PSI - Issue 70

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

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4.1 Slump Test The workability of corn starch (CS) and tapioca starch (TS) mixtures decreased while the starch gel dosage amounts increased. Workability measurements from control mix (CM) reached the highest value of 87 mm as its slump exceeded all other mixes. When adding starch in CS and TS mixes the workability decreased through rising starch gel dosages. The slump measurement of CS-0.5 started at 83 mm but reached 60 mm when the dosage reached CS-2.0. The TS-0.5 mix started with a slump value of 84 mm which dropped to 66 mm when reaching TS-2.0. The increased water retention ability of starch gel effectively removed available free water from the concrete mixture thus lowering the slump (Dang et al.,2017). The concrete lost its workability because of these changes. The TS mixing condition resulted in slightly higher slump measurements than CS mixes because tapioca starch retained its workability qualities better after the slump measurement threshold than corn starch. 4.2 Compressive Strength The compressive strength of the concrete mixtures was noted to enhance with the incorporation of starch gel up to a specific dose, as illustrated in Fig.3. The strength values for maize starch (CS) and tapioca starch (TS) were maximized at dosages of 1.0% and 1.25%, respectively. At these dosages, the compressive strength at 28 days peaked, with CS-1.0 exhibiting a value of 48.80 MPa and TS-1.25 attaining 51.00 MPa. This signified that these dosages were excellent for augmenting the concrete's strength. Exceeding these dosages resulted in a decline in strength, likely due to an superfluity of starch gel, which increased the water content in the mixture and diminished overall strength growth (Woyciechowski, et al.,2018; The control mix (CM) exhibited a compressive strength of 45.63 MPa at 28 days, which was inferior to the optimal mixes with starch gel.

Fig.3 Compressive strength results

Fig.4 Split tensile strength results

4.3 Split Tensile Strength Fig.4 depicts the test findings on tensile strength. The concrete mixtures obtained their highest split tensile strength outcomes when both corn starch (CS) and tapioca starch (TS) gels were added up to their optimal dosage rates. The CS mixes achieved their maximum tensile strength values of 2.83 MPa at seven days and 4.12 MPa at twenty-eight days when incorporating 1.0% gel content. The strength measurement displayed a minor reduction after the point of maximum gain. The TS concrete mixes achieved their peak tensile strength of 3.00 MPa and 4.30 MPa at a gel dosage of 1.25%. After reaching the optical gel concentration the strength values began to decline gradually. The tensile strength improvement resulted from improved hydration and microstructure together with better internal curing