Associated Asphalt‘s panic call to our offices in October 2001 sent our mobile highway repair team rushing down to the A45 in Wellingborough, Northants. Wide (20-30mm) transverse cracks required treatment prior to the completion of the new thin layer surfacing that was scheduled for later that week.
Upon inspection of the visible open surface cracking our site engineer ascertained that the underlying concrete road slab was in fact transferring severe, imposed live tensile movements upwards through to the surfacing and would, unless treated, cause the new overlay to reflect the same pattern of cracking in a short period of time.
RAB specified that the full depth of the road surfacing be removed (ie. down to the base slab) centrally over the cracking for a width of 500mm.
Road surface milled out to expose cracked concrete sub-base.
 
  RAB would then supply and fix their ‘SAMI’ hot molten compound to fill the live cracks and overlay the trench width with a 5mm thick layer, followed by a high tensile geo-grid bedded into the liquid compound. This complete system allows the live, natural ongoing movements to continue. However, their tensile and compression movements would become absorbed in the ‘SAMI’ compounds and the geo-textile would be able to safely transfer dynamic loadings over the crack widths.
RAB SAMI compounds poured into crack in 5mm layers, followed by the geo-textile grid.

 

How the RAB SAMI System Works

(click here for a super-size image of this technical drawing)
To enquire further about the SAMI System please click here to email us or phone us on 01629 814589