It's common knowledge that concrete begins with water and a dry cement substance that are mixed together, poured into a mold that then becomes very hard. But that is probably the end of most people's knowledge on the subject.
But there is also aggregate and other chemicals that are put into it. Cement has a lot of weight. Think of a square yard. That square yard of concrete weighs 3,700 pounds coming down the chute of the cement truck. If that yard is poured and then dried, it then weighs 3,500 pounds. And that's just for a yard. Think of how many yards a basement floor and walls has. Now the difference in one yard of wet and then dried concrete is 200lbs. The concrete is missing 200lbs which equals about 38 gallons of water. They are supposed to vibrate the concrete in most cases to get the air pockets out, but you are always going to have some minor air pockets. When the water evaporates, you'll have air pockets.
You need to know what you are doing with the concrete or you will get yourself in trouble. You need to choose a contractor that is aware of the nuances of concrete if it dries too quickly or in the cold you'll have foundation problems.
For more information, contact A1 Foundation Crack Repair.