Based on the investigation reported in this study, the following
conclusions can be drawn:
1. The initial setting time and the final setting time of cement
pastes are not so much influenced by the use of marble dust.
2. Expansion measurements of cement paste show that the
expansion value is not considerably affected by the use of
marble dust, where this value ranges from 2.00 mm to
2.75 mm.
3. TGA test results indicate that there is no change in phase
chemistry for cement paste modified with marble dust compared
with control cement paste and the variation of calcium
hydroxide content is insignificant.
4. SEM investigation shows that the morphology of the internal
structure of paste specimens with and without marble dust
are not considerably different from each other which verify
that marble dust has no noticeable role during the hydration
process.
5. The compressive strength of cement mortar increases by the
use of marble dust as cement replacement
6. A reduction in the compressive strength of marble
dust modified mortar of 5.0% lower than control
specimen is reported at 15.0% marble dust as cement
replacement.
7. The compressive strength of concrete made with 15.0% marble
dust as cement has been found to be either comparable
or less than control mix.
8. The concrete compressive strength increases with the
increase of marble dust ratio as sand replacement up to
15.0% of sand by weight. Also, The use of marble dust as sand
replacement is more effective with lower w/c ratio.
9. A significant improvement in concrete tensile strength is
recorded due to the use of marble dust as cement replacement
as well as sand replacement.
10. The use of marble dust up to 15.0% as cement replacement
or as sand replacement positively affects the steel-concrete
bond strength.
11. The maximum improvement in steel-concrete bond strength
is recorded with 10.0% marble dust as a replacement for
cement or as a replacement for sand.
12. The use of marble dust up to 15.0% by weight as a replacement
for cement or as a replacement for sand has insignificant
effect on the ultrasonic pulse velocity test values.
13. The use of marble dust in concrete as cement replacement or
as sand replacement can produce less porous concrete compared
with concrete without marble dust.
14. In general, the use of marble dust as sand replacement has
more significant effect on the mechanical properties of concrete
compared with using it as cement replacement.