PSI - Issue 70

Surya Mouli R. et al. / Procedia Structural Integrity 70 (2025) 239–246

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used standard 150 mm cubes and followed IS 516:2018 at curing periods of 7, 14 and 28 days. The laboratory tested flexural strength on 100 × 100 × 500 mm prisms in accordance with IS 516:2018. Concrete drying shrinkage was evaluated using prism specimens of 75 mm x 75 mm × 285 mm. After 24 hours of casting, the specimens were demoulded and cured in water for 7 days. The samples were dried further in a hot air oven set to 50 ± 2°C. To calculate drying shrinkage, the change in length was measured at regular intervals with a length comparator and the final drying shrinkage value was determined after 28 days of drying in a hot air oven, in accordance with IS 1199:1959. Water absorption tests were also done in accordance with ASTM C642 – 13. Three identical test specimens were utilized to achieve results that reflected accuracy and repeatability. The test set up for few tests are depicted in Fig.2.

(c)

(a)

( b)

Fig.2(a). Slump test; Fig.2(b). Testing of cube; Fig.2(c). Water absorption test

4. Discussion of Experimental Findings The study examined different concentrations from 0% to 2% (by weight of cement) to assess their impact on concrete properties during fresh and hardened states. The analysis of workability (slump) and compressive strength and shrinkage parameters evaluated bio-based starch gel performance against the control mix. The findings have been assessed to determine the optimal dose levels and relative effectiveness of corn and tapioca starch for enhancing internal curing. Table 3 shows the summary of test outcomes of CM and starch gel added mix.

Table.3. Summary of test outcomes Mix ID Slump (mm)

Compressive strength (MPa)

Split tensile strength (MPa)

Modulus of rupture (MPa)

Drying Shrinkage (mm)

28 th day

7 th day

28 th day

7 th day

28 th day

7 th day

3.72 3.84 3.94 4.11 4.00 3.86 3.69 3.58 3.90 4.05 4.18 4.30 4.10 3.92 3.75

3.50 3.65 3.78 3.90 3.80 3.60 3.40 3.25 3.70 3.85 4.00 3.88 3.75 3.59 3.45

5.28 5.43 5.60 5.85 5.71 5.42 5.11 4.90 5.50 5.76 5.94 5.90 5.68 5.41 5.22

0.081 0.072 0.066 0.060 0.063 0.068 0.072 0.076 0.074 0.067 0.064 0.058 0.062 0.066 0.070

CM 87

29.25 30.10 31.30 33.50 32.00 31.00 29.50 28.20 30.50 31.80 34.00 35.50 31.60 30.20 29.00

45.63 46.20 47.50 48.80 47.00 46.00 44.50 43.30 46.30 47.80 49.20 51.00 47.70 46.10 44.90

2.45 2.58 2.69 2.83 2.76 2.63 2.51 2.40 2.60 2.75 2.88 3.00 2.85 2.70 2.55

CS-0.5

83

CS-0.75 80

77

CS-1.0

CS-1.25 72

CS-1.5

70

CS-1.75 65

60 84

CS-2.0 TS-0.5

TS-0.75 82

TS-1.0

79

TS-1.25 76

TS-1.5

74

TS-1.75 70

TS-2.0

66