Final answer:
Limestones, rich in calcium carbonate, are used as a supplementary cementitious material in concrete, contributing to its strength and durability as well as environmental benefits by reducing CO2 emissions during cement production.
Step-by-step explanation:
Limestones are utilized in construction material as a supplementary cementitious material due to their high content of calcium carbonate (CaCO3). When processed as quicklime or slaked lime, limestones contribute to the binder properties of mortar and concrete. The Romans enhanced this by using volcanic sand called pozzolana, which reacted with lime to form a mortar with superior strength and durability, even setting underwater. In modern times, limestones can be used in various forms, such as ground limestone filler, to modify the properties of concrete, making it a versatile and valuable component in the mixture.
Importantly, limestone as a material in concrete provides environmental benefits. Notably, certain types of cement can incorporate limestone as a supplementary cementitious material to reduce the amount of clinker required in cement production, which can significantly diminish CO2 emissions associated with the manufacturing process.