What's the difference between cement and concrete?

Cement is an ingredient in concrete. Cement is manufactured through a process where numerous products are ground, mixed and then heated to a very high temperatures to create the finished product. Concrete utilizes cement as a glue to hold together a mixture of stone, sand, water and cement.

Is it a good idea to put a sealer on new concrete surfaces?

Yes. Sealers, applied correctly, help concrete reach its maximum strength and become more durable. 

Why does concrete crack?

Concrete has the same characteristics of a sponge. Concrete is just like the sponge that you leave on the edge of the sink after you washed the dishes. When the water leaves the sponge, the corners curl towards each other. Concrete goes through the same process as the sponge, but the sponge does not have the weight the concrete does. The concrete dries and gravity takes over. The concrete cracks where it needs relief from the stresses of drying. To alleviate this problem, it is important to have proper cutting during finishing and to have your saw joints cut at the proper depth and width.