Title:
Use of Condensed Silica Fume as Filler in Blended Cements
Author(s):
M. Regourd, B. Mortureux,
and H. Hornain
Publication:
Symposium Paper
Volume:
79
Issue:
Appears on pages(s):
847-866
Keywords:
blended cements; bond (paste to aggregate); compressive
strength; C-S-H; electron microscopes; fly ash; microstructure;
mortars (material); pozzolans; silica; slags.
DOI:
10.14359/6729
Date:
5/1/1983
Abstract:
At early ages, blended cement mortars with 30 % hydraulic slags or active pozzolans have lower mechanical strengths than mortars incorporating 100 % Portland cement. The action of 5 % condensed silica fume replacement for slag or pozzolan or material considered as inert has been studied from 7 days to 3 months by measuring the mechanical strengths of mortars made according to IS0 test method and by observing the microstructure of fractured samples. This action of the condensed silica fume is a function of the nature of the additive. With hydraulic slags, there is a competition between slag and silica fume for the available lime. With slightly or slowly reactive pozzolans (volcanic rock, fly ash) mechanical strengths and microporosity of mortars show improve-ment at 28 days. With inert materials (crystalline slag or quartz), the improvement is more marked. This is due to the formation of dense C-S-H, strong cement paste-aggregate bond and 20 % increase in mechanical strengths.