<![CDATA[Presently, the construction project is encountering numerous issues, including the concrete quality deviating from specifications due to the extended distance from the Batching Plant to the project site, as well as an excessive use of admixtures intended to prevent the concrete from freezing initially. This study aims to optimize the dose of type D admixture, namely Plastiment 83 AM, in increasing the compressive strength and normal concrete microstructure. Concrete was tested with variations in admixture dosage (0%, 0.15%, 0.25%, 0.35%, and 0.40%) as well as mixing time (15 minutes, 2 hours, 4 hours, 6 hours, and more than 6 hours). The tests included compressive strength analysis at 7, 14, 28, and 56 days of age, as well as microstructure analysis using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The results showed that the optimal admixture dose of 0.15% in the first 2 hours and 0.10% in the next 2 hours produced the highest compressive strength of 19.84 MPa at 56 days of age, an increase of 17% compared to control concrete without admixtures which only reached 16.96 MPa. This value also exceeded the target value of 18.68 MPa. SEM analysis showed that the optimum dose caused a denser concrete microstructure with evenly distributed pores, and FTIR showed an increase in the intensity of Si-O peak, signifying better Calcium Silicate Hydrate (C-S-H) gel formation. On the other hand, overdose of admixture (0.40%) and more than 6 hours of mixing time resulted in segregation of the material, high porosity, and decrease in compressive strength by as much as 12.99 MPa (decrease by 23% compared to control concrete). A dosage of 0.15% of Plastiment 83 AM during the first 2 hours and 0.10% during the next 2 hours is recommended in this study to achieve optimum concrete performance.]]>
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