Saturday, March 31, 2012

DETERMINATION OF OPTIMUM BITUMEN CONTENT

Five graphs are plotted with values of bitumen content against the value of
                        i)          Density Gb g/cm3
                        ii)         Marshall stability, S kg
                        iii)         Voids in total mix, Vv %
                        iv)        Flow value, F (0.01 mm units)
                        v)         Voids filled with bitumen, VFB%.
Let the bitumen contents corresponding to maximum density be B1, corresponding to maximum stability be B2 and that corresponding to the specified void content Vv (4.0%in the case of dense AC mix) be B3. Then the optimum bitumen content for mix design is given by:
B0 = (B1 + B2 + B3) / 3
The values of flow and VFB are found from the graphs, corresponding to bitumen content B0. All the design values of Marshall Stability, flow, voids and VFB are checked at the optimum bitumen content B0, with the specified design requirements of the mix.

RELATED FIGURES/GRAPHS ARE GIVEN IN NEXT ARTICLE : LABORATORY TEST RESULT OF MODIFIED BITUMEN

No comments:

Post a Comment