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.
Concrete is a hardened material that forms when a mixture of cement, sand, crushed stone and water is poured into moulds or formwork and allowed to cure or harden. Cement is made by strongly heating a mixture of limestone, silica and clay in a kiln until small pea-sized lumps called âclinkerâ form.This is then ground to a powder, the key ingredients of which are dicalcium silicate, tricalcium silicate, tricalcium aluminate and calcium oxide.Kiln reactions include:ement is made by strongly heating a mixture of limestone, silica and clay in a kiln until small pea-sized lumps called âclinkerâ form. This is then ground to a powder, the key ingredients of which are dicalcium silicate, tricalcium silicate, tricalcium aluminate and calcium oxide. Kiln reactions include: