Hydration and rheology control of concrete for digital fabrication: Potential admixtures and cement chemistry

Effect of viscosity modifier admixture on Portland cement paste hydration and microstructure

“…approached the need to control rheological properties of fresh cementitious mixtures to be applied for 3D printing. In that article several different types of admixtures are discussed and the importance of VMAs for the pumping, extrusion and deposition phase of printed cement-based composites is acknowledged [19]. Thus, the use of VMAs in the construction industry helps concrete technologists to keep viscosity and yield stresses of mixtures under control.…”

Shifting factor—A new paradigm for studying the rheology of cementitious suspensions

“…The illustration shows that the black and the blue lines do not have any common experimentally accessible volume fraction. In other words, without the approach presented in this paper, it would be impossible to determine the interparticle force ratio from Equation (5). because yield stress values could not be measured at the same volume fraction.…”

“…Experimentally, we obtain a first data set using Equation (7) and taking the ratio between the exponential prefactor of the reference paste, a Ref , and that of any series i, a i . A second data set is obtained using Equation (5) and taking the ratio between the yield stress of a reference paste and that of a dispersed paste. In these cases and for the high volume fractions used, the reference paste was too cohesive to be measured so that its yield stress was calculated by using Equation (10).…”

“…Additional benefits obtained from using PCEs include a reduction in the environmental footprint of concrete (for example, by enabling a reduction of the clinker content in concrete), as well as an extension of the service life (by allowing the production of denser concretes) . Moreover, superplasticizers are extensively used in numerous high added value applications, such as Self‐Compacting Concrete (SCC), Ultra‐High‐Performance Fibers Reinforced Concrete (UHPFRC) and digital fabrication …”

“…3,4 Moreover, superplasticizers are extensively used in numerous high added value applications, such as Self-Compacting Concrete (SCC), Ultra-High-Performance Fibers Reinforced Concrete (UHPFRC) and digital fabrication. 5 As a result, the topic of rheology control has received much attention over the past years, 6 covering theoretical understanding of flow tests, 7-9 thixotropy, [10][11][12] working mechanisms of concrete admixtures, 2,13 as well as bleeding and/ or segregation issues. 14,15 Moreover, important progress has been made in understanding how, in relation to their molecular structure these admixtures can slow down cement hydration, a side-effect that is most often undesired.…”