Which of the following factors would likely increase the specific gravity of coarse aggregate?

• A. Increased porosity
• B. Higher mineral density
• C. Aging of the material
• D. Surface moisture

Answer: (B)

Higher mineral density directly contributes to an increase in the specific gravity of coarse aggregate. Specific gravity is a measure of the density of a material compared to the density of water. When the mineral density of aggregate increases, it means that there is more mass per unit volume of that aggregate. Specifically, aggregates with denser minerals, such as granite or basalt, will have a higher specific gravity compared to aggregates made up of lighter minerals, such as sandstone. Thus, if the mineral density of the coarse aggregate is increased, the specific gravity will rise accordingly, indicating that the material is heavier relative to the same volume of water.

This understanding underscores the importance of mineral composition in the performance and selection of aggregates for construction purposes, where specific gravity plays a significant role in determining the suitability and strength of the material in concrete or other applications.