Industrial Waste Aggregates - Recycled Aggregate in Concrete - page 52

Fig. 2.8 Sieve analysis of
mine wastes (Yellishetty
et al. 2008 )
that the used sludge is coarser than the sea sand. About 50 % of the particles of
sludge are coarser than 2 mm compared with sea sand in which 100 % of the
particles pass the 2.36 mm sieve. The chemical analysis of the waste shows that it
has a low pH value with acceptable levels of other chemical parameters and falls
within the permissible limits established in Bahrain for use of waste in construction.
Kuo et al. ( 2007 ) reported the use of petroleum reservoir sludge as fine
aggregate in the preparation of cement mortar. The composition of sludge is
presented in Table 2.20 . The sludge contains very high amount of smectite clay
([60 %), which can cause a detrimental expansion to some extent, when it is
mixed with water. Hence, reservoir sludge cannot be directly used as fine aggre-
gates in concrete and therefore, before using it as aggregate, hydrophilic sludge is
converted into hydrophobic by using a cationic surfactant.
The sieve analysis of modified sludge organically modified reservoir sludge
(OMRS) along with normal sand is presented in Table 2.21 . More than 80 % of
the OMRS particles are smaller than 0.6 mm but larger than 0.075 mm. From the
thermal analysis of reservoir sludge before and after the treatment, the authors
confirmed that the OMRS particles have been organically modified and became
hydrophobic before they were mixed with water, quartz sands and cement.
Kinuthia et al. ( 2009 ) reported the use of dark coloured colliery spoil, generated
during mining of coal as replacement of fine and coarse aggregate in the prepa-
ration of medium strength concrete. It was obtained as two materials, a fine
fraction of low plasticity, and a coarser non-plastic fraction. The two fractions
were blended in equal proportions to produce a well-graded colliery spoil material,
which is presented in Fig. 2.9 along with other constituents of prepared concrete.
The specific gravity of both types of spoils was 1.8 and lighter than normal
aggregate.
Ilangovana et al. ( 2008 ) reported the use of quarry rock dust as fine aggregate in
the preparation of concrete. The authors defined the quarry rock dust as residue,
tailing or other non-valuable waste material after the extraction and processing of
rocks to form fine particles less than 4.75 mm. The level of utilisation of this dust in
nations like Australia, France, Germany and UK has reached more than 60 % of its
total production. The physical properties of the used dust are presented in Table 2.22 .