PSI - Issue 70

Vinod Kumar et al. / Procedia Structural Integrity 70 (2025) 303–310

307

3. Results and Discussion The test result of the UCS test on LS mixed with BD and cement, stress-strain behavior, and UCS of the mix were considered. As mentioned above, the A1 series of tests was conducted on the LS alone. The purpose of conducting a test on LS alone was to keep its result as a reference to evaluate the impact of admixture on the strength behavior of soil. The UCS of LS alone was found to be 205.9 kPa. In the following section, the cement and BD impact of individual admixtures on the strength behavior of LS and the combined impact of both admixtures are investigated. 3.1. Behavior of Soil mixed with cement As mentioned earlier, the A2 tests were conducted on the soil mixed with the cement. Fig. 3 shows the stress strain behavior of soil mixed with cement with different contents after CP of 7 days. It can be observed that the peak strength of the soil increases with the increase in the cement content. It can also be observed that the stress-strain curve slope increases with the increase in cement content. It shows that the UCS of soil increases with cement content, and the stiffness of the soil also increases with an increase in the cement content. Cement mobilizes the cementitious behavior, which causes soil particles to resist movement under loading conditions. Further, the variation of UCS of soil with different cement content is presented in Fig. 4. The UCS of soil at 2%, 4%, and 6% cement content was found to be 377.08 kPa, 480.6 kPa, and 572.16 kPa, respectively. From this, the improvement factor can be evaluated. The improvement factor (IF) indicates the ratio of the UCS of the mix to the UCS of the soil alone. So, for the soil with 6% cement content, a value of 2.7 was found, indicating that a 2.7 times improvement in UCS can be obtained from including 6% cement. The impact of CP on the UCS of soil can be observed in Fig. 5. UCS increases with an increase in the CP of soil. For a 2% cement content, the UCS of the soil was found to be 341.85 kPa at 7 days, 377.08 kPa at 14 days, and 444.24 kPa at 28 days. The curing period provides time to mobilize the cementitious behavior of cement. A larger curing period allows for more complete hydration, which improves the microstructure and higher strength. It shows that proper curing should be done to mobilize adequate hydration for soil mixed with cement.

1000

S+C 0% S+C 2 % at 7D S+C 4 % at 7D

500

STRESS (KPA)

0

0123456789101112

AXIAL STRAIN (%)

Fig. 3. Stress-strain behavior of soil mixed with different contents of cement

0 100 200 300 400 500

0 100 200 300 400 500 600 700

444.24

572.16

377.08

341.85

393.1

341.85

205.89

UCS (kPa)

UCS (kPa)

7

14

28

0

2

4

6

Curing Period (days )

Cement (%)

Fig. 4. Variation of the UCS with different cement content (CP=7 days)

Fig. 5. Variation of UCS with different CP (CC=2%)