Title: Reproduction of Ancient Cementitious Material Used in China 5000 Years Ago
Author(s): K. Asaga, M. Daimon, Z. X. Li, and K. Yokozeki
Publication: Symposium Paper
Appears on pages(s): 123-138
Keywords: cementitious; concrete; hydraulic cement; materials
In China, ancient concrete was excavated in which a hydraulic type of cement resembling modern cement was supposed to have been used. This paper gives first, detailed characterization on the raw stone of this ancient cement both from chemical and mineralogical point of view. Also, an attempt has been made to reproduce the ancient cementitious material by burning the raw stone. The change in the hydration products and mechanical properties of hardened specimen were pursued during a hydration test, and the results can be summarized as follows. l The raw stone bears a striking resemblance in chemical composition to the modern ordinary Portland cement (as recalculated in the de-carbonated form). l Small crystal size silicious species such as quartz, clay, mica and feldspar were well dispersed in the texture of the raw stone. l B -Ca,SiO, was observed in the burned stone at 1000°C. l An increase in hydration products( CSH and Ca(OH) 2 ) were observed with progress of hydration. l The hydrated paste specimen showed a compressive strength of 10 MPa at 28 days with a w/c of 0.60.