Quality control during laying slurry surfacing

6 Quality control during laying slurry surfacing 

For the determination of the residual bitumen content and aggregate gradation, the representative samples are taken from the slurry machine, at the discharge point, according to CEN EN 12274-1. 

The determination of the residual bitumen content is carried out according to CEN EN 12274-2 (2003) followed by CEN EN 12697-1 (2012). Alternatively, after the mixture has been dried completely, the determination of the residual bitumen content may be carried out in accordance to ASTM D 2172 (2011) or AASHTO T 164 (2013). The acceptable tolerances from the target mix, according to ISSA A105 (2010), for the residual bitumen content should be 1.0% by mass of dry aggregate. 

The determination of the aggregate gradation after extraction is carried out mechanically as per hot asphalts, according to CEN EN 933-1 (2012), ASTM C 136 (2006) or AASHTO T 27 (2011) and ASTM C 117 (2013) or AASHTO T 11 (2009). The tolerance ranges from the target gradation should be as those given in Table 6.4. 

The frequency of sampling for determination of residual bitumen content and aggregate gradation is recommended to be at least one every 5000 m.  

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