Old types of concrete were invented centuries ago. If interested you can read the history of concrete. For us the only type we care about is the modern Portland cement which is used to make concrete. It is a great building material able to stand thousands of pounds of compression. Its durability makes it the natural choice for foundation, basement floors and garage floors.
When concrete is poured into place and given time to dry it will naturally shrink a little and crack. Minor cracks are normal and to be expected. Basically all concrete cracks. When floors are poured often lines are drawn into the non hardened concrete with a tool called a groover. The purpose of the groover is to control the location of the cracks that will develop. During inspections we often come across cracks in the concrete floors and foundations. Often this is an area of concern for home buyers. Home buyers do not need to be overly concerned. It is a good idea to keep an eye on any cracks, however it normal for the cracks to be there. Typically any crack on a foundation wall 1/8″ or less is considered small and normal. This goes for floor cracks as well. Floor cracks even if larger are not a structural concern and can be patched to improve the looks of the floor.
In the image you can see the cracks that formed where the groover was used. This is normal and occurred as the concrete company had planned. Nothing to worry about here.
Comment regarding radon: Cracks in the floor can be an easier way for soil gas and therefore radon to enter into a home. If we did radon testing and the tests were higher than recommended then you should contact a radon mitigation company., If you were to have a radon mitigation company mitigate radon in your home they should seal the cracks as part of their mitigation.
Jim Troth is a Manager of a multi inspector company, Habitation Investigation, in Ohio and the former Education Coordinator for InterNachi Ohio. He attributes the growth to excellent customer service and referrals from satisfied clients. The company provides home inspections in the Central Ohio Columbus and home inspections in the Dayton Ohio area, Hilliard, Powell, Pickerington, Pataskala, New Albany, Delaware, Gahanna, Westerville, Galloway, Grove City, Worthington, Dublin, Marysville, London, West Jefferson, Mechanicsburg and other cities surrounding Columbus, Ohio. His home inspection company is Habitation Investigation LLC. The website is: http://www.homeinspectionsinohio.com