Mix design of OGFC

The mix design of the OGFC mixture, in accordance to ASTM D 7064 (2008), after selecting the constituent materials consists of the following stages  

For each trial aggregate grading, binder content between 6.0% and 6.5% by mass of bituminous mixture is initially selected. When using modified bitumen, higher binder contents should be selected. 

For a better performance of the OGFC mixture, there should be stone-on-stone contact in the coarse aggregate skeleton (all coarse aggregate is retained on the 4.75 mm sieve). 

The condition for stone-on-stone contact within an OGFC mixture is defined as the point at which the per cent of voids of the compacted mixture is less than the voids in the coarse aggregate (VGA) in the dry-rodded test. The dry-rodded test is carried out in accordance to ASTM C 29/C 29M (2009) from which the VCAo, ( is determined using the following equation  

Using the results of the abovementioned parameters, the void content (V ) and the VGA of the compacted mix (VCAmix) are determined using the following equations  

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