Document Type : Original Article
Authors
Civil Engineering Department, Faculty of Engineering, Sinai University, Arish City, Egypt
Abstract
Recently, the production of electrically conductive concrete (ECC) has become
widespread by using carbon materials such as graphite powder GP. To eliminate
the negative impact of using graphite powder (GP) alone as an additive to concrete,
one of the supplementary cementitious materials (SCMs), such as silica fume SF,
is combined with graphite powder (GP). In this respect, research work was
conducted on concrete mixes with a cement replacement with silica fume with an
SF ratio of 10% and with cement replacement levels with graphite powder (GP)
ratio of 2.5, 5 and 7.5%. A control concrete mix (MCC) was made with 100%
cement with no supplementary cementitious or carbon materials. Concrete mixes
were tested in rheological properties such as slump and in hardened properties such
as compression, indirect tension and flexural. Concrete samples were tested in
compression at the ages of 3, 7, 28 and 90 days and were tested in indirect tension
and flexural at the ages of 7 and 28 days. The durability of the concrete samples
was examined in both the rapid chloride penetrability (RCP) test and the scanning
electron microscopy (SEM) test. The compressive strengths of concrete mixes,
MSF-GP2.5, MSF-GP5 and MSF-GP7.5 increase by about 11, -0.3 and -7%
compared to MCC but were reduced by about 7, 18 and 21% when compared to
MSF, respectively at the age of 28 days. Tensile strengths of concrete mixes, MSF-
GP2.5, MSF-GP5 and MSF-GP7.5 were increased by about 19, 3 and -10%
compared to MCC but, were reduced by about 7, 20 and 29% compared to MSF,
respectively, at the age of 28 days. Flexural strengths of concrete mixes MSF-
GP2.5, MSF-GP5 and MSF-GP7.5 increase by about 12, -0.3 and -6% when
compared to MCC but were reduced by about 7, 17 and 21% when compared to
MSF, respectively, at the age of 28 days. Inclusion of graphite powder in silica
fume concrete increases the rapid chloride penetration (RCP) and reduces the
pozzolanic effect of silica fume on cement matrix.
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