Case Studies  
Santos Container Terminal, Brazil (www.staff.ncl.ac.uk/john.knapton/Santos.htm)  
   
John Knapton has been working with Sao Paulo consulting engineers Maubertec designing the Santos Container Terminal extension. The original terminal was surfaced with 2.4m x 2.4m reinforced concrete raft units, which have failed as a result of the heavy loads applied by front lift trucks handling 40ft containers. Also, the ground has consolidated differentially so the drainage system is no longer working and ponding occurs such that containers are often standing in deep water - see picture below.  
   
 
   
The 150,000 m2 extension is also constructed over ground which will consolidate. In order to avoid the ponding problem, the pavement has been designed to be fully permeable. It comprises concrete block paving with unusually large spacers to allow a 6mm gap around each paver. The pavers are bedded on 6mm grit and the same material is used in the joints. Tests have shown that all but the heaviest showers percolate through the joints immediately. A cleaning regime has been specified to avoid joint clogging.
  
   
 
   
The picture below shows a typical paver. The semi-circular spacers were developed in collaboration with Maubertec and a Sao Paulo paver manufacturer, Glasser, who sought advice from their production plant supplier, Besser of the US.  
   
 
   
The picture below illustrates the joints prior to sand filling. The rectangular pavers of dimensions 200mm x 100mm x 80mm were laid to herringbone pattern. This has been found to be a cost effective surfacing system capable of dealing with the heaviest container handling plant and with container corner castings. At Santos, containers are to be stacked up to 4 high. The equivalent wheel loads from front lift trucks and transtainers exceed 400kN. The pavement base comprises 550mm thickness of no fines concrete with a strength of 10 N/mm2. The material has been designed to allow the free passage of water. The sub-base comprises 300mm crushed rock which also allows the passage of water. The underlying subgrade comprises fill sand material which was used as surcharge for several months prior to pavement construction.  
   
 
   
The pavers have a compressive strength of over 40 N/mm2 and have a surface which has been designed to avoid durability and abrasion problems.