We've speculated many times about how the ancient Egyptians may have been able to hoist so many large heavy stones into place. A new theory says that some of the giant building blocks in the pyramids may actually be made of concrete, which is much lighter in weight than limestone.
Most Egyptologists think the pyramids were built out of limestone blocks from nearby quarries, despite the fact that the metals available to the ancient Egyptians would have made this quarrying process extremely difficult. Nevertheless, the quarries exist, so it must have been done. However, how the blocks were then moved and laid, is an even bigger question, and if they were first ground into powder, then made into concrete, it would have been a much easier process. One of the ingredients in cement is powdered limestone, which is heated after being mixed with other ingredients, such as clay, sand and iron ore.
The ancient Romans built extensively with cement, but this was 2,500 years after the pyramids were built. Engineer Michel w. Barsoum, who is an Egyptian native, thinks that the concrete blocks may have been used in the inner and upper layers, while limestone was used for the rest, which is what would have caused the confusion. Barsoum argues that although indeed the majority of the stones were carved and hoisted into place, crucial parts were not. The ancient builders cast the blocks of the outer and inner casings and, most likely, the upper parts of the pyramids using a limestone concrete.
In the November 30th issue of the New York Times, John Noble Wilford quotes geologist David Walker as saying that a microscopic examination of the blocks "certainly revealed things you wouldn't expect to find in normal limestone."The type of concrete pyramid builders used could reduce pollution and outlast Portland cement, the most common type of modern cement. Portland cement injects a large amount of the world's carbon dioxide into the atmosphere and has a life span of about 150 years. If widely used, a geopolymer such as the one used in the construction of the pyramids can reduce that amount of pollution by 90% and last much longer. The raw materials used to produce the concrete used in the pyramids--lime, limestone and diatomaceous earth--can be found worldwide and it is affordable enough to be an important construction material for developing countries.
The longstanding belief has been that the pyramids were constructed with limestone blocks that were cut to shape in nearby quarries using copper tools, transported to the pyramid sites, hauled up ramps and hoisted in place with the help of wedges and levers. Barsoum's findings provide long-sought answers to some of the questions about how the pyramids were constructed and with such precision. It puts to rest the question of how steep ramps could have extended to the summit of the pyramids; builders could cast blocks on site, without having to transport stones great distances. By using cast blocks, builders were able to level the pyramids' bases to within an inch. Finally, builders were able to maintain precisely the angles of the pyramids so that the four planes of each arrived at a peak.
Although these findings answer some of the questions about the pyramids, Barsoum says the mystery of how they were built is far from solved. For example, he has been unable to determine how granite beams--spanning kings' chambers and weighing as much as 70 tons each--were cut with nothing harder than copper and hauled in place.
Zahi Hawass, who is in charge of Giza Pyramid research, vehemently denies that concrete was used, although he does admit that it has been used to repair the pyramids many times over the centuries.
If you're fascinated by ancient Egypt, you should know that Dreamland co-host William Henry leads a tour there every year, and he plans a new one in 2007 with John Anthony West, who was recently interviewed by William on Dreamland. Subscribers can still listen to this fascinating interview, as well as to his special subscriber interview with Whitley, in which they both discuss their experiences in the Gurdjieff work.
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