سال انتشار: ۱۳۸۷

محل انتشار: همایش بین المللی ژئولیت ایران

تعداد صفحات: ۹

نویسنده(ها):

Abdullah Keyvani – Engineering Faculty, Azarbaijan University of Tarbiat Moallem, Tabriz, Iran
Ramin Nasrollahpor – Engineering Faculty, Azarbaijan University of Tarbiat Moallem, Tabriz, Iran

چکیده:

Natural zeolite can be utilized not only as a pozzolan but also as a microfiller in the concrete for the
overall densification of microstructure. The pozzolanic reaction of zeolite showed reduction in calcium
hydroxide component of portland cement hydration in the neat zeolite-blended cement pastes are measured
at varying levels of zeolite additions. Results show a clear decrease in calcium hydroxide contents in zeolitecement
pastes and greater reduction of calcium hydroxide in pastes having higher amounts of zeolite
incorporations, indicating a higher degree of pozzolanic reaction. Incorporation of zeolite causes the
following important microstructural modifications, which are responsible for the overall improved durability
of concrete: (a) a decrease in calcium hydroxide component of portland cement hydration in the paste by the
pozzolanic reaction, (b) densification of the cement paste microstructure by combined pore-size and grainsize
refinements, which cause an increased volume of very fine pores at the expense of the large pores, and
(c) improvement of aggregate-paste interfacial zone by a combination of filler effects and pozzolanic
reaction effects. Zeolite incorporation showed a significant reduction in the potential for Alkali-Silica
Reaction (ASR) expansion in our test where the paste contained highly reactive borosilicate glass as
aggregates. It is indeed this alkali-binding capacity of the zeolite-cement paste along with the overall
densification of microstructure, which have contributed to this reduction in alkali aggregate expansions.