Concrete is a mixture of cement, water, sand, gravel, crushed rock, or other aggregates. Sometimes, one or more admixtures are added to change certain characteristics of the concrete, such as workability, durability, and time of hardening.
Top 100 Colleges by Highest Tuition. Here are the top 100 most expensive colleges by tuition for the 2008-2009 school year. The latest numbers can be found in our most expensive colleges ranking. Notes: Some colleges like Bates College, Colby College, Middlebury College, and Union College have a comprehensive fee (tuition + room/board).
This year 's list of the best universities in the world features 147 of the top universities in the US â with 63 American universities making the top 200 of the list , including the California Institute of Technology ( Caltech ) as the world âs number one university , followed by Stanford University in third place , the Massachusetts Institute of ...