GOLLALAMMA THALLI SAI

EFFECT OF ACE GEOGRID REINFORCEMENT IN SILTY

SUBGRADE SOIL

Presented by

S.Ch.H. Reddy Mallidi, Final Year B.Tech (Civil Engineering)

SASTRA University, Thanjavur

INTRODUCTION

• Geogrids can remarkably improve soil behaviors by means of their confining effect

• Geogrid which is woven by high strength polyester yarns was used

• Laboratory investigation was carried out keeping the grid at one half and two third depths in the CBR mould

ABOUT ACE GRID

.ACE Geogrid is woven by high strength polyester (PET) yarns with various mesh sizes and specifications.Exterior of Geogrid is coated with PVC or nontoxic substance material for UV, acid, and alkali resistance and to prevent the bio-decomposition

Advantages of ACE Geogrid

.Cost and time saving Flexible .Easily handled .High creep resistance .Customized production .Friendly and ecological surface etc.

Applications of ACE Geogrid

• Residential• Industrial• Urban• Slope engineering• Traffic engineering• Waste landfill engineering• River/maritime engineering

Principle of Reinforcement

• Using the tensile properties of geosynthetic material resists stress or contains deformation in geotechnical structures

• Reinforcement may also be used to improve the performance of weak soils to support embankments or other resilient structures

EXPERIMENTAL INVESTIGATIONS (A) Grain Size Analysis (B) Liquid limit (C) Plastic limit (D) Standard proctor Test

* (E) CALIFORNIA BEARING RATIO TEST (CBR) * (F) SHEAR STRENGTH

Grain Size Analysis

S.NO IS Sieve(mm)

Weight Retained(g)

% Weight Retained

Cumulative % Weight retained

%Finer

1 4.75mm 146 14.6 14.6 85.4

2 2.36mm 102 10.2 24.8 75.2

3 1.18mm 104 10.4 35.2 64.8

4 600µ 126 12.6 47.8 52.2

5 300µ 298 29.8 77.6 22.4

6 150µ 164 16.4 94 6.0

7 75µ 42 4.2 98.2 1.8

8 PAN 18 1.8 100 0

(B) Liquid limit

Trial no 1 2 3 4

No.of blows 48 40 32 11

Tare no 2 18 3 10

Wt.of tare(g) 10 10 10 8

Wt of wet sample+tare(g) 46 20 18 24

Wt of dry sample+tare(g) 38 18 16 20Wt of water(g) 8 2 2 4

Wt of dry soil(g) 28 8 6 12

Water content % 28.57 25 33.3 33.3

(C) Plastic limit

Trail no 1 2

Tare no 2 7

Wt.of tare(g) 8 8

Wt of wet sample+tare(g) 14 14

Wt of dry sample+tare(g) 12 12

Wt of water(g) 2 2

Wt of dry soil(g) 4 4

Water content % 50 50

(D) Standard proctor Test • Dia of mould=11cm, • Height of mould=12cm, • Volume of mould=1140.39cm³, • Weight of mould without collar(w1)=2.704kg

Optimum water content of soil was found to be 12% and the same has been used for preparing CBR specimens

Description Trail 1 Trail 2 Trial 3 Trail 4Weight of mould with compacted

soil(w2)g

4124 4206 4204 4116

Weight of compacted soil g

1420 1502 1500 1412

Wet density(g/cm³)

1.245 1.317 1.315 1.238

(E) California Bearing Ratio Test (CBR)

CBR test was carried out keeping the grid at one half and one forth depth from the top of mould.

Plane CBR value of the soil = 2.1

geo grid is placed in the ½ distance

CBR value when geo grid is placed in the ½ distance of the mould = 3.13

geo grid is placed in the 1/4 distance

CBR value when geo grid is placed in the 1/4 from the top of the mould=4.18

Comparing CBR values

PLANE CBR REINFORCED

WITH GEOGRIDREDUCTION IN THICKNESS OF

SUBGRADE2.1(841mm) 3.13(752mm) 89mm

2.1(841mm) 4.18(693mm) 148mm

(F) SHEAR STRENGTH

Direct shear test was carried out keeping the grid at one half and one forth depths from the top of mould.

SHEAR STRENGTH OF THE SAMPLE WITHOUT PLACING GEO GRID: 24.475kN/m²

SHEAR STRENGTH OF THE SAMPLE AFTER PLACING OF GEO GRID: 41.67 kN/m²

Railway Foundation Reinforcement in India

Foundation Improvement in Tabasco,Mexico

CONCLUSION

Hence it can be understood that ACE geogrid can REDUCE THE TOTAL THICKNESS OF PAVEMENT and INCREASE THE SHEAR STRENGTH significantly when used as reinforcement in sub grade soils resulting in considerable economy .