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A reduction of 40 percent of Portland cement in the concrete mix is usually feasible when replaced with a combination of pozzolanic materials. Pozzolans can be used to control setting, increase durability, reduce cost and reduce pollution without significantly reducing the final compressive strength or other performance characteristics.
Pozzolana from Mount Vesuvius volcano, Italy. Pozzolana or pozzuolana (/ ˌ p ɒ t s (w) ə ˈ l ɑː n ə / POT-s(w)ə-LAH-nə, Italian: [potts(w)oˈlaːna]), also known as pozzolanic ash (Latin: pulvis puteolanus), is a natural siliceous or siliceous-aluminous material which reacts with calcium hydroxide in the presence of water at room temperature (cf. pozzolanic reaction).
However, adding high-reactivity pozzolans into the concrete mix prevents such a conversion reaction. [66] In sum, whereas pozzolans provide a number of chemical pathways to form hardened materials, "high-reactivity" pozzolans such as blast furnace slag (GGBFS) can also stabilise certain pathways. In this context, EMCs made from fly ash have ...
Portland pozzolan cement includes fly ash cement, since fly ash is a pozzolan, but also includes cements made from other natural or artificial pozzolans. In countries where volcanic ashes are available (e.g., Italy, Chile, Mexico, the Philippines), these cements are often the most common form in use.
The pozzolanic activity is a measure for the degree of reaction over time or the reaction rate between a pozzolan and Ca 2+ or calcium hydroxide (Ca(OH) 2) in the presence of water. The rate of the pozzolanic reaction is dependent on the intrinsic characteristics of the pozzolan such as the specific surface area , the chemical composition and ...
Cement: cement, chemically speaking, is a product that includes lime as the primary binding ingredient. Lime (calcium oxide) was used on Crete and by the ancient Greeks. There is evidence that the Minoans of Crete used crushed potsherds as an artificial pozzolan for hydraulic cement.
The filler effect is immediate, while the effect of pozzolanic reaction occurs between 3 and 14 days. [10] In the mid-2010s, Limestone Calcined Clay Cement mixture incorporating even more than 20% metakaolin was developed as a lower-carbon cement substitute. The technology is on the commercialization stage in the 2020s.
Trass is the local name of a volcanic tuff occurring in the Eifel, where it is worked for hydraulic mortar.It is a grey or cream-coloured fragmental rock, largely composed of pumiceous dust, and may be regarded as a trachytic tuff.