1) Stockpile or cold bin aggregate sampling for combined gradation
(to control the aggregate overflow in the hot bin)
2) Hot bin aggregate sampling- individual & combined gradation, JMF, sp gr of each aggregate size & Gsb calculation, and check with 0.45 power chart
3) Marshall batch preparation (1200-1260gm aggregate), take Pb according to spec lower limit and increase by 0.5%, and cast the mold accordingly and measure the thickness of specimens
4) Determination of the Sp Gr of the compacted mix, Gmb
5) Determination of the Max Theo Sp Gr of paving mix, Gmm
6) Air voids calculation
7) VMA & VFA calculation
8) Stability and Flow checking, Stability correction as per volume or thickness of the Marshall samples/specimens
9) Check the ratio of Stability and Flow
10) Produce the graph (Va, VMA, VFA, Gmb, Stability, Flow, & Marshall Ratio vs. Pb)
11) Take the final bitumen% (Pb) from Va vs. Pb graph at 4% Air Voids (4% is median of air voids that specified in the spec, 3%-5%) and cut all other graphs according to optimum bitumen content
12) Prepare the final design batch sheet
13) Trial should be performed according to the tolerance limit of binder (3 sets Marshall mold) and check the other properties of design according to OBC tolerance
14) Check the retained stability at OBC% (2 sets one is for 24hrs @ 60°C water bath and one set for 4hrs @ 60°C air bath, if it is specified in the spec)
15) Refusal density test of asphalt @ 300, 400, & 500 blows (air voids vs. blows graph) using OBC or OBC+0.2, the road will start failing if air voids less than 2%.
NB: Prepare viscosity chart @ two temperatures (such as 140°F & 270°F) and check the required temperature of mixing and compaction as per viscosity-temperature line (Range for Compaction 0.28+/-0.03 Pa-s and Mixing 0.17+/-0.02 Pa-s) before preparing Marshall mold.