Why is it important to eliminate organic impurities from aggregate materials?

Eliminating organic impurities from aggregate materials is crucial primarily because they can weaken the bond between the aggregates and the cement or asphalt. Organic materials, such as vegetation, decomposed plant matter, and other organic contaminants, may interfere with the chemical processes that occur during the curing of concrete or when asphalt is applied. This interference can lead to a weaker overall structure, reduced durability, and compromised load-bearing capacity of the finished product. In contrast, the presence of such impurities does not enhance color, increase weight, or improve water retention, which would not contribute positively to the performance of aggregate materials in construction applications. Thus, ensuring that aggregates are free of organic impurities serves to maintain the integrity and durability of construction projects.