NESTEM

NESTEM is a geotextile/geogrid material for use in reinforced earthwork and is fabricated using a continuous impregnation process (Fig. 3.56). Glass fibers are soaked in a corrosion-resistant thermosetting resin system such as a vinylester or polyester to form a grid-like structure without significant dimensions in the thickness direction.


Fig. 3.56. Schematic of the NESTEM process.

The material, which has high tensile strength and stiffness and is extremely light, has excellent chemical resistance and has been shown to have extremely good long-term potential under harsh field conditions. Figure 3.57 shows a schematic of the layout and grid spacing of the material. Standard specifications for the five commonly available varieties are listed in Table 3.19.


Fig. 3.57. Schematic layout of NESTEM structure.

Table 3.19
Specification for Standard Grades of Glass Fiber Reinforced NESTEM Elements

Specification

  

Grade of NESTEM

  
 

GB5

GB8

GB10

GB15

GB22

Weight (g/m2)

260

420

510

850

960

Tensile Strength (Ton/m): L

5

8

10

15

20

T

2.5

4

5

7.5

10


Key: L=Longitudinal; T=Transverse

The glass fiber reinforced thermoset resin based composite has a fiber volume fraction of 50% and generally contains a black pigment or carbon black to increase UV resistance. NESTEM is available in rolls of 30 m length and 1 m width. As seen in Fig. 3.58, NESTEM can be used to reinforce the road subgrade, where it prevents rutting of the road surface, constrains irregular settlement of soft ground and prevents cracking of the road.



Fig. 3.58. Use of NESTEM in road subgrades.



Fig. 3.59. Use of NESTEM in road widening.

NESTEM is also used for stabilizing embankments during the widening of roads, where space constraints can result in the use of very steep slopes (Fig. 3.59). Its use in embankment slopes and reinforced walls is shown in Fig. 3.60. It is easy to place and is fairly easily overgrown by vegetation. It serves as an anchor for strata and offers sufficient frictional resistance between the soil and the layers of NESTEM to stabilize surrounding soil strata/layers.



Fig. 3.60. Use of NESTEM in embankment slopes and reinforced soil walls.

Table 3.20 represents a partial list of projects using NESTEM conducted from 1989 to 1993.

Table 3.20
Examples of Projects using NESTEM

No

Date

Project Name

Project Site

Client

Specification

1

10/1989

Nippondenso Co., Ltd. Nukata Test Course

Nukatabe County, Aichi Prefecture

Nippondenso Co., Ltd.

Reinforced embankment, Slope 1:1.8, H = 12 m

2

12/1989

The Tokyo Electric Power Co., Ltd., Kashiwazaki Atomic Power Plant

Kashiwazaki City, Niigata Prefecture

The Tokyo Electric Power Co., Ltd.

Reinforced soil wall

Slope 1:0:3; H = 3 m

3

12/1989

Public Works Research Institutes, Ministry of Construction, reinforced retaining wall experiment

Tsukuba City,

Ibaraki Prefecture

Public Works Research Institute, Ministry of Construction

Reinforced soil wall

Slope 1:0:1; H = 5 m

4

5/1990

ITJ Second Stage Earthworks

Yamaguchi City, Yamaguchi Prefecture

ITJ Co., Ltd.

Reinforced soil wall

Slope 1:0:3; H = 7 m

5

5/1990

Daini Den Den Aomori Route, Tsugaru Station

Tsugaru County, Aomori Prefecture

Daini Den Den Co., Ltd.

Reinforced soil wall

Slope 1:0:2; H = 3 m

6

5/1990

Tokin Lakeside Hill, First Regulating Reservoir

Tokin City, Chiba Prefecture

Toso Urban Development Co., Ltd.

Reinforced soil wall

Slope 1:1:0; H = 4.5 m

7

7/1990

Arigawa Dam Gensekiyama Covering Works

Setana County, Hokkaido

Hokkaido Development Agency

Reinforced soil wall

Slope 1:0:5; H = 5 m

8

9/1990

KDD Ouchibata Relay Station

Yamaguchi City, Yamaguchi Prefecture

KDD Co., Ltd.

Reinforced soil wall

Slope 1:0:3; H = 8 m

9

9/1990

Tokin Lakeside Hill Second Regulating Reservoir

Tokin City, Ibaraki Prefecture

Toso Urban Development Co., Ltd.

