Abstract:
Laboratório Nacional de Engenharia Civil (National Laboratory for Civil Engineering), in partnership
with Faculdade de Ciencias e Tecnologia da Universidade Nova de Lisboa (Faculty of Sciences and
Technology, NOVA University of Lisbon), have studied the technical feasibility of applying two recycled
aggregates, one processed from electrical arc furnace steel slag and the other from concrete of
construction and demolition waste (CDW), in the construction of the leachate collection and removal
layer (LCRL) of municipal solid waste (MSW) landfills. In the paper is presented and discussed the
hydraulic behaviour of these materials based on results obtained in permeability tests carried out on
specimens prepared from grain-size in the ranges 0.25-2.0mm and 2.0-20.0mm, given that, in
Portugal, the LCRL is composed by an upper layer of 0.2m thickness constructed with particles in the
range of sand and a lower layer of 0.3m thickness constructed with particles in the range of fine
gravel. Aiming to test their hydraulic behaviour to more aggressive conditions than those observed in
MSW landfills, the leachate used in permeability tests, which was collected at a Portuguese MSW
landfill, was acidified with hydrochloric acid to decrease the initial pH from 8.2 to 5.5. As a reference
for the results obtained with the recycled materials in contact with the leachate, the same permeability
tests were performed with tap water. In general, the hydraulic conductivity of tested materials was
higher than the minimum (1x10-4m/s) required by Portuguese decree-law in force. Therefore, the
results obtained suggest the possibility of applying both recycled aggregates in the construction of the
LCRL of landfills.
