Ancient geopolymers in South-American Monuments, Part IV(*): use of natural andesite volcanic sand (not crushed).

Journal on Geopolymer Science Applied to Archaeology
2020, Vol. 1, p. 36-43


By Prof. Joseph Davidovits, Geopolymer Institute (France).
Frédéric Davidovits, Ph. D., Geopolymer Institute (France).


The studies carried out in 2017-2018 on the monumental stones constituting the Pumapunku site in Bolivia (South America) provided evidence that the stones are ancient artificial geopolymers (Parts I to III). To make geopolymer andesite stone, around AD 600 to AD 700, the builders could have transported an andesite stony material having the consistence of sand from the Cerro Khapia volcano site, and added an organo-mineral geopolymer binder manufactured with local biomass ingredients. They did not use the many quadrangular volcanic blocks, the famous “piedras cansadas”, the tired stones, which are still lying on both sides of the lake Titicaca. The present paper describes how the builders of Pumapunku / Tiwanaku exploited a natural volcanic andesite sand from the volcano Cerro Khapia, transported and stored it at the shore village of Iwawe, Stratum (V) in the excavation by Isbell & Burkholder, (2002). For the making of their andesite geopolymer monuments, they did not need to crush andesite rock. This andesite sand is similar to one of the pozzolana sands found in the best ancient Roman mortars and coined in Latin “carbunculus”, 2000 years ago.

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