| dc.description.abstract | Recently, 3D concrete printing (3DCP) has been gaining prominence in the construction
industry. However, in order to meet the extrusion requirements, 3DCP mixtures are usually
dosed with high Portland cement contents. Thus, a solution seen as promising to make this
technology more sustainable is the reduction of cement consumption through partial
replacement by mineral additions. In view of this, the present research aims to develop
composites for 3D printing containing different percentages of limestone filer and metakaolin
as binder fraction of the analysis compositions. The proposed mixtures encompass
replacement contents in 30% limestone filer, 40% limestone filer, and 30% limestone filer
with 10% metakaolin. In the fresh state, these composites were evaluated through the tests of
spreading, slump, bulk density, incorporated air content, squeeze-flow and buildability. In the
hardened state, flexural strength, compressive strength, interlayer adhesion, specific mass,
void index, and water absorption by immersion were analyzed. In general, the mixtures
demonstrated compliance with the requirements of the printer handled. A highlight is given to
the composite containing 30% filer with 10% metakaolin that, with the ideal amount of water,
evidenced good print quality and excellent buildability of the printed part. The mixes
containing only filer showed higher deformability of the mixture, and this characteristic is
directly proportional to the content of incorporation of this material. The behavior in the
hardened state, in turn, indicated that it was related to cement consumption. The higher this
parameter, the better was the mechanical performance. In relation to the reference mixture,
the mixes containing 30% filer, 40% filer, and 30% filer with 10% metakaolin showed
behaviors of, respectively, -24,5%, -34,4% and -31,4% (flexural strength), -43,8%, -50,2%
and -36,5% (compressive strength) and -2,2%, -19,5% and +0,5% (interlayer adhesion
strength) at 7 days of age. Moreover, the content of void index and water absorption by
immersion were higher as the value of specific mass of these composites was lower. It is
possible to conclude, therefore, that there is the possibility of obtaining printable mixtures
with reduced cement consumption and that are in compliance with requirements necessary for
the printing system used. | |
