Results 171 to 180 of about 1,825 (209)

Natural pozzolans for concrete

Economic Geology, 1951
Many geologic formations in the United States yield pozzolans or materials which can be converted into pozzolans by grinding and calcination. When properly selected, processed, and used, pozzolans will reduce costs, improve quality of concrete, protect concrete against effects of reaction between aggregate and cement alkalies, and inhibit attack by ...
Richard Childs Mielenz, Kenneth Titsworth Greene, Nicholas Cyril Schieltz   +2 more
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Evaluation of pozzolanic activity of natural and artificial pozzolans by thermal analysis

Thermochimica Acta, 2004
Abstract In this research, the pozzolanic activity of natural and artificial pozzolan used for preparation of restoration mortars was evaluated. For this purpose, several pastes were prepared, by mixing two artificial pozzolans and a natural one with commercial hydrated lime, in different ratios. The pastes were cured in standard conditions (RH = 98%,
Antonia Moropoulou, Asterios Bakolas, Eleni Aggelakopoulou   +2 more
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The long-term durability performance of gypsum–Portland cement–natural pozzolan blends

Cement and Concrete Research, 2002
The density, workability, porosity, strength development, and durability of gypsum-Portland cement-natural pozzolan blends are discussed in this paper. The results indicate that the variation in proportions of the mix constituents causes changes in the ...
Colak, Adnan
exaly   +2 more sources

Pozzolanic activity of natural pozzolan–lime pastes and physicomechanical characteristics

Journal of Thermal Analysis and Calorimetry, 2018
In order to evaluate the pozzolanic activity of a natural pozzolan (NP) of rhyolitic composition, several pastes were prepared by mixing the pozzolan with hydrated lime, in different ratios. The pastes were stored in standard conditions (RH = 99 ± 1%, T = 25 ± 1 °C) and evaluated using thermal analysis (TG-DTA), X-ray diffraction, compressive strength ...
Asterios Bakolas, Eleni Aggelakopoulou
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Influence of the fineness of pozzolan on the strength of lime natural-pozzolan cement pastes

Cement and Concrete Research, 1994
Abstract The fineness of a cement is an important factor affecting the rate of strength development. This paper examines the importance of the fineness of natural pozzolans to the strength development of lime-pozzolan cements (LPCs). A natural pozzolan from Bolivia, which is typical of natural pozzolans found in South and Central America, was ground ...
Robert L. Day, Caijun Shi
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Durability of concretes containing natural pozzolan

Proceedings of the Institution of Civil Engineers - Construction Materials, 2008
In this study, the effects of tuff natural pozzolan on properties of Portland cement were investigated. The durability and mechanical properties of concrete made by these cements were studied. It was found that using the natural pozzolan does not significantly affect the mechanical properties of the Portland cement.
M. Najimi, M. Jamshidi, A. Pourkhorshidi
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Importance of using the natural pozzolans on concrete durability

Cement and Concrete Research, 2002
Abstract Natural pozzolans have become important because of their role in concrete durability. This situation has provoked an increase in the use of pozzolanic cement in concrete construction. This paper reports results of different portland–pozzolan cements containing different natural pozzolans, and they were compared with ASTM Types I, II and V ...
R.E Rodrı́guez-Camacho, R Uribe-Afif
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Effect of Calcination on Natural Pozzolans

1950
Calcination will improve the quality of some pozzolans, reduce the quality of others, and induce pozzolanic properties in some otherwise essentially non-reactive-substances. Natural pozzolans or natural materials in which pozzolanic properties can be induced by calcination at temperatures less than 2000 F.
RC Mielenz, LP Witte, OJ Glantz
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Development of Blended Pozzolans Using Natural Pozzolan and Ground Glass Through Reactivity and Durability Investigations

Advances in Civil Engineering Materials, 2022
Abstract This study emphasizes the reactivity evaluation of pozzolans and the durability performance of blended cements containing pozzolans. A ground glass, three raw natural pozzolans, and two blended pozzolans of ground glass and raw natural pozzolan were examined for reactivity using the modified lime-reactivity test, the strength ...
Mahipal Kasaniya, Michael D. A. Thomas
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Production and Use of Calcined Natural Pozzolans in Concrete

Cement, Concrete, and Aggregates, 2001
Abstract The goal of producing concrete that provides longterm durability with regard to properties such as improved sulfate resistance and reduced susceptibility to alkali-silica reactions (ASR) has led to the development of several high-performance materials.
GS Barger, ER Hansen, MR Wood, T Neary, DJ Beech, D Jaquier   +5 more
openaire   +1 more source