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From Coral to Roads: Formation of Limestone Deposits

Tuesday, February 26, 2019
Coral - Indiana, Illinois
Spent shell and coral fragments formed from marine organisms. In 20 million years, you could be driving on the limestone this will become on the roads in Aruba.

Limestone is a very common sedimentary rock, found around the world in various landscapes that once used to be the beds of small inland seas that contained salt water. It takes a lot of time, heat and pressure to materialize into the limestone that we are familiar with. Before limestone, and coral sand, can be used in road construction applications, it goes through several aggregate forming steps. This process spans tens of millions of years and produces the quality limestone that Shoreline delivers to asphalt plants, concrete plants and various paving job-sites throughout Northern Indiana and Southern Michigan.

Under water coral and reef beds. Birthplace of limestone aggregates.

Limestone contains over 50% calcium carbonate. There are two separate processes that take place which form coral. Before limestone can be spread as road base, it is spread across an ocean floor. Biochemical limestone starts as housing for sea creatures, marine organisms have the ability to process calcium carbonate from the sea water to from hard exoskeletal shells. Think of a scallop; you can eat them for dinner and drive on their shell sediment in roads. Chemical limestone is made by a process in which heat in the sea water helps to precipitate out calcium carbonate. It settles on already forming limestone and adds layers to its growth through a cementing process. The limestone strands that stretch from Northern Illinois into Southern Indiana were formed this way. Prior to the last ice age in which the entire Great Lakes region was frozen under ice, a salt water sea existed here.

The temperate bioclastic limestone that is found here was formed as marine organisms died and their exoskeletal remains fell to the sea floor. The soft parts decayed, leaving only the hard shells, which typically became broken down by current action and biological predators. Over long periods of time, the loose skeletal sediments are transformed into bioclastic limestone by the addition by the addition of a chemically precipitated carbonate cement between the shell fragments. In warm low-latitude waters of the tropics, this is called tropical bioclastic limestone. In cooler waters at mid and high latitudes, this is known as temperate bioclastic limestone.

Course limestone aggregate used on road shoulders in Aruba. It’s not well screened, as you can see the Close up of street side. Course aggregates including limestone and limestone sand. Not very well screened, but economical for road shoulder material to compliment asphalt.

Shoreline is a sand and gravel supplier that only delivers quality products.   Whether you are completing a large or small project, Shoreline will bring you quality products at a great price.   For highway projects, we offer state approved aggregates and rip rap.   If you need to build a golf course or keep it maintained, Shoreline has the products you needs. We are the sand and gravel supplier you need to help with your next project. Contact Shoreline today to learn more about our services and to order material.