Pozzolan
**History of Pozzolan**
– Mixtures of calcined lime and active aluminosilicate materials were used in Ancient world architecture.
– Ancient Greeks used volcanic materials dating back to 500-400 BC.
– Romans widely adopted volcanic pumices and tuffs for construction.
– Knowledge about pozzolans was lost with the decline of the Roman empire.
– Pozzolans became common additions to Portland cement concrete mixtures in the 20th century.
**Types of Pozzolanic Materials**
– Pozzolans vary in origin, composition, and properties.
– Natural and artificial pozzolans with pozzolanic activity are used in cement.
– Common pozzolans include fly ash, silica fume, metakaolin, and rice husk ash.
– Natural pozzolans are abundant in locations like Italy, Germany, Greece, and China.
– Exploration of alternatives to established pozzolanic by-products is ongoing due to limited supply.
**Benefits and Use of Pozzolan**
– Economic gain, environmental cost reduction, and increased durability are benefits of pozzolan use.
– Blending pozzolans with Portland cement can reduce pollution without compromising strength.
– Pozzolans contribute to higher compressive strength, better performance, and greater durability.
– Pozzolanic reaction in blended cements refines pore structure and reduces permeability.
– Pozzolan-blended cements offer increased chemical resistance and improved durability.
**Related Concepts**
– Alkali-aggregate reaction (AAR) and alkali-silica reaction (ASR) are chemical reactions damaging concrete.
– Caesarea Maritima is an ancient Levantine city and depopulated village.
**References**
– Mehta, P.K. (1987). Natural pozzolans: Supplementary cementing materials in concrete.
– Snellings, R.; Mertens G.; Elsen J. (2012). Supplementary cementitious materials.
– Spence, R.J.S.; Cook, D.J. (1983). Building Materials in Developing Countries.
– Idorn, M.G. (1997). Concrete Progress from the Antiquity to the Third Millennium.
– Schneider, M.; Romer M.; Tschudin M.; Bolio C. (2011). Sustainable cement production – present and future.
– Additional citations related to pozzolans and concrete materials.https://en.wikipedia.org/wiki/Pozzolan