Effect of Mixing Time and Two-Stage Mixing Approach on the Fresh and Hardened Properties of Concrete
DOI:
https://doi.org/10.65568/gujes.2026.020206Keywords:
Concrete, Mixing time, Two-Stage Mixing Approach, Compressive strength, Workability, DensityAbstract
Concrete mixing is one of the key stages that directly affects the homogeneity of concrete constituents and, consequently, its fresh and hardened properties. The choice of mixing time and mixing method plays an important role in determining workability, compressive strength, and the overall quality of concrete. This study investigates the effect of mixing time and the Two-Stage Mixing Approach (TSMA) on selected fresh and hardened concrete properties. An experimental program was conducted using five concrete mixes made with the same materials and sources. Four mixes were prepared using conventional mixing times of 3, 6, 9, and 12 minutes, while one mix was prepared using TSMA. A total of 30 concrete cubes (150 × 150 × 150 mm) were cast, with six cubes for each mix; three specimens were tested at 7 days and the other three at 28 days. The study included slump, density, and compressive strength tests, in addition to laboratory testing of the constituent materials according to the relevant standards. The results showed a gradual reduction in slump and compressive strength with increasing mixing time in the conventional mixes. The 28-day compressive strength decreased from 41.70 MPa for the reference mix to 37.04 MPa when the mixing time increased to 12 minutes. The TSMA mix exhibited the highest workability, with a slump of 18 cm, but it showed lower compressive strength than the conventional mixes of similar proportions. Overall, the findings indicate that increasing mixing time beyond a certain limit may adversely affect some concrete properties, and improved workability does not necessarily lead to higher compressive strength.
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