A Nashville geotechnical engineering company is testing the concrete being used to build the city's Music City Center. Under a $1.5 million contract, the company is testing how foot-long cylinders of solid concrete being used in the center crumble under pressure. "Everyone thinks concrete is just a regular commodity," said concrete expert Rich Mote. "It's not. It's a chemical, and there's lots of chemistry involved. We make sure it's the right thickness, the right density."