The asteroid belt is nothing but tourist traps, and the rest stops really thin out after Saturn. Some of you will want to consider flying. Luckily, at a Boeing 777's maximum velocity of 590 miles per hour, the trip to Pluto will take only about 680 years.
Yet structures like the Pantheon and the Colosseum have survived for centuries, often with little to no maintenance. Geologists, archaeologists and engineers are studying the properties of ancient Roman concrete to solve the mystery of its longevity. âRoman concrete is . . . considerably weaker than modern concretes. Itâs approximately ten times weaker,â says Renato Perucchio, a mechanical engineer at the University of Rochester in New York.
In contrast to modern concrete structures, the concrete used in Roman buildings was usually covered with brick or stone. Concrete is a composite material composed of coarse aggregate bonded together with a fluid cement that hardens over time. Most concretes used are lime-based concretes such as Portland cement concrete or concretes made with other hydraulic cements, such as ciment fondu.