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This study introduces a novel geotechnical composite material comprising two types of fill material sourced from the paper industry—deinking paper sludge ash (DPSA) and deinking paper sludge (DPS). Five composites with different DPSA and DPS contents were investigated. Two composites were selected for further analyses. The technology and procedure for composite installation were implemented in field tests. The composites with 80% and 70% DPSA exhibited the elasticity required to withstand minor landslide slip deformations, in addition to achieving sufficiently high values of uniaxial compressive strength. The composites had a low maximum dry density value, which led to fewer settlements in the entire support structure. The enhanced shear characteristics can enable the construction of a thinner retaining wall. The delay between preparation and installation of the composites was further investigated. The field tests confirmed that the composites with 80% and 70% DPSA can be installed on the construction site 4 h and even 24 h after mixing. In 2018, a retaining wall structure with 70% DPSA and 30% DPS was successfully implemented near a railway line using conventional technology as followed-up research to the herein presented study. Results have been derived from work performed in the scope of the H2020 Paperchain project in which novel circular economy models centered on the valorization of the waste streams generated by the pulp and paper industry as secondary raw material for several resource-intensive sectors, including the construction sector, have been developed. Environmental benefits are savings in natural raw materials, reduction of landfill disposal as well as CO2 emission reduction. [ABSTRACT FROM AUTHOR]

Abstract: Permeability is one of the fundamental properties of concrete structures as it is strictly related to durability. Mitigation of the degradation processes induced by aggressive solutions can be achieved by controlling water penetration through the pore network. In this study, we test the potential use of nanocomposites as waterproofing agents in concrete. Macroscopic measurements show that the addition of a small amount of nanoparticles effectively reduces the extent of the water permeation front. A combination of experiments, based on X‐ray tomography, mercury intrusion porosimetry, and BET nitrogen adsorption, and of numerical simulations, are used to interpret the macroscopic observations. These investigations show that C–S–H precipitation away from cement surfaces, induced by the presence of nanoparticles, leads to a refinement of the pore network. Such a microstructural change in the cement matrix results in a net reduction in the overall concrete permeability. [ABSTRACT FROM AUTHOR]

Detailed characterization of calcium aluminate rich secondary steel slag derived from two different refining processes of stainless steel production has been performed in order to gain generic knowledge about this by-product, and its behaviour as a supplementary cementitious material. Additionally, slag blended cement composites were investigated and compared to a limestone filler blended cement composites and to a reference cement composites. The results showed that the investigated slag contained several hydraulic phases, mainly in the form of calcium aluminates. In the case of the slag cement composites, a larger proportion of hydration products was observed than in the case of the limestone cement composites, as well as a higher rate of strength increase. [ABSTRACT FROM AUTHOR]