Assessment of the Pozzolanic Reaction of Crystalline and Amorphous Rice Husk-Ashes

Title: Assessment of the Pozzolanic Reaction of Crystalline and Amorphous Rice Husk-Ashes
Author(s): da Silva Rêgo
Paper category : conference
Book title: International RILEM Conference on the Use of Recycled Materials in Building and Structures
Editor(s): E. Vázquez, Ch. F. Hendriks and G.M.T. Janssen
Print-ISBN: 2-912143-52-7
e-ISBN: 2912143756
Publisher: RILEM Publications SARL
Publication year: 2004
Pages: 715 - 724
Total Pages: 10
Nb references: 13
Language: English

Abstract: The incorporation of industrial residue to cement as mineral admixtures is one of the solutions
for making use of byproducts from other industrial sectors in nobler purposes such as the
partial substitution in cement, thus enriching the properties of the final product, in addition to
disposing of the residue adequately. Rice husk-ash (RHA) is one of the mineral admixtures
that has been relatively well studied in recent years, although it has not been commercially
used by the civil engineering industry. Depending on how the husk is burnt, RHA can be
classified in two groups: (1) Crystalline RHA - produced without control over the burning
process; and (2) Amorphous RHA - produced with controlled burning. The basic difference
between crystalline RHA and amorphous RHA is the content of amorphous material found in
the ashes. According to several authors, the greater the content of amorphous material, the
greater the reactivity of the RHA. Another important factor in RHA reactivity is to what
degree it has been ground. In terms of physical characteristics, those of greater importance are
related to fineness, in all its manifestations and expressions, since different grading fractions
behave differently. The aim of this paper is to investigate the influence of the index of
amorphousness and the degree of fineness on the pozzolanic activity of RHAs, thus
contributing to a better understanding of the pozzolanic reaction under study. By using major
tests to evaluate pozzolanic activity, the significant influence of the degree of fineness on
RHA pozzolanic activity was verified. The index of amorphousness seems to have smaller
influence as can be verified by the high reactivity of crystalline RHA when it is finely ground.

Online publication: 2004-09-29
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2912143756.079