Open graded friction courses

Two of the more recent innovations for using sulfur modified binders are in conjunction with recycling old asphalt pavements and the construction of open graded friction courses (OGFC). 

Cooley LA, Brown ER, Watson DE (2000) Evaluation of open-graded friction course mixtures containing cellulose fibers. Transp Res Rec 1723 19... 

The influence of highway pavement surface type on tire/pavement noise was studied (Bennert et al., 2006). It was found that the open-graded friction course (OGFC) with the hot mix GRT-modified asphalts attained the lowest noise levels. Also, the GRT-modified OGFC mixes exhibited finer aggregate gradations than the traditionally used OGFC. 

Source Reprinted from ASTM D 7064, Standard practice for open-graded friction courses (OGFC) mix design. West Conshohocken, Pennsylvania. US ASTM International, 2008. With permission ( ASTM International). 

ASTM D 6932/D 6932M. 2008. Standard guide for materials and construction of open-graded friction course plant mixtures. West Conshohocken, PA ASTM International. 

For the surface layer, in particular, the asphalts most commonly used nowadays are (a) asphalt concrete for very thin layers (AC-VTL), (b) porous asphalt (PA), (c) open-graded friction course mixture (OGFC), (d) stone mastic asphalt (SMA), (e) single or double surface dressing (S-SD or D-SD) and (f) micro-surfacing (MS). Table 10.17 gives the comparative properties/characteristics for all the abovementioned surfacing materials. 

With regard to the American practice for designing open-graded mixtures, ASTM D 7064 (2008) is used. These mixtures are recommended to be used in friction (surface) courses. Since these mixtures are similar to PA, they are described in detail in Section 5.6.2. 

Three types of RA have been used traditionally porous friction course, and gap and open graded asphalt concretes. 

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