Basics knowledge regarding road work

Steps sequence for filling of road with different materials:

1)Subgrade  (minimum thickness required-500mm)

2)GSB(Granular sub base -150mm thickness required)

3)WMM(wet mix macadam-150mm thickness required)

4)BM(Bituminous macadam-36mm)

5)DBM(Dense bitumen macadam-Thickness variable -50 to 100mm)

6)BC(Bituminous concrete -Thickness variable(40mm to 50mm) 

• Between WMM and BM we provide prome coat as directed by engineer-in charge with theoretical consumption of 06kg/sqm.
• After BM  in all levels of materials we provide tack coat with theoretical consumption of 0.2kg/sqm as per directed by engineer in charge.

At our present via-duct elevated flyover project in new Delhi we consider following density of each materials-

• Subgrade-1.8 gm/cc
• GSB-1.89 gm/cc
• WMM-2.1 gm/cc
• BM-2.2 gm/cc
• DBM-2.3 gm/cc
• BC-2.36 gm/cc   

Gradation chart for the materials used for road work as per the Morth:-

Sieve size	BM	DBM	BC
45 mm
37.5mm		100
26.5mm	100	90-100	100
19mm	90-100	71-95	79-100
13.2mm	56-88	56-80	59-79
9.5mm			52-72
4.5mm	16-36	38-54	35-55
2.36mm	04-19	28-42	28-44
1.18mm			20-34
600micron			15-27
300micron	02-10	07-21	10 - 20
150micron			5 - 13
75micron	0- 8	2 - 8	2 - 8
PAN

Sieve size	GSB	WMM
75 mm
53 mm
45mm
26.5mm
22.4mm
11.20 mm
9.5mm
4.75mm
2.36mm
0.85mm
0.6mm
0.425mm
0.075mm

Sieve size	WMM
	Passing limits
53mm	100
45mm	95-100
22.4mm	60-80
11.2mm	40-60
4.75mm	25-40
2.36mm	15-30
600 micron	8 - 22
75 micron	0-5
Impact value	30 max
water absorption	2 max
Los angeles abration value	40.0 max
plasticity index	6 max

GRADING FOR GRANULAR SUB-BASE MATERIALS
Is sieve Designation	Percent by weight passing the IS Sieve
	grading I	grading II	grading III	grading IV	grading V	grading VI
75	100	-	-	-	100	-
53	80-100	100	100	100	80-100	100
26.5	55-90	70-100	55-75	50-80	55-90	75-100
9.5	35-65	50-80	-	-	35-65	55-75
4.75	25-55	40-65	10- 30	15-35	25-50	30-55
2.36	20-40	30-50	-	-	10- 20	10- 25
0.85	-	-	-	-	02- 10	-
0.425	10- 15	10- 15	-	-	0-5	0-8
0.075	<5	<5	<5	<5	-	0-3

Please be noted the above mention sieve size are sufficient enough for the analysis of Gradation for all zone as per Morth (ministry of road transport and highway).

Regarding percentage passing of the materials refer the code or Morth .
Grading zone is decided by the engineer in-change as the site condition of that zone .

Regarding any query please mail me or post the comment on my blog