TEST PROGRAM
In this chapter, a case study of application of coir geotextile for increasing the CBR value has been presented. This case study is of soil in Assam, India. Assam is a state of India. In this case study attempts were made to increase the CBR value of black cotton soil in Assam using coir geotextile. A number of CBR tests are conducted (both soaked and unsoaked conditions) using samples consisting of soil only and soil with layer of coir mat at different position from the top surface. CBR tests are carried out in different sizes of molds to find out the effect of confinement. The results show that the CBR value of the coir mat reinforced subgrade when soaked shows nearly twice the CBR value of the unreinforced (i.e. without the …show more content…
From Table 5 it is observed that the maximum CBR values are obtained for position of coir mat at 1cm. The CBR values then decrease for the coir mat position at 2cm and 3.0cm and at 4.0cm. For all types molds CBR value for reinforcement at 4.0cm depth is nearly the same as for unreinforced soil. Thus, it is concluded that lowering the position of coir mat will have reduced effect on increase in CBR values of soil. The best position is near the top surface. This result is justified with the following explanation. The reason for higher CBR values for the position of coir mat at 1.0cm may be justified in two ways. First the presence of coir mat at 1 cm depth has provided maximum confinement to granular subgrade soil used in CBR mold than other position of coir mat. So, the CBR value observed is found to be highest (Baruah, …show more content…
3 13.6 6.2 6.0 4.9 4.8
4 9.1 5.8 5.5 4.7 4.6
Soaked
No Coir mat 4.5 2.4 3.1 2.5
1 8.9 7.1 5.9 5.0
2 6.6 5.9 4.8 4.4
3 6.1 4.5 4.2 4.1
4 5.1 4.1 3.8 3.1
SYMBOLS
d = Plunger diameter of CBR test = 5cm
D= Diameter of mold
D/d= α = Field CBR q = applied stress at the surface = stress generated by CBR mold during test at the surface in present case pv = stress at a depth of z below the center of a circular area of radius R
R = radius of CBR plunger = 2.5cm z = depth of coir mat = 1, 2,3,4 cm ds = Depth of soil layer where stress is calculated (cm)
% s= Stress developed at levels = pv /q in % (% of applied stress at surface)
CBRs = Soaked CBR cu = uniformity coefficient cc = coefficient of curvature k = Coefficient of permeability
OMC = Optimum moisture content
MDD: Maximum dry density
In this chapter, a case study of application of coir geotextile for increasing the CBR value has been presented. This case study is of soil in Assam, India. Assam is a state of India. In this case study attempts were made to increase the CBR value of black cotton soil in Assam using coir geotextile. A number of CBR tests are conducted (both soaked and unsoaked conditions) using samples consisting of soil only and soil with layer of coir mat at different position from the top surface. CBR tests are carried out in different sizes of molds to find out the effect of confinement. The results show that the CBR value of the coir mat reinforced subgrade when soaked shows nearly twice the CBR value of the unreinforced (i.e. without the …show more content…
From Table 5 it is observed that the maximum CBR values are obtained for position of coir mat at 1cm. The CBR values then decrease for the coir mat position at 2cm and 3.0cm and at 4.0cm. For all types molds CBR value for reinforcement at 4.0cm depth is nearly the same as for unreinforced soil. Thus, it is concluded that lowering the position of coir mat will have reduced effect on increase in CBR values of soil. The best position is near the top surface. This result is justified with the following explanation. The reason for higher CBR values for the position of coir mat at 1.0cm may be justified in two ways. First the presence of coir mat at 1 cm depth has provided maximum confinement to granular subgrade soil used in CBR mold than other position of coir mat. So, the CBR value observed is found to be highest (Baruah, …show more content…
3 13.6 6.2 6.0 4.9 4.8
4 9.1 5.8 5.5 4.7 4.6
Soaked
No Coir mat 4.5 2.4 3.1 2.5
1 8.9 7.1 5.9 5.0
2 6.6 5.9 4.8 4.4
3 6.1 4.5 4.2 4.1
4 5.1 4.1 3.8 3.1
SYMBOLS
d = Plunger diameter of CBR test = 5cm
D= Diameter of mold
D/d= α = Field CBR q = applied stress at the surface = stress generated by CBR mold during test at the surface in present case pv = stress at a depth of z below the center of a circular area of radius R
R = radius of CBR plunger = 2.5cm z = depth of coir mat = 1, 2,3,4 cm ds = Depth of soil layer where stress is calculated (cm)
% s= Stress developed at levels = pv /q in % (% of applied stress at surface)
CBRs = Soaked CBR cu = uniformity coefficient cc = coefficient of curvature k = Coefficient of permeability
OMC = Optimum moisture content
MDD: Maximum dry density