Avaliação de um solo arenoso-siltoso estabilizado com cimento Portland e adições minerais para uso em manufatura aditiva para a construção civil

Abstract

The aim of this work is to analyse a soil classified as sandy-silt and check whether it is compatible with the 3D printing process, stabilizing it with Portland cement using chemical additives to provide the pumpability required for printing, partially replacing the cement with mineral additions (metakaolin and limestone filler), so that the soil-cement mixture has a paste volume suitable for the 3D printing system. The experimental program began with an empirical analysis of the mixtures, starting from the soil:cement mixture with a mass ratio of 1:1, called the reference (REFT100), in order to obtain a mixture with a consistency compatible with the extrusion method of the 3D printer available at UFRN, in order to establish the chemical additive contents and the water/dry materials ratio compatible with the conditions of speed and height of the printing nozzle. From this mixture, the reduction in cement consumption was analyzed in two mixtures called T15%C and T20%C with mass proportions of 0.15:0.85:1 and 0.2:0.80:1 (cement:mineral additions:soil). The number of possible layers for printing 3D blocks to be built continuously and without crumbling was then determined using a constant printing speed of 80 mm/second with a deposition height of 1 cm. With these printing conditions established, 6 soil-cement blocks were printed, of each composition, with dimensions of 14 cm x 19 cm in cross-section and 16 cm in height, where 3 blocks were subjected to dimensional analysis and then the axial compressive strength was determined, and 3 blocks were used to extract samples of (40x40x160 mm) to carry out compressive strength and flexural tensile strength tests. With the mixtures analyzed, it was possible to build soil-cement blocks with cement consumption of 113.60 kg/m³ and 152.78 kg/m³, in the T15%C and T20%C compositions, respectively, which represents a cement reduction of 87% and 82%, respectively, compared to the reference mixture (REFT100), which used only cement and soil. The block using the reference mix (REFT100) had the highest compressive strength (19.8 MPa), while the T15%C and T20%C mixes had strengths of 3.1 MPa and 3.0 MPa, respectively.