The construction of the Great Pyramid at Giza is usually associated with enormous stone blocks, quarries, ramps and a complex system for moving them. According to a controversial theory, however, some of the blocks were not transported as finished pieces but were made on site by pouring a concrete-like mixture.
The Great Pyramid was built as the tomb of Pharaoh Khufu, also known as Cheops, in the 27th century BC. It is precisely the scale of the construction that continues to fuel interest in how the ancient Egyptians managed to quarry, transport and place such a huge number of stone blocks.
The Limestone “Concrete” Theory
The first detailed version of this hypothesis was proposed in the 1970s by French chemist Joseph Davidovits. According to him, the ancient builders used a mixture of powdered limestone, diatomite, clay, sodium carbonate and lime. The material was placed in wooden molds positioned at the required height, where it hardened.
The idea is based on analyses of samples from the pyramid. In subsequent studies, other scientists did not find sufficiently convincing evidence that they were remnants of an artificially prepared mixture. In their view, the fragments could be pieces of natural stone or construction mortar.
“Most researchers still believe that Davidovits’s concept has little to do with reality,” writes Szymon Zdzieblowski in his book about the Great Pyramid.
Why the Theory Is Attracting Attention Again
At the beginning of the 21st century, Belgian physicist Guy Demortier revived the discussion. According to him, the traditional explanation raises a serious question about the pace of construction. If the pyramid was completed in no more than 30 years, approximately one block measuring around one cubic meter would have had to be placed on the construction site every minute.
Demortier examined samples using X-ray methods and magnetic spectroscopy. He recorded a limestone content of between 85 and 92 percent, but also pointed to characteristics that, in his view, distinguish the material from the natural limestone in the known quarries near Giza. His conclusion is that some of the blocks may have been made on site in wooden molds.
A similar position is defended by materials scientist Michel Barsoum of Drexel University. He allows that although most of the stones were quarried and moved, certain sections of the pyramids may have been built from limestone concrete.
What Remains Unproven
The theory has not gained broad acceptance among Egyptologists and archaeologists. One of the main problems is the small number of samples and their uncertain origin. It is not always known which part of the pyramid they were taken from, nor under what conditions they were collected.
Zdzieblowski places precisely this question at the center of his criticism: “In practice, we have no idea where the samples that are supposed to support the concrete theory came from. Are they certainly from the Great Pyramid? And even if they are, from which part of it?”
According to him, the fragments studied may have been remnants of the mortar that binds the stone blocks together. Thus, the laboratory results could be genuine but misinterpreted because of the uncertain origin of the material.
Therefore, the dispute remains open only regarding the limited use of artificial stone, not a complete reassessment of the construction of the Egyptian pyramids. Some studies find grounds for a limestone mixture in individual elements, while others identify the blocks as natural limestone with traceable geological characteristics.
Sources: wielkahistoria.pl