Enhancing mechanical properties of roller-compacted concrete using different natural liquid admixtures

Roller-compacted concrete (RCC) is valued for its strength and cost efficiency in infrastructure applications, yet the use of conventional chemical admixtures raises environmental and health concerns. This study investigates natural liquid admixtures pomegranate (P), mulberry (M), grape (G), and date (D) extracts as sustainable alternatives to improve the physical, mechanical, and microstructural properties of RCC. Laboratory testing included water absorption, compressive strength, flexural strength, and splitting tensile strength at various curing ages. All mixes incorporating natural extracts performed better than the control. Pomegranate extract achieved the lowest water absorption (3.40%) and the highest flexural and tensile strengths, reflecting enhanced density and durability. Date extract produced the highest compressive strength (36.25 MPa at 90 days), exceeding the control by 17.5%. Microstructural analysis further confirmed that the extracts increased C–S–H formation and reduced porosity and microcracking. Overall, the findings show that fruit-based natural admixtures can significantly enhance RCC performance while reducing reliance on synthetic additives.