I had a customer one time ask the question if there is really gravel inside of concrete. The answer is yes. Gravel is one of the four primary ingredients in concrete.
If you were to go to the hardware store and buy a bag of regular ugly parking lot gravel, buy a bag of regular sand, buy a bag of Portland cement, and mix those three together with some water you will have concrete.
So why is there gravel in concrete? Basically to make it stronger. Without the gravel, concrete would be more brittle and would not be as resilient as it is with gravel. There are various concrete mixes, aka, recipes where different variations of gravel are used, bigger sizes, smaller sizes, mixtures of sizes for various uses of concrete. Engineers spend lots of time determining load calculations for the best gravel for particular situations.
Good news and more good news. Gravel is relatively inexpensive and when put into concrete as one of the primary ingredients makes concrete super strong and has wide variety of uses. More good news is that when the concrete is finished the workers smooth out, or float the concrete which will essentially push the gravel down inside so you don't see it.
Hope this helps to clear up some mysteries about what is inside of concrete. Feel free to call or email us anytime.
Salzano Custom Concrete