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 500400 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 byproducts 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. Pozzolanblended cements offer increased chemical resistance and improved durability. Related Concepts Alkaliaggregate reaction (AAR) and alkalisilica 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.