The timeline for concrete dates all the way back to 12 million B.C. when limestone and oil shale first mixed together, a combustion that produced cement compounds. From then on, Egyptians and Romans used different elements to create cementitious materials and build imposing, iconic structures. Modern concrete differs from early concrete, but some of the same elements are present in both. Architectures have evolved, and so have the ways in which we utilize the materials to build them. In our blog, we’re going to take a step back and look at some early concrete structures and their compositions.
In 6500 B.C., Nabataea traders built the first concrete-like structures in regions of southern Syria and northern Jordan. They discovered hydraulic lime, which is cement that hardens underwater, and by 700 B.C., they built kilns to supply mortar to aid in the construction of underground cisterns and houses. They also used the same kilns that made pottery due to similar temperatures. The territory in which they lived allowed them to transform silica, which had groundwater seeping through, into a pozzolan material. Coupled with lime, they were able to produce cement for homes and floors.
The Great Pyramid of Giza is the oldest and largest of the three pyramids in the Giza Pyramid complex, built in 2580-2560 B.C. When one thinks of Egypt, the pyramids are the most iconic works of architecture that come to mind. Most people know that the pyramids were built from limestone, but gypsum and mortar were also involved. The Great Pyramid of Giza required about 500,000 tons of mortar. The cement binding was believed to be either silicon dioxide or a calcium and magnesium-rich silicate mineral, according to Professor Michel Barsoum from Drexel University. It is the oldest of the Seven Wonders of the Ancient World and has remained the most intact among the others.
One of the most famous ancient monuments is the Pantheon, built by the Romans. It is unknown as to who designed the monument, but it was completed around 126-128 A.D. during Emperor Hadrian’s reign. Because natural pozzolan had already been discovered, the Romans used it in addition to animal fat, milk, and blood. The Pantheon’s exterior foundation walls are made up of pozzolana cement – a mixture of lime, reactive volcanic sand, and water. The dome is supported by thick, concrete pillars created by parts of the exterior walls. Because of this, the Pantheon has remained intact all these millennia.
Looking back on these early concrete structures, we see the possibility that many of the materials used back then are still present in today’s construction work. The foundation is there, but we’ve incorporated different mixtures to ensure the structure stays intact and appealing for the modern period. That said, we can’t help but look in awe at the ancient monuments and wonder how the architects of that time accomplished such a historical feat.