73 since the ITS value of 3 CR was more close to the ITS value of 0CR even after softening
temperature at 40
o
C compared with two others. Besides, the ITS value of two others percentage of crumb rubber was reduced drastically with the increasing of temperature.
4.2.8 Unconfined Compressive Strength UCS Test
Unconfined Compressive Strength Test UCS is used to determine the resistance to permanent deformation of bituminous mixtures and loads. It was conducted by applying a
static load to a specimen using OBC and then measuring the maximum load. This test used to determine the permanent deformation of normal and modified asphalt mixtures.
In the context of this research, the UCS test were conducted for 0, 3, 4 and 5 crumb rubber and 30
o
C, 40
o
C and 60
o
C for temperature. The result of UCS 0 is presented in Table 4.15.
In terms of UCS, the formula of the calculation can be seen in frmula 2.13. The result was the average of UCS sample A, B and C. The detail calculation sample of UCS at 30
o
C is as follow:
UCS = UCS Sample A =
= 6805.272727 UCS Sample B =
= 6143.454545 UCS Sample C =
= 5747.636364 Average of UCS =
= 6276.454545 UCS at 40
o
C is as follow: UCS =
UCS Sample A = = 4842.727273
UCS Sample B = = 3654
UCS Sample C = = 3340.909091
Average of UCS = 4091.81
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74 UCS at 60
o
C is as follow: UCS =
UCS Sample A = = 1965.0909
UCS Sample B = = 4029.45
UCS Sample C = = 3029.0909
Average of UCS = = 2497.0909
Table 4.15. Comparison of UCS Test at OBC at 30 , 40 And 60
AC type OBC
Load KPa 30˚C Load KPa 40˚C Load KPa 60˚C
without CR 5.60
6276.45 4091.81
2497.09
with CR 3 5.485
3337,09 2211,36
1443,27
with CR 4 5.55
2012,18 2639,00
1399,36
with CR 5 5.425
2229,81 1506,90
496,36 In line with the result of Table 4.15, the description of UCS is presented in Figure 4.36.
Figure 4.36 UCS
From the figure 4.36 it is clear that asphalt concrete without crumb rubber showed the far less prone to deform against temperature in compared with asphalt concrete with crumb rubber in
this study. As the UCS value of asphalt concrete without crumb rubber is larger than asphalt concrete with crumb rubber at different temperature. However, among three different
y = -119,37x + 9461,3 R² = 0,9236
y = -59,596x + 4913 R² = 0,9134
y = -26,364x + 3159,3 R² = 0,4221
y = -56,745x + 3870 R² = 0,9911
1000 2000
3000 4000
5000 6000
7000
10 20
30 40
50 60
70
UCS
Temperature
3 4
5 Linear 0
Linear 3 Linear 4
Linear 5
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75 percentage of crumb rubber, asphalt concrete with 3 CR showed the most decent result
since the UCS value of 3 CR was more close to the UCS value of 0 CR, except 4 crumb rubber at 40
o
C, even after softening temperature at 40
o
C compared to two others. Moreover, the UCS value of two others percentage of crumb rubber was declined
dramatically, except 4 crumb rubber at 40
o
C, with the increasing of temperature. The inconsistency of 4 CR might be happed due to the influence of softening point on
deformation resistant properties of asphalt concrete at optimum crumb rubber percentage.
4.2.9 Indirect Tensile Stiffness Modulus Test ITSM
