Study of Portland cement mortar with textile sludge
Marcos Antônio da Silva Júnior, Ester Oliveira dos Santos , Flávio Eduardo Gomes Diniz,
Ana Cecília Vieira da Nóbrega, Sávia Gavazza dos Santos Pessoa, Érika Pinto Marinho*
Universidade Federal de Pernambuco. Centro Acadêmico do Agreste. Núcleo de Tecnologia.
BR 104, Km 59, Nova Caruaru, PE. CEP 55014-170. Tel/FAX: (81) 2126-7772
Portland cement composites are promising materials to stabilize potentially toxic substances,
since the reactions that occur during its hydration allows the incorporation of metals and
organic compounds. The objective of this work was to investigate a viable alternative for the
final disposal of textile sludge from treatment plants of jeans industry by using it as an
additive on Portland cement mortar. The textile sludge studied is produced in treatment plants
of jeans industry located in Pernambuco (Northeastern Brazil), and its composition is rich in
metals and dyes. For this purpose, mixtures of sludge-cement–sand-water and sludge-cement–
lime-sand-water were prepared and stabilized/solidified. The mortar were placed in
cylindrical molds and cured in water. The specimens were tested in order to determine their
setting time and compressive strength after 28 days, and then analyzed by XRD, SEM and
FTIR. The characterization of the sludge showed that it has a slightly acid pH, high humidity
and some metals. Aluminum (~54000 mg/L), Calcium (~4500 mg/L) and iron (6300 mg/L)
are the metals most abundant in this textile sludge. The results showed that the sludge affected
more mortars without lime. Probably because the presence of lime corrected the pH disturbed
by the addition of textile sludge, making it more favorable to hydration reactions that occur at
high pH. The textile sludge does not affect the setting time and fluidity of the mortar. The
compressive strength was not affected in sludge-cement–lime-sand-water composite.
However, the compressive strength of the sludge-cement–sand-water composite is diminished
to 50%. The evolution of mechanical performance is interrupted at 7 days curing. XRD
patterns show that calcite phase is formed in sludge-cement–lime-sand-water composite. It
was not observed in sludge-cement–sand-water composite, suggesting that lime reacts to form
calcium carbonate. SEM images show a porous microstructure and formation of the
deleterious phases, as ettringite. Leaching tests suggest that metals are not solubilized,
indicating that the composite stabilized the textile sludge. These results suggest that the
addition of textile sludge in Portland cement composite can be carried only at low
concentration, rather in mixtures containing lime.
Keywords: Portland cement, textile sludge, SEM, compressive strength.
Work supported by: CNPq, FACEPE.
[1] Hewlett, P. Lea's Chemistry of Cement and Concrete. 4th edition. Elsevier. 1998.
[2]Taylor, H. F.W. Cement Chemistry. 2nd edition. Academic Press. 1997.
[3] Malliou, O.; et. al. Cement and Concrete Composites, 29 (2007) 55-61.
* Correspoding author: [email protected]