Natural pozzolans for concrete

Mielenz, Richard C.; Greene, K.; Schieltz, N. C.

doi:10.2113/gsecongeo.46.3.311

Cited by 35 publications

(25 citation statements)

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“…The high silica content of the zeolites neutralizes excess lime produced by setting concrete, much like finely powdered pumice or fly ash. In the U.S., nearly $1 million was saved in 1912 during the construction of the 240-mile-long Los Angeles aqueduct by replacing Յ25% of the required portland cement with an inexpensive clinoptilolite-rich tuff mined near Tehachapi, CA (8,9). Lightweight Aggregate.…”

Section: Constructionmentioning

confidence: 99%

La roca magica: Uses of natural zeolites in agriculture and industry

Mumpton¹

1999

Proc. Natl. Acad. Sci. U.S.A.

716

425

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For nearly 200 years since their discovery in 1756, geologists considered the zeolite minerals to occur as fairly large crystals in the vugs and cavities of basalts and other traprock formations. Here, they were prized by mineral collectors, but their small abundance and polymineralic nature defied commercial exploitation. As the synthetic zeolite (molecular sieve) business began to take hold in the late 1950s, huge beds of zeolite-rich sediments, formed by the alteration of volcanic ash (glass) in lake and marine waters, were discovered in the western United States and elsewhere in the world. These beds were found to contain as much as 95% of a single zeolite; they were generally f lat-lying and easily mined by surface methods. The properties of these low-cost natural materials mimicked those of many of their synthetic counterparts, and considerable effort has made since that time to develop applications for them based on their unique adsorption, cation-exchange, dehydration-rehydration, and catalytic properties. Natural zeolites (i.e., those found in volcanogenic sedimentary rocks) have been and are being used as building stone, as lightweight aggregate and pozzolans in cements and concretes, as filler in paper, in the take-up of Cs and Sr from nuclear waste and fallout, as soil amendments in agronomy and horticulture, in the removal of ammonia from municipal, industrial, and agricultural waste and drinking waters, as energy exchangers in solar refrigerators, as dietary supplements in animal diets, as consumer deodorizers, in pet litters, in taking up ammonia from animal manures, and as ammonia filters in kidney-dialysis units. From their use in construction during Roman times, to their role as hydroponic (zeoponic) substrate for growing plants on space missions, to their recent success in the healing of cuts and wounds, natural zeolites are now considered to be full-f ledged mineral commodities, the use of which promise to expand even more in the future.The discovery of natural zeolites 40 years ago as large, widespread, mineable, near-monomineralic deposits in tuffaceous sedimentary rocks in the western United States and other countries opened another chapter in the book of useful industrial minerals whose exciting surface and structural properties have been exploited in industrial, agricultural, environmental, and biological technology. Like talc, diatomite, wollastonite, chrysotile, vermiculite, and bentonite, zeolite minerals possess attractive adsorption, cation-exchange, dehydration-rehydration, and catalysis properties, which contribute directly to their use in pozzolanic cement; as lightweight aggregates; in the drying of acid-gases; in the separation of oxygen from air; in the removal of NH 3 from drinking water and municipal wastewater; in the extraction of Cs and Sr from nuclear wastes and the mitigation of radioactive fallout; as dietary supplements to improve animal production; as soil amendments to improve cation-exchange capacities (CEC) and water sorption capacities; as soilless zeopon...

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Section: Constructionmentioning

confidence: 99%

La roca magica: Uses of natural zeolites in agriculture and industry

Mumpton¹

1999

Proc. Natl. Acad. Sci. U.S.A.

716

425

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“…As pozolanas são conhecidas por melhorar a trabalhabilidade (Mielenz, Greene, Schieltz, 1951;Mehta, 1987Mehta, , 2004, reduzir o calor de hidratação (Mielenz, Greene, Schieltz, 1951;Mehta, 1987;ACI 232, 1994), aumentar a resistência ao ataque de sulfatos e diminuir as expansões decorrentes das reações álcali-agregado (Mehta, 1987;ACI 232, 1994;Munhoz, 2007), e a durabilidade (Cook, 1986;Mehta, 1987;Mehta e Monteiro, 1994). No entanto, todas essas vantagens da mistura cimento portland-pozolana dependem de uma série de parâmetros, tais como, finura e forma das partículas, área superficial específica, relação água/cimento, composição, tipo e quantidade da pozolana, os quais influenciam na sua reatividade pozolânica (Mehta, 1987;ACI 232, 2000;Massazza, 2004).…”

Section: Pozolanas Naturaisunclassified

“…No entanto, todas essas vantagens da mistura cimento portland-pozolana dependem de uma série de parâmetros, tais como, finura e forma das partículas, área superficial específica, relação água/cimento, composição, tipo e quantidade da pozolana, os quais influenciam na sua reatividade pozolânica (Mehta, 1987;ACI 232, 2000;Massazza, 2004). Outros benefícios não menos importantes são aqueles relacionados com a redução dos custos de energia e da produção do cimento (Mielenz, Greene, Schieltz, 1951;Mehta, 1987;Yamamoto et al, 1997;Mehta, 2004;Isaia e Gastaldini, 2004;Hendriks et al, 2004); redução das emissões de CO 2 (Yamamoto et al, 1997;Penttala, 1997;Isaia e Gastaldini, 2004;Hendriks et al, 2004;WBCSD, 2002;MCT, 2010) e preservação de matérias primas e de fontes não renováveis de combustíveis, além de reciclar do meio ambiente, subprodutos de outros processos industriais (Yamamoto et al, 1997;Isaia e Gastaldini, 2004;Munhoz, 2007;WBCSD, 2009;MCT, 2010).…”

Section: Pozolanas Naturaisunclassified

“…Os teores de ál-calis de cada amostra são elevados e estão em torno de 7,5% do valor médio. A perda ao fogo pode ser considerada baixa, se comparada tanto com as tradicionais pozolanas de origem italiana (Massazza, 1993;Mehta, 1987), assim como com as norte-americanas (Faick, 1963;Mielenz, Greene, Schieltz, 1951).…”

Section: Os Trabalhos De Campo Identificaram Quatro Exposições De Vidunclassified

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Vidro vulcânico maciço: pozolana natural no oeste paulista

Montanheiro

Negri

Janasi

et al. 2011

Geol. USP, Sér. cient.

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“…Pumicite from the Ogallala formation near Ellis, Kan., which was tested for pozzolanic quality by the Bureau of Reclamation (Mielenz, Greene, and Schieltz, 1951), was found to reduce mortar expansion and increase mortar strength. The ash in the Wray area contains about 95 percent glass, which is slightly altered, and has an index of refraction of 1.497.…”

Section: Mineral Fillermentioning

confidence: 99%

General and engineering geology of the Wray area, Colorado and Nebraska

Hill¹,

Tompkin²

1953

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Natural pozzolans for concrete

Cited by 35 publications

References 0 publications

La roca magica: Uses of natural zeolites in agriculture and industry

La roca magica: Uses of natural zeolites in agriculture and industry

Vidro vulcânico maciço: pozolana natural no oeste paulista

General and engineering geology of the Wray area, Colorado and Nebraska

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