#160;Photo: Bruno Girin/Flickr.comEverybody knows the Egyptians used huge stone blocks to build their pyramids. Some engineers arenrsquo;t so sure. Wersquo;ll listen to the argument. Today, on Engineering Works!Everybody learned in school that ancient Egyptian engineers used thousands of huge limestone blocks to build the pyramids. What we didnrsquo;t learn was how the Egyptians got those blocks from the ground to the top of those pyramids.Archaeologists and engineers have speculated for decades about how they did it. Sloping ramps. Rollers. Gangs of sweating slaves. Yoursquo;ve seen the movies. But nobody knows for sure.Now, materials engineers have come up with a new explanation that has the archaeologists in an uproar. Maybe some of those huge limestone blocks werenrsquo;t really limestone. And maybe those gangs of slaves didnrsquo;t push them up the ramps after all.The engineers think just maybe the Egyptians invented an early kind of concrete from crushed limestone and binders that work just like the Portland cement in modern concrete. Since the powdered limestone would be just like the limestone in limestone blocks, it would be really hard to tell the difference.So maybe instead of thousands of slaves pushing huge blocks of stone around, they were carrying bags of wet concrete and pouring it into forms on top of the half-built pyramids. Not as mysterious and romantic as big blocks of stone, but it could have worked.We havenrsquo;t been pushing stone or carrying concrete, but wersquo;re still done. See you next time.EngineeringWorks! is made possible by Texas AM Engineering and produced by KAMU-FM in College Station. Learn more about engineering. Visit us on the World Wide Web. Engineeringworks.tamu.edu.