Reinforced soil wall

Slope 1:1:0; H = 4.5 m

10

10/1990

Izu Amagi Earthworks

Ito City, Shizuoka Prefecture

Mori Residence

Reinforced soil foundation

11

12/1990

Nosu Street Widening Works

Hachioji City, Tokyo Prefecture

Tama Town Development Office, Tokyo Prefecture

Reinforced soil wall

Slope 1:0:2; H = 2 m

12

2/1991

Ninomiya Town, Ishiki Nakazato Land Readjustment Project

Ninomiya Town, Kanagawa Prefecture

Ninomiya Town, Ishiki Nakazato Land Adjustment Association

Reinforced soil wall

Slope 1:1:0; H = 5.5 m

13

4/1991

Narita New Marketing Center

Narita City, Chiba Prefecture

Sanki Co., Ltd.

Reinforced soil wall

Slope 1:0:3; H = 6.5 m

14

4/1991

Izu Amagi Earthworks

Ito City, Shizuoka Prefecture

Mori Residence

Reinforced soil foundation

Reinforced soil wall

Slope 1:0:5; H = 5 m

15

5/1991

Tokiwa Highway

Niizu City, Niigata Prefecture

Japan Highway Public Corp.

Reinforced base course (temporary road); L = 50 m

16

7/1991

Natori Multi-Purpose Gym

Natori City,

Miyagi Prefecture

The Tohoku Electric Power Co., Inc.

Reinforced embankment

Slope 1:1:5; H = 23 m

17

7/1991

Hakusan Senyo Kougen Skiing Ground

Ishikawa County, Ishikawa Prefecture

Hakusan Lake Highland Co., Ltd.

Reinforced soil wall

Slope 1:0:3; H = 8 m

Table 3.20 (cont.)
Examples of Projects using NESTEM

No

Date

Project Name

Project Site

Client

Specification

18

7/1991

Daini Den Den Higashi Kanasaka Second Route, Shimizudera Relay Station

Higashi Chikuma County, Nagano Prefecture

Daini Den Den Co., Ltd.

Reinforced soil wall

Slope 1:0:5; H = 7.5 m

19

12/1991

Tamura, Okiyado Land Readjustment Project

Tsuchiura City, Ibaraki Prefecture

Ibaraki Prefecture

Reinforced base course

20

1/1992

Itabashi #5 & #6 Embankment & Revetment Works

Itabashi Town, Tokyo Prefecture

Arakawakaryu Work Office, Ministry of Construction

Reinforced soil wall

Slope 1:0:5; H = 3 m

21

2/1992

ITJ Yamaguchi-Miyazaki Microwave Route, Hatakura Wireless Station Project

Nakatano Town, Miyazaki Prefecture

ITJ CO., Ltd.

Reinforced soil wall

Slope 1:0:5; H = 11.5 m

22

3/1992

Tokiwa Highway Niizu Works

Niizu City, Niigata Prefecture

Japan Highway Public Corporation

Reinforced base course (temporary road) L = 632 m

23

4/1992

#6 Embankment & Revetment Works

Itabashi Town, Tokyo Prefecture

Arakawakaryu Work Office, Ministry of Construction

Reinforced soil wall

Slope 1:0:5; H = 3 m

24

4/1992

Aizu Nanbu Agricultural Irrigation Project, Okawa Driving Channel Improvement Works

Hongo Town, Onuma County, Fukushima Prefecture

Aizu Irrigation Work Office, Tohoku Regional Agricultural Administration

Reinforced soil wall

Slope 1:0:5; H = 5.6 m

25

5/1992

ITJ Yamaguchi-Miyazaki Microwave Route, Kotsikiyama Wireless Station Project

Ogori Town, Yoshiki County, Yamaguchi Prefecture

ITJ CO., Ltd.

Reinforced soil wall

Slope 1:0:3, 0.5; H = 8 m

26

7/1992

Hachinohe Sawazato Road Improvement Works

Hachinohe City, Aomori Prefecture

Hachinohe Town Development Office, Industrial Relocation and Coal Production Areas Promotion Corp.

Reinforced soil wall

Slope 1:0:5; H = 7.5 m

27

12/1992

Nihon Shokusei Central Research Institute

Tsuyama City, Kagawa Prefecture

Nihon Shokusei Co., Ltd.

Reinforced soil wall

Slope 1:0:5; H = 6 m

28

1/1993

Takamatsu Airport Vestige Land Works

Takamatsu City, Kagawa Prefecture

Kagawa

Prefecture

Reinforced base course

29

3/1993

Miyaoku Dam Temporary Road Works

Ouda Town, Nara Prefecture

Nara Prefecture

Reinforced soil wall

Slope 1:0:1; H = 3.5 m


Published: November 1998; WTEC Hyper-Librarian