are sited on sand, it is ob- 

 viously desirable that the sand, the nearest and cheapest material, 

 be used for construction o Developments in the use of hot sand as- 

 phalt mixtures in large mass demonstrate the feasibility of combining 

 sand and asphalt suitably proportioned at appropriate temperatures 

 for gravity placement under water or in air to congeal substantially 

 as a homogeneous monolitho One such monolilh , about 1,800 tons, is 

 pictured on page 1654 of the December proceedings o Another, upward 

 of 6,000 tons, placed (Fall 1948) as a wing dam in the Mississippi 

 River (Mile 468 AHP), provides protection at the lower end of the 

 Filter Bend revetmento 



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