INVESTIGATION OF A SURFACING PROBLEM

Messed up the seal? Read how to start your investigation here:

Start by getting the background quality control details (NB this is written in terms of Australian standards, and other authorities use other tests - the same concept applies irrespective of test method).
 
Aggregate Source and test results that relate specifically to your works.  
Old results are no good unless the traceability can be confirmed back to stockpiles of material that were actually used on the works.
 
Test results should include:
 
Particle Size Distribution
Flakiness Index
Los Angeles Abrasion Value
Wet / Dry Strength Variation
Water Absorption
Particle Density
All testing should have been performed in accordance with AS1141 under the guidelines of AS 2758 Part 5 Asphalt Aggregates.
 
Bitumen Source and test results that relate specifically to your works.
 These results should include:
 
Viscosity @ 60C
Viscosity @ 135C
Penetration @ 25C
Flashpoint
Matter Insoluble in Toluene
Short Term effect of heat and air
Viscosity of residue as % of original after heat and air effects
Long Term effect of Heat and Air
Density @ 15C

and I'd give some thought to doing extra tests. Wax content if it looks like the bitumen has been flowing in hot weather. If you smell diesel or tar, or you suspect contamination, then maybe GC and HPLC testing is needed. I've got a paper on reverse engineering a bleeding seal in my list of papers and another paper on tracking bitumen quality.

All testing should have been performed in accordance with AS 2341 under the requirements of Table 2 of AS2008 Residual Bitumen.
 
If it is asphalt and not a seal: it should have been in accordance with AS 2150 Hotmix Asphalt and asphalt laying should have been in accordance with AS 2734 Guide to Good Paving Practice - Asphalt.
 
Hidden secrets of top investigators 
The hidden secrets are to go and look for:
 


Thanks to Lyndon White who wrote most of this.

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Last updated 22 March 2008