Use of lignin solution in the road

structure to increase the bearing capacity

of forest truck roads

Jan Bjerketvedt

FORMEC 2016 – From Theory to Practice: Challenges for Forest Engineering

September 4 – 7, 2016, Warsaw, Poland

0

10000

20000

30000

40000

50000

60000

19

49

19

51

19

53

19

55

19

57

19

59

19

61

19

63

19

65

19

67

19

69

19

71

19

73

19

75

19

77

19

79

19

81

19

83

19

85

19

87

19

89

19

91

19

93

19

95

19

97

19

99

20

01

20

03

20

05

20

07

20

09

20

11

New roads

Rebuilt roads

Larger timber trucks

Transport through the whole year

Roads build with local materials

Building of forest truck roads, acc. km

Climatic changes

42.000 km -10.000 km 32.000 km older than 25 years

Rebuilding cost: 270 NOK/m (30 €)

8,64 bill. NOK ( 1 b. €)

4 meters

25 cm

25 cm top layer of crushed rock reduce the road width about 30 cm on each side 35 cm top layer of gravel reduce the width 2x50 cm The Norwegian Forest Road Standard increased the minimum road width from 3.5 meters to 4.0 meters in 1997

Reinforce and widen

Reinforce without widening?

Add bearing capacity reinforcing materials

or solutions?

The common use of lignin (or lignosulfonate) solution is on the road surface as a dust suppressant and road stabilizer; it binds soil particles to provide a solid, hardwearing surface. Long term experiences from the Norwegian Public Road Administration indicated that the treatment also resulted in an increased bearing capacity.

This study is aimed at measuring the effect on bearing capacity of applying lignin (Norwegian trademark Dustex) to the top/base layer (upper 20 cm) on existing forest roads and if this is an economically viable alternative to traditional methods.

Dustex is biodegradable and has no environmental restrictions.

4

18.09.2016

1

2

18.09.2016

What have we done?

1. Measure bearing capacity 1, before treatment, - June 2013 2. Crushing and Dustex-treatment, - June 2013 3. Measure bearing capacity 2, after 1 year, - July 2014 4. Measure bearing capacity 3, autumn rain, - October 2014 5. Measure bearing capacity 4, after 2 years, - June 2015

18.09.2016

Dynatest 8002

18.09.2016

18.09.2016 9

Built-in FWD, Pri 2509, from SWECO (was Grontmij)

18.09.2016

Bearing capacity was registered for every 50 meter on the right road side. On the retour the starting point was moved 25 meters, so that the measurements from the left road side was placed between the ones on the right side. The roads are mapped with measurements for every 25 meters, but on alternating road side. General impression: Large variations between neighboring points, road side (cut/fill) and road sections. Should not be a surprice for an old forest road built with local moraine materials, but….

18.09.2016

Road 1, Summer 2013, Before treatment

18.09.2016

18.09.2016

Spraying about 8 l/m2

18.09.2016

18.09.2016

18.09.2016 16

0

2

4

6

8

10

12

14

16

18

20

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Før_1306

Som1_1407

18.09.2016 17

0

2

4

6

8

10

12

14

16

18

20

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Før_1306

Som1_1407

Høst_1410

18.09.2016 18

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Før_1306

Som1_1407

Høst_1410

Som2_1506

18.09.2016 19

0,00

5,00

10,00

15,00

20,00

25,00

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Før_1306

Som1_1407

Høst_1410

Som2_1506

0,00

5,00

10,00

15,00

20,00

1 2 3 4 5 6 7 8 9

Før_1306

Som1_1407

Høst_1410

Som2_1506

ROAD 1

18.09.2016 20

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8

Før_1306

Som1_1407

Høst_1410

Som2_1506

0

5

10

15

20

25

30

10 11 12 13 14 15 16 17 18 19 20 21

Før_1306

Som1_1407

Høst_1410

Som2_1506

ROAD 2

18.09.2016 21

0

50

100

150

200

250

Før_1306 Som1_1407 Høst_1410 Som2_1506

Ubehandlet

Behandlet

% ROAD 1

Untreated Dustex treated

18.09.2016 22

0

20

40

60

80

100

120

140

160

180

Før_1306 Som1_1407 Høst_1410 Som2_1506

Ubehandlet

Behandlet

ROAD 2

Untreated Dustex treated

18.09.2016 23

Untreated Dustex-treated

Road 1 Road 2

Untreated Dustex-treated

- 3 t / - 19 % - 2.4 t / - 15 % + 2 t / + 17 %

+ 1 t / + 9 %

The Norwegian Forest Road Standard requirement is 10 tons axel load

4 meters

25 cm

25 cm top layer of crushed rock reduce the road width about 30 cm on each side 35 cm top layer of gravel reduce the width 2x50 cm

25 cm top layer, 4 m width is 1 m3 or 1,5 tonn materiale per meter road 1,5 t a 100 NOK = 150 NOK/m road + transport + widening = ca 250-300 NOK/m road (28-33 €)

Reinforce and widen

Dustex-treatment: ca 160-200 NOK/m road (18-22 €)

18.09.2016

Conclusion

• Clear positive effekt of the Dustex-treatment for the bearing capacity in wet/rainy periods, - in short term

• Whether this treatment is an economically viable alternative to

traditional methods in the long term or not, still remains an unanswered question. The lignin is compostable and the duration of the measured increase in bearing capacity under wet conditions is uncertain.

• The Norwegian Institute of Bioeconomy Research (NIBIO) aims to follow up these test roads in the future (2018? After 5 years?)

Thank you!

